class rather than the pale class. Because of the very sharp expression of variegation among the Spm carrying kernels and also because of the faint 5718 _ pigment produced in its absence, this/state of a has been useful in a 1 number of studies of the Spm system. : . m-1 Subsequent tests conducted with plants having state 5718 ay and Spm have indicated that the appearance of kmenels having the Ay phenotype in its progeny is rare, The number with this phenotype derived from tests of plant 60l.6B-l entered in table 15, is unusually high. In-this-—eeses, 40 Fhe Same collection of pollen was used te=makeebetb-tee self-pollination and tov the test cross entered in this table, tt is suspectcd that the tassel of mutant A this plant Bedm which pollen was collected had a small/sector } and Cormud WP Ay amukqud aut that the pollen grains mmzexrimg derived from anthers in this sector Were vuanetirr Sryicdy resnonsible for the appearance of the pete ewes number of ke nels exhibiting the A, phenotype, kernels gexrivesx A number of plants were grown from/@ne esrs produced by crosses conducted with slant 5720. With rare exceptions, the state of at in Zbois lant exxried and in its progeny gives rise in plant and kernel to mutant areas thet exhibit only low levels of pigment intensity. As mutation inducting events may occur very early in development of efftimr clant tresses ‘WG : ged“ sporogenous cells sme in metephy tion » a number of 7? carry m-1 gametes are formed by plants having this state that haywz a mutant of ay The»efore, many kernels appear on test cross cars thet expross this. 3 J = £ One grade of pigment intensity is expressed in e°wth but the range of this ( plukeo - -) among the mutant carrying kernels is from very faint to meditm d«rk, A m= When a plant having this state 5720 of ay and also Spm is used as a pollen parent in the cross to plants homozygous for ays only one of the three chromosomes 3 in the endosperms of kernels on the resulting ear carries : Mie : . a +4 a . ; this ay 1, Among the variegated class of kernels with this constitution, mutant ares appear. Each expresses one particular erage of pigment intensity within it. when, however, the reciprocal cross is made, among ava iyo of aah the variegated keznels on the resulting ear, mutant arecs wey appear within A “A wom wateh therc are smaller areas exhibiting deeper shedes of pigment intensity. yA va stole S1to on bata ar M1 2 : This is expected these Korte 1s heste=bite-stao—of a. 1 in two of its A c. ave three chromosomes 3 and Inutation-inducing events macur to each inderendently Ay Would owe rune To We 0 4 nore ated 2iprseiow | of ome-anotner. Types of kernels appenring one ears vreduced fmom crosses A of seme plants that were at (state 5720 )/a, to plants homozygous for 1 are given in table 16, In this table it will be s-en that the number of ‘ Y 10 uniformly pigment d k= nels acs high as wedsdeees the number of cotarless Qurovy Tho AAU foweds Pa ceroutcef Oboe rd Potuso, wr one $k wens Upper’ grocer cd. Peal, kernels, It was subsequently learned that with state S720, no anthocranw A * ations wee Myiacukal Lads Rowed eames dhe bard eter Greet? tye, 78 a cS pigment is produced in either plant oy kernel when Spm is absent. Ferm Rw The high whe paar apn reserbled that produced by the o cast . . a . Mal rate of germinal mutation vroduced bx this 5720 state of a ide y 1 vriginal state of ay from which it was ~ derived, Howev.r, with this original state, the majority of germinal Muokaurty tut AA pr Lach Lops Pi queuat wleanily amenbluny or g& mutations give rise to, tae full—oxr Heer Bett —A—tspe—onpression, The of germinal musesiens LUT prvedued ypc proportion/thet express leseme levels of pigment intensity DI considenably Lensy, regent onwunbluny By wlan och t-—— Because of the very high rate of geminal mutation given by the original A m= dua ak0% 1 » #t wos not considered State of a to se a useful one for analysis of the mode of oporatiocn of the Spm system and tests of it wers not continued ) Ww beyond the 19B1 season. QU eo ae E ak wy 5720, utuch vo miles’ Ss Oucue ataly “4 ys wa lwo 4 CRembnp 4 Ati Puy (von qul Was sud . 79 5. Individuality of expression of each state of at when two different ones are youre in a plant or kernel. During the summer of 1951, crosses were made between plants m1 Ahota ly carrying different states of By and the type of expression of each Curren“ yper Ula 0 stave im the kernels on the resulting ear was examined, Pre €ombinatiers oak Weta Guy togethers vA Q Runge howl Vay fotlocoue af tlhe oa me! state 5719A-1 with state 572C and with the original state, state 5718 with the original state, state 5720 with. the original state, and state 5719A=2 with state 5700A, not previously discussed, orn Dain. yore, Yr. eerabonclian 2 SteThn were om ade, Welbon. , v0 achauh wip) -tilfeie The most instructive cross gr thes. illustrated the i dividuality of ae ped when Cowal a o- ROv0 or Dew state of a)", was that, between” plant} carrying stete 5719A-1 6) ents . amnade “4 Quan. carrying state 5720 ,and fhe types of kernels avpearing on tee ear produced by one such cross will be given. Pollen from slant hOl2-9, thet carried state 5720, was ~laced on the silks of a tiller ear of vlant 60).6C=1 Qn ouseito ake Oar vies wrubly ob rau {uma Dy 0u>, ur lu Le rusongau, Tp Sod ttn Unt exate which marxrkedxskxkexs¢tGAxukxx was aa hotiozveous for state O71 A 1.’., The “a of the main stalk of plant 60l.6C-1 was self-~pollineted and on th bob resulting ear there were 4 uniformly pigmented kernels exhibiting ‘timex Are por oxcqaunilea busy Da wibtnnily 4 Was prs bape, quik wan oy OCUnE ua cof) 2m type pigment, 31 that weve unifarmly’ ¢ ’ sx 377" Bhat had small A OM odetins Whore wie spots of the A, type pigment in a colorless background,-- the typical ond \ owe That append Tbe lalty tefatun, pattern produced by state S57LOA-1. » Pollen of this plant was aksa placed Sur purr vou 66 - wor rip rena, | Ms ompeedion abalone Med seco (Cid first ear es earg at lpayo boa 80 212 kernels thet were uniformly pale colored, and 465 that expressed the variegation pattern typically produced by state srigk-1. Uf Prent 602-9 variegated had been derived from a/kernel on the self-pollinated ar of plant 5720. Pollen from a plant homozygous for a, had been placed on the silks of wy 1 ow tun - . ~¥ . fla tiller eat of this plant. The kernel tynes that aepouned . en t+he-—resulting ear were as follows: 32 uniformly pigmented kernels, each ebay Spar ticular prequels but in level of intensity eo NY on/all of thémithis level was low, 102 variegated kernels with betk la» Be, and small areas exhibiting low levels of and pigmenteintensity/in a colorless background, andQn addition, 239 kernels in which no pigment was observed, When vollen of plant 6042=9, with On 20r. of a Wher state 5720, was »laced on silks of atétter-ear of plant 606-1, “at wes Th On will We Dr owurt olody learned that the vrollen parent was homozygous for state 5720¢ Thus, the cposs was made between a plant homozygous for state 5719A-1 and one homozygous for state 5720, There were 216 kernels on the ear this cross produced, Four of them were uniforly pale colored, In 18 others, spots awing A,- type pigment were present in a webferniy lightly pigmented backerous . ok ow Che pattern of the A, spots was that characteristically produced by state 5719A-1. The intensity of the background pigment was uniform over the VA aleurone layer fer each kernel but the level of this differed among there Dig Vaunge dy kernels, And, these levels w@me the same as Seer that ase pxantuxeax “A i yA crn Ye Cua ivi of & make trwile Carle & cncbaay cbbrtat fears 10 9:7 20, 81 appecring among the uniformly pigmented kernels on ears produced by the cross of plants having state 5720 to plants homozygous for Ay. In addition, Or Cucror th there were 19. variegated kernels, These kernels had the pattern of A 1 spots produced by state 5719A-1 and also the pattern of lightly pigmented areas characteristically produced by state 5720 1 vamp gcition 24 Luba by theo Rermte- pattern was that which could—be—expeeted from superposition of the A Werle Qap patétern produced by one state over that produced by the other, Each Won ar state expressel its own tyne of response to the presence of Spm. A . (see photos), The over-all It was assumed that in the 18 kernels ssowing the variegation pattern ADV Led pcx coteler® Ov» Lipp} eee produced by state 5719A-1 tn a uniformly pigmented background, a—zkxbhe aua that these matent,;stable in the presence of Spm, hed-—been- contributed by-the- parent avd Out Wao: fondn carrying stete- 5720, The correctness of this interpretati n was made evident in tests of the plants derived from kernels of this type that were s : . conducted in @ subsequent years The plant derived from each carried a m-*, , . of a, in one chromosome 3, ti mutatit/whose exoression was stable either in the presence or the absence of Spm, and the state 5719A~1 of a," in the homologue which e ntinued to Roany express its individual variegati n pattern in subsequent generations, - - “4 . Ld Cranrery A description of the types of test that established this will be postponed until a description may be given of the means by which such tests ave M poser bie. Qu enuf avat , Wow plants Viruncg fore au ant Chane! Vere abet | (eater 7 lp alley . ; ¢, 5 a ond Clrerpuud 2 Creed POG 57/7A-1 a te Lip eg So Ub gT up a4 {lat te Luaup Litin BHORO iy. due ding 3? 62 As described earlicr (page. ), plant 5700A was derived from a very pale colored kernel on an ear produced by cross of the original ae Carrying plant to one that was homozygous for a Pollen of »lant 5700A 1° was placed on silks of an esr of a plant homozygous for Aye Iwo ty es of kernels appesred on this ear, those that were very pale in color and those thst were colorless, An accurate classification of the two types was not attempted as the intensity of pigment in the pale class was so belonging _ktul tbe det oek-af) aul outa low that it was feared that some/in the class would | be placed with" the colorless class, Some kernels that certainly had pigment in thém were selected from this car, and the vlants gpown from them in the a mmer of 1951 wore given culture number 6078, At least one esr of each plant in this culture received pollen from a -lant homezygous for ay and shy. On all very, ears so produced, there wire only the two classes of kernels$/pale colored ron tt Swe hom AT pe for ath hbwuto OAL and colorless, Hocurate classifientiend wase also difficult to 2 Oa silks of a make 6h some of these ears, As an example,/the first ear on the main oehe = = stalk of plant 6078-5 received pollen from a plant homozygous for ay and = ~ a CPOU XN BE > sh On the resulting ear, 256 kernels certainly had pigment in them , = i 7S YW wera - promt eouead pot Le eto at by Venue Sa tucealiin, 3 3 but the remaining 31) anocared to be colestess, A tiller ear of t >is “A plent was self-pollinated and simklar difficulties were encountered in making “hat op prud on of accurate classifications of thegtwp classes of kernels. Among the lal. ur wal 83 this ear produced, 25. had faint pigment in them but the remai ing 170 appeared to be colorless. The silks of an ear on another tiller of tet. bo1%-> whose constitution wes, 4 plant received pollen from vlant 6080-7) stricaix was @4 “ 4 . . i, an ws towit ulin. |e Ao ad Vy pos OD earns On Cer cpr Wie AUnprerwe, Befae drdide t (Bbu_decrintion of iets siete,sée paces..——} , The first ear on the Died, A ured be mictvrcers to Conriete the emotion A Wout 08 0C-7.) gy) main stalk of vlant 6080C-7 nae $8 on self-pollinated and among the 23), oul Chr kernels It-predueed, one was fully A, in vhenot:me, none were pale, 172 were varicgated for dots of Ay in a colorless background, and 61 were colorless. The second ear on the main stalk received pollen from a plant honeczygous for Ay On the ear this cross produced there were 11 pale Cakole sNQR-+ mn cole pau) colored kernels, 97 showing dots of A, in a colorless background, and 127 that were colorless. ({Porien cOllect-:-d from a tiller of thete plant Go%0l-7 ot Oo was placed on the silks of an ear puedvecd—bi—a secome tiller of plant So Wrens quit Auk po 5 -T wee hs mod abree, On motion en, 6078-5. fhe types of kernels appearing on thi@® ear were surprising. 4 { prodiead 4, Uno Colliy exer There were 2 kernels exhibiting the full Aj~ tyre pigmentation, 75 kernels that were uniformly pale colored, and 132 that anneared to be colorless, In gddition, there were 259 variegated kernels, Hichty-three of them had -ebyd wR | dots of A, in a colorless background--the pattern of variegation associated A 1 Q very, dowre palin A Ar bod an wilt dr cowe Langu. with state 5719A-2, The remaining 176 variegated kornels evhibited = wu wn GUA few-teweee areas ef full Aj-tyve plement and— Tet 3 8h. kernels there wero a few hy ain areas and in otrer a fow areas | that appeared Wy ‘ohereetou yao, td (roduedon udp Ane g” . to be colorless, Lt was susvécted immediately that the plants in culture WD Dhow Spun, Wun ater] CUNEO Mrbley Fe cued Om the eyasy pokeeasup' 6078 had a modified state of ay but no Spme , Introduction of Spm through a male gamete of plant 6080C-7 revealed the pattern of variegetion this state would produce in its presence, CH sunsoouont tests substantiated Actin drow fe Gade § bso Yala 44.) jnteeut ws plow 9 Barblicy GETS, ep aa pawl, b 700), this, They commenced with plants derived from the pale class of ke:nels the on ears of tkesplants in culture 6078 that were produced by cross J| with plants homozygous for a, and sho. The tyoes of test conducted with carrying this S7O00A state of By , " A Seas “4 7 au thao dl Entel wn Wd oe examining some aspectes of the Spm system of opea tion, Plants derived A a from the newly appearing variegated class off kernels on the ear produced tle wit tub 79 by the cross of 6078-5 by 6080C-7 were also examined, ome of them WEEE A ad o& ml state 57008) / a, and others wee a "1 (state 5700A)/ amt (state A Wc Ween Cod 5719A-2). Bebe sta beg Vaoveared Qn the progeny of phants having this \ Porhuler — duruy the pDureel wb latter constitution, each hesieg retained its own properties we€ie togetrer A A Qn in the nuclei of ome plant. Hurkhex Discussion of the manner in which mobo these tests wergme de will, be postponed until the methods adopted for them may be considered, oN 85 Besices the intercrosses of ~lants carrying the distinctive states of av n by m- tha a . ay 1, described above, crosses were mede betweer plant ing the 2 2 le py ole Lt Me s + a ney 7 iL Te - ” 4 original soste of ay in one chromosome § and a, in che honologue, with 2 plents having one of the following derived states: state 5716, state S7194-1, and state 5720. Tho—ts+08-of kernels an scaring -on—ttre ees $ROS6—H+OSSE S cwsakod Mauls have produced willnespe-corstaered litre in-tteteil . As steed earli the "A Odum Loe, Carrtiug O mudaut Gael, Original state of a m= giveg rise to many cevminet mittens. th dy Thcun. 24 peer the Duclsn o ae ty ua eth Arorned C1vel aul majority of kernels ue plants ths boxe lovee veh—cermminal mucaiton in-—them “OW A Thaw, Upeewe, Li pres muh poe. e f = . ilow 6p sas coe shrte onthe Cena Onel ise | Ut iad Mure WA dy Atouoe etn. exkkhkk lesser prades of, piement intensity bette in kernel and plant Many ollretio, 2a 4-\ thet 2 (oak Dia onde wu ewe Orbuna ns um belo peatol, uthe ye st:uble in the presence of Spm. this OEE oe ae bd ga Ne some kernels ey on ears produced pf Qe, cross’ conducted with oclants carrying state 5718 or ae state 5719A-1 to plants carrving the original sta te of ay Med Before Unda (hoi typao.e Aireurnoih Whipp that oppoor on Lorn poate Ug Uy %, lawl; considering this A o~ " + Lor of: ~tne-enicinal wg ugar mel by peut, Duy, ao {Mr O, Unt ho Of0 Prue state of ay plants that carewihis sto:e-in-one-ehnemesone_2 and a. in.the-hometecues In the swum r of 1951, 48 plants were grown from variegated ke~vnels appexring on ears produced by cross of the original a,™t carrying vlant \ . . . a mw to plants thet were homozygous for aye “hese kernels exhibited a pattern of variegaticn that wos common to most of the variegated kernels produced by 86 ‘ ; . Te . test crosses conducted with the orignal a, 1 carrving vlant (phots de k * a » * 31. 2 4 2 The plants derived from these kernels likewise exhibited the same bizarre types of variegation pattern that charact rized the appearance of the \ ; PAYAL 1 , kernels. ¥t was obvious that cnanee, 6 ay A See occurpeeg in a number Roce Up of cells of the plant and many of thet teeummsd early in stent development. A ta . The plants were composites of distinct sectors in exch of whéch a particular phenotype was expressed, Many of them exhibited the A, phenot: ve, In others, the pigment was uniformly distributed withi the secotr but thet intensity eit was low. Still othsr sectors were distingvished by he ek - distinctive tyveg of vardegsticn pattorng within them, Raumexkxix Sameer bod p, These Weseemressedemaes stre:ks of the AS type pigment in a non-pigmented CL Rirtuck QAY, Oug ahs Abatois ; ep) ober 11 background, oad bhe number and size of these streaks was—not— the sane i Us oum paul Meuclt Vronod “° sectors—exhibiting-tiskinekive yarisgatbdes peattcrns. In a few plants, Aty the type of pattern of vai legationy exhibited by one tiller differed or Lulubn by 4 greatly from mnet eo the main stalk and ef other tillers off thds same A =< e plant, we mhv Some of the variegated plants that were a," /a, in constitution were s used as female parents in crosses with plants homozygous for a5 and sho. The tyes of kevnels appearing on the resulting ears are given in A of table 17. Pollen of two nlants were used on silks of »lants carrying 87 Te a modified state of 2. 1 (state 5718 or 5S719A-1). To serve as a control to—sueh—eresses, part of the pollen collected from each plant was -laced on silks of ears of nlants that were homozygous for are The k +nel tynes on Prudud & bh ¢ Two heut wut paceole jy timers-c ears) are shown in B of table 17, In this baole, the kernels thet ronan tay. Q wou "Xs yy? ° a4y A, tm-phonsiee are vlaced under the heading"A,". Under the heading of tate" are placed those ko»nels tht were uniformly Beet v2 ypeseee dy. lana pigmented but in which the intensity of xhks was lower _then—thetrreduced Gano aby Bernt sho iosate oo Witnin this class, thebew-os_a range in intensity,from very faintiy VA pigmemted fn-some keeneks to meddium dark fex others, All ke-vnels exhibiting variegation for anthocvanin pigmentation are entered under the had both heading "variegated", Most of these kernels — large &ndsmall Oud tofiies ones, oY b> ~~) areas with the Ay phenotype amd pale wrens Gl the last colum of this | A A ust ad \ ‘ table are entered the number of ko-nBls expr sseHe a markedly altered A : pattern of variegation, similiar in types to those iret bse tea o—miare A altered states that have been considered in previous sectinns, It may be seen that the number of them is low. However, other changed states, less easy t' detect, were being produced, Cne of them was detected oo. pawl because it was present in t@@e cell whose descendent cells gave rise to an th” , AN ear ‘Aheet had been used in a cross with a plant homozygous for as ahd sn, A 88 The pattern exnressed by the variegated kcrnels on the resulting ear was me) 1 « of one type and it diff red from that given by the original state of a This similarity in patt»:rn made it possible to know that an altered state was present in the cells that gave rise to this ear. In the presence of Spm, this altered state produces many small A, dots, located very close to each other, and also some larger areas exhibiting the A, phenotype L (Photo. ). To the naked eye, some kernels having this pattern of variegation may anpecr to be uniformly pigmented, itlowever, mieewscopic examination of them reveals the pattern of Ay svots that is resvonsible for this deception. The dots of A are so close together that there distinctiveness can not be seen except when viewed under magnification. (In all studies of voriegaticn, kernel trpes on ears are exumined under magnification in order that details of imoortance in them would not be undetected.) In the absence of Spm, kernels in which this state of a is present have pigment in them, but this is so light in intensity that detection of it sometimes is difficult. the tyroes of kernels on the ear ot the original plant having this state 5996-K are given in © of table 17. In plant 5996-4, one Spm was present and it was carried in one of its two chromosomes 6, (See footnote to table 17.) 89 On the ears produced by crosses of plants that were a m= (original 1 state)7 a, to plants that carried either state 5%18 or 5719A-l/a,, the original state of many of the kernels that received/a, + gor a mutent derived from it, could be recognized. Likewise, those that received ay from the plant M1 snd the derived state of a from having the original state of ay the other parent also could be recognized. This may be seen from the photograph of kemnel tyres appearing on one such ear (photo. ). However, Hernels with a tkukinekkxy new phenotype appeared on these ears. They had the vettern of A, dots given by the derived state of at but pale these appeared on a/pigmented background instead of a colorless backgr und, This suggested that the plant carrying the Origioal state of amt had contributed a mutant of an giving a reduced grade of pigment intensity and that this mutant was stabe in the presence of Spm, Tests of vlants derived from such kernels indicated the correctness of this interpretation, In other words, the original state of aut was giving rise to mutants that were stable in the ‘resence of Spm, Some of the pale mutants vroduced by the original state of amt that are stable /in the presence of Spm very much resemble in their phenotyrvic expression that given by some of the derived states in the absence of Spm, “his is strikingly illustrated by one tyne that resembles that produced by state 90 5719A-1.In the absence of Spm, kernels having state 5719A-1 are deeply pigmented whenever Pr is present in them, However, when the kormels are hom zyrous for the recessive allele, pr, the kernels are only lightly pigmented, some of the stable mutants derived from the original state of amt give these same phenotypes with the alleles of Pr, “t would appcar that the production of either a stable mutant or a new state by m1 the original stete of ay is associated with the fate of the controlling mi element at the ay + locus, “ts removal or total inactivation cculd slight give rise to the stable mutants whereas a/shift in its location, without inactivation, may be resvonsible for the origin of scme of the altered states, It is apparent, nevertheless, that the production of steble mutants by the original state of at is far more frequent than the production of abviously altered states of the types that have been described in this report, In the cross of al (original state)f/ a, by at (state 5718 or 5719A=1)/ ay, the kaa Spm number was known only OBA ol in the plant carrying the derived state, The Spm number in plants h:ving A . the original sate could not be determined readily from the tyves of kernels add ced appearing on ears produced by testserossss conducted with t+, The A frecuency of occurrence of germinal mutation was too nigh, Nevertheless, 91 the the types of kernels appearing on the ears produced by/tress of »lants carrying the original state to vlants carrying the derived states, whose constitutions were given above, is instructive, and the tvnes of kernels appeiring on six ears produced by this tyre of cross will be given. There was a total of 2175 kernels with the followi-g phenotypes: the 277 with/A, EXpKESsinny phenotyoe, 71 that were uniformly pale colored and fle had a derivative of the mrxwinnixekakexerxn md some of these obviously MEXRXRBYiMNRiyXeExixedx fran the originel state of m=] and ay introduced by the parent mving it, Eighteen other kernels were uniformly pale colored but supperimosed on this were dots or spots of AL with a pattern given by the derived state of a me used in the cross, 1 There were 1207 variegated kernels that fell into two distinct classes? 602 exhibited the pattern that is charactcristically produced by the Me] original state of ay and in some of these, the presence of the derived state was suspected, and 605 ‘wxxkteexkedxke that exhibited the dots or charact*ristically produced by the derived state and spots of A, /in what appeared to be a colorless background, In addition, there were 602 colorless kernels. Tests of plants derived from kernels exhibiting the variegated patt-rn of the derived state ona pale pigmented background, and those derived from ones in wiich both the original state and the derived state were suspected to be preset, confirmed the suspected constitutions of the kernels from which each was derived, From the former, the presence of a stable mutant in one chromosome 3 and the derived state either 5718 or 5719A-1, as the cese may be, in the other chromosome 3, Plants derived from the latter tyre of kernel had the original stave of Mea] 2 1 s 4 s 4 + ay in one chromosome 3 and the derived state in the other, lests of aut behsvior thet have been discussed in detail in previous sections of tuis resort were all conducted during the ecrly vo riod of m= . . a 4 . study of ay ° From them was developed an interpretation of the primary mode of operation of the system responsible for control of gene expression m= J. + +s . mel at ay . The origin and behavior of diffe-ent states of ay were considered, and the discovery of an independently locted element, Spm, whose mode of action was outlined, was likewise treated, Vevertheless, 7 2 = Te 1 2 L 7 oe * up to this time in the stud: of ay » ho previse tests of this interpreta- tion had been conductsd, The interpretation that had been developed implied the following conditions. Spm is an smiupendtenkkxxkoxrkedxekememkxx is the indenendently. M1 located element in the ay systom, anc it is subject to transposition from one location to another in the chromosome complement, In its presence, change occurs at the a, ml locus and this may lead to one of two matin consequences. One of them results in a stable mutant expression, iv # ch musant cx Presses one mode of gene action, recognized by the degree and A “ ose ote ; ria anthocvanin and kind | offoigment that iepreduees in plant and kernel. The second : ; me , easnits in an altered state of ay 1, evcn state expression thereafter one pa’ ticular type of -resonce to Som. This is related to control by the 4, m=] altered ay itself of the time during development when subsecvent change will occur fio it, the tyoes of mut nts that these latt r chanres will induce, and tre number of cells in wnich such events will occur, The nuriber of Spm elements present in the nuclei of a vlant or kernel does not particular mel most alterthese qualities of a/state of ay . In the absence of Spm, & states of ywiy4 REARRXRR ay functiong in the production of anthocyanin pigment in both of pigment plant and kernel, and again, the type/and level of its production fazuniz mpenxkhex is a quality of state of aw This function is suppressed in plant and kernel the when Spm is present in thenuclei. Removal of Som from axzumxkikme nucleus potentially n+l ef a somatic cell will allow the/functional activity of &he stave of ay that is present to be exoressed in its descendent cells, : : eas : 3 * The above statements incoroorate the primery conditions imposed by the.?! y ae e. nee ‘i + . ji ¢ Cel : s c * inteorpretaticn, Mere 6vidence was-requited-in order to test the general ‘ Xe a. ° Wh CE Qty, ial Ateeleb aX ale a *® validity of tnis interpret ation. " Therefore, such west’ were conduct < aot ws aren a Tee PSs at during the summer of 19h. There wore many such beste and toy + will be the Ly bee, subject of the section of this revort the ° A” ey Oh \V srupscalan Bebabishment—of—the Voridttay of the interpretation of mode of a 7 : a. operation of the Spm element Qurh 7 tho am bluseelsly 4 ayadu 4, The interpretation of mode of control by Spm of gene expression at -1 ay » Outlined in previous sections, required precise verification, and tests devided for this purpose were conducted during the summer of 195. The interpretation considers that no Spm is present in the uniformly Pravncrtcd pale cetessd kernels on ears derived from crosses entercd in tables 2 to pes bay, 8 and 10 to 15, but that it is present in all kernels exhibiting pigmented A areas in a colorlesg background. Ig also considers tnat each state of m1 oc Up stun az L will respond to any isolate of Spm in -@ manner , Ret s cha reetertstic of—_the—state, In..other. words, it will be the state ef-aq rl —that-will ; An geole & govemn the pabtern.of variegation. a Lo illustrate, if ppollen of a plant homozygous for a, and carrying 1 Spm 1] 28x is placed on the silks of a number of plants, each derived from a pale A . . ep 7 m- colored kernel and in each of which a different state of ay 1 is present, * . : sud on on the’ ear produced by each plant, 2, elt of the - a carrying kernels snould Bb wk musty VTi Miptneling othe ate abe fray Darwen g Sat oT pg! parent. be pale colored and half should be variegated, , On each ear, | tee patter “A 4 * week ou peerite tdi, OW otic } ila, Ww 1) ic jy “pend iy phy l¢ of variegation andng the variegated. kernels should | expres. ) eRet—whieh is A y iat anil anthle | & re are Characteristic of ‘che State of a,mi x present in the ear bearing plant, If the pollen parent should have 2 xnwExEnienktx non-linked Spm elements , 95 LUBE Jf then on each of the resulting ears there should be a ratio of one pate rte dm colored kernel to 3 variegated kernels among the a Canpying lcoonels vA wy iy OAL catid heer who erut ut lid and again, tne pattern exhibited By "som should be that Ebwed by the state of a, @t 1 that is present. Several tyoes of test-cross were devised that made it possible to learn whehter or not Spm wer: present in any one plant, and to demonstrate trduytelu pi ti OE FA cen me-1 with certainty the oonbecl of pndnctine by stater of ay , Pot in the “Aye tap presence and absence of Spm. These were conducted during the summer of 195h. Theplants to be tested were derived from selected kernels on eazs i produced by crosses made in previous growing seasons. the types of kernels selected, the number of plants derived from each type, and the origin of the ear from which ean selection; wit’ made, is given in table pisist cel 18, All kernels desived from one ear were grown under one culture number, that entered in the last column of this table, however, the a4, otf. RHXANXETK “MOU WIE a alias , kernels of each class/imxkakiexk& were separated.£rom one-anethen, amt A Letéer-ot-tie atptrebet. If other genetic markers alwo were segrega .ting fy . BALE HC, WLR OA Vs gn Deel fae JouwtL bewdaF one _ among the kernels on the ear, all teese wkkkxkiexxamm phenotype were 4 sown Ag sa paundie Uroan arg Ereum separately from those Weh-enother, each given the same culture A Out gto hp Be number but appropriately distinguished by a letter of the alphebet following they ettuxe number, A - 96 The most critical types of test-cross were conducted with plants reréneixt te three different categories, The plants belonging to the first of these were unif rmly pigmented, They were derived from pale each “4 whch colored kernels on tee self-pollinated ears of plants/haghiwes one Vw particular state of at. A Bach of the tester plants in this first aad uth on - L category was homozygous for te particular state of a, i that was present in the parent plant. They were also homozygous for Sh Within this 2° category, four different states were represented, and these are given in w a won. ~ part I of table 19, The culture number of each from waich their origin oa my , ott oy ye oO ph. 4 “Ty. < . o"~ may be traced through table 18, as-welt—as thee constitutions with regard to genetic markers carried in chromosomes 5, 6, and 9,are also Siven in this table, ; aft fii is tee << If the plants in part I of table 19 are used in crosses of the A following tyres, only pale colored, sh, kernels should apverr on the resulting ears: (1)Crossed with plants of the standard a,/a, tester stock, (2) Self-pollinited or sib-crossed . > ~r s 4 . . wth PALES 7 Ue AVMEN TI ORE od (3) Intererossed with plants in the same e:tegory bringing together two dirferent statesol Qym-t, A (1) Crossed to vlanits derived from the pale class of kernels in teble 18. 97 (5) Crossed to some of the plants derived from the colorless, sho chris. d 4 cultures entered in kernels in/table 18, hg ya If the plants in part I of table 19 are used in crosses of the quia Lileus, foitowing typ Dey both pale colored, Sie, kernels and variegated, a, kernels should appear on the resulting ears: (1) Crossed to some of the plants derived from the COLOTLOS Spain Vav. ly kernels in cultures entered in table 18, (2) Crossed to plants derived from the variegated class of kernels in are cultures of table 18 in which the constitution of the plants 7¢ a," 1 Sh/ a, sh, e QY From cross (1) immediately above, all the variegated kernels on the a pattern Aude ues Uc lint resulting ear should exhibit/that, i expected to be produced by the state of a,™1 present in the tester rlant,. Areas, Wf one ear of the a,/2, plant received pollen from a tester plant homozygous for one state of m=] 1 and another ear of the same plant received pollen from a tester m=] plant that was homozygous for another state of ay » then among the variegated / kernels on BHEXBAXZ each ear, a distinctive pattern cf vaziesatien s ould Quai 4 ies qbautcalsa Kita vibe y Ort rong these poms 4 be expressed, one pattern on one ear and another pattern’ on the other A aufherisve WA card 2 Taye oh Loeb, ear. The pattern im-eaeah would ee the individual | response of the a ’ state of a," contributed by the tester stock | te the presence of the same Spm element. A 98 From type-cross (2) immediately above, two class of variegated kernels whould appear on the resulting ear, One should exhibit the variegated patt.rn produced by one state of 7 superim-osed onver m= that produced by the other. These would be the kernels receiving By from each parent. The second class should exhibit only the pattern that is produced by the state of ant delivered to it by the tester plant, and What these kernels would be those/receivthe ay from the plant being tested Ov ae! fn thy bow ead: On the ears produced by the type-crosses described above, it should , be possible to detcrmine the Spm number in that part of the paant that produed the ear used in the cross, This could be deduced from the ratio of pale to variegated kernels that appearson the ear, Also, if the plant being tested were heterozygous for one or more of the genetic markers in chromosomes 5, 6, and 9, given in table 19, then the location of Spm with respect to these markers could be detcrmined, provided that Vitis HOM et da— “Ure . AER? ollie fe EY the tester plant, » these markers, were—henesygaus A PeRGeHat¥e, aA b - . me Ulan 200 - Wi Bh URUAG Tre-deseribed test_crosses Were conducted with teste: oclants im—tke ote eutrte se entered in part I of table 19, From the j a Vounu ue kernel types on the resulting ears it was ~ossible to ne presence or absence of Spm in many plants, WHese phenetynes were knowny ay LEY a : fe vents Manet Ont ty Covrciart ie, Utell Cho leno q Hep plmul,aitlen oncoated on werforl, Meal \9 oO hue pou eto dtoume | bbws also, when-present, the number of Spm elements thah were present in A any one tested part of a plant. In many plants it—was—aiso—peossibie—o deeexutime the location of Spm with reference to the three given genetic Myra CT Mr anef! markers, Fr in chromosome 5, Y in chrom: some 6 and Wx in chromosome 9, 4 oa the different m1 These tests also senvedete confirm the individuality of /states of ay ge prove in tne’ control of pattern of variegation in the presence of Spm and, tye of roe ATV hag aotiwee 0 y gene expression giveg in its absence, Before evidence ofthis—ts oA e presented, the usefulness of tester plents in each of the two remaining categorics will be described, For some types of test, it would have been desirable to use plants that were homozygous for both a,™"+ ana sh At the time, no plants of 1 2° 9 Pp this constitution had been constructed, Therefore, kernels that were a, mt sh_/ ay sh, appearing on eass produced by the crosses entered in tables S and 8 were select