Lcctu-e 4, January 18, 11!$$. t;" I, Previous discussi&: 1, Located factor res::onsible for chromosol?,e losses 1 to 2 crossover units to right of Wx. 2. 'he of genetic markers in chromosome 8 short arm: `i 0 l&y- ui; ' y 1 ;:pr i -.I. ." -: -=:~-Ly-.~.- ._-_?. . _-. ~._. ~~ 3. Distance between Yx and centromere -- short arm, more than 1/3rd the length of 4. Previous evidence and that of Langley and Ande-son: crossing over between Wx and centromere more than 47; . 5. This suggests that factor responsible for losses is in short arm of chromos!>me 9, a tiort distance from Wx locus. 6. Evidence presented indicating to occur. that a second factor necessary for losses This jnherited independently of factor in short arm of Chrcjmosome 9, Given symbol of AC, a). AC must be in nucleus for losses to occur. b). If AC absent, no losses, no obvious evidence of presence of factor producing losses, II. How does factor in short arm of chr--r;osome 9 jming about losses of chromatin in presence of AC? What occurs at tilis position in tie chromosome? 1. Piece lost is gross. Should be able to see it or see evidence of its loss if sporopytes examined in plants carrying it,, 2. This could be done if losses occur in the sporocgtes themselves, 3. Evidence for such losses obtained from examination of r-ollen of plants carrying factor in Wx chrcmosome: Be&-n page b, section IV of previous talk - outline \..p * `Wd * pl. *f!The inheritance behavior and the mode of action of AC - I, Presence of separate factor, needed for breaks to occur at Ds, suspected from early inheritance studies of Ds. II. Many studies of inheriLm b6nce behavior of AC conducted. Select exam:~les to serve as illustration of methods used. 1. Xish to start this with T>lant h::ving CcnstitutZon 11 C Sh wx Ds AC - Re c sh Wx ds ac 4. Sequence of crosses: On Board. b), Gametes produced by N C Sh wx Ds AC Re e sh Yx ds ac- plants: I N C sh wx Ds AC ' 3:i Re c sh Wx AC `21 If ac h) II ac 2, These plants self-pollinated. Kernels on ear: C Sh Wx, non-variegated C Sh %Jx w3.th areas of c wx C Sh wx -- (normal and with holrozygous deficient tissue) c sh Wx 3. The consitutions of the c sh Wx kernels -- or plants derived from them: _I_- ~-L~-~-~~,---.--,...` j ._ / ./., _ i r<.L"&TGl AC AC : 2 AC ac : 1 ac ac, ,, e_C-C--- _ .*I. f lohLt4 \rbhsy _Iw_M- I-w . . . . ~-~Y*..ll*l.s~lC.-**I,I- -... - __ ,_.-. ,_, .__ 4. Must have method for testing for presence 0:" AC: Development of Ac- tester stocks. III. Develonment of AC tester stocks* 1. ?he N C sh wx Ds AC Rec.shWxds 8c plants used as male parents to Re c sh ~Jx ac Re c sh Wx ac Male gametes: -lo kgQ,.&g 2. a Y-a-br . . ,. _ ' . ..-~ / N C Sh wx Ds AC t---------.----- i N c Sh wx Ds ac ' r ' Re c ih 1;Tx ac Re c sh Wx AC Re c sh Wx ds ac Re c sh Wx ds &:nel phenotypes: C Sh Wx, areas C Shti of c sh non-var. c sh Wx c sh Wx 3. The C Sh Wx, non-variegated kernels: N C Sh wx Ds ac Re c sh Wx ds ac 4. Pla-nts grown from them. These self-pollinated: C Sh Wx, non-variegated C Sh wx N C Sh ti Ds ac Re c sh Wx ds ac I W N C Sh wx Dsac 2B 8 Sh wxDs ac c sh rZrx Ret sh Wx ac Re c sh Wx ac 5. The fJ C Sh wx Ds ac N C Sh wx Ds Tz An AC-tester stoc& How used: 6, Assume Ac/ac constitut?on of plant with c / c constitution: Gametes: c, AC ; lc,ac x G Ds, ac gametes: F ear: 1 C kernel with c areas : 1 C kernel, non-variegated; Assume AC/AC constitution in c/c plar,t, &metes: al.1 c, AC. Plant crossed by C Ds, ac tester plant: All !~rnels on ear s:hould be C with c areas* Assume ac/ac; c/c const4tution: tester stock: all kernels: all gametes c, ac. Crossed by Ac- 4 I-I"' C Ds / c ds. ac ac. All Colored, non-variegated, 8 IV, The tests for AC in'plants derived from c sh Wx kernels in back_cross E: - 1. Expected ratios of AC: 1 Ac/ac : 1 ac ac (See diagram of crosses). 2, The test cross: a). hernels selected; plants grown from them; crossed by C Sh wx Ds 7- 8c C Sh wx Ds ac (1) Results: 180 plants tested: _, : :., ;3? 904with 1 to 1 ratio of C 31, llix non-vu. to C Sh Wx, areas of c sh, 2;-" A. ~: $: ."; 9O,. All kernels should be varie,c;ated if plants we%e AC/AC b) . 'orne kenels non-v:.riegnted as shown by pllotograph. why ? Table 5 a, AC account, ----xz= ? iL& i ': ;-` ' 7 < : VII. Tests of AC illlLeritance in c sh Wx/c sh WX AC Ai plants: r - &"> r', 1, Besides baross by C Sh wx Ds, ac tester, some ~~lants also s3&$3qz&%mQ crossed by Re c sh Wx, ds , ac tester stocks. 2. Expect all gametes to be Re c sh d"Jx, AC. if cro ssed by (3 Sh wx Ds ac testor stocks should,get all plants with. ears in which ratio of varl to non-Var~3.s 1 : 1: Female gametes Hale gametes: Re c sh Wx ds, AC i" C Sth wx Ds, ac -A--x= All ears should show this ratio Gbscrved ratios. Ears obtained from 96 plants. - On 95 of them: 1 C Sh ?,dx non-var. kernel to 1 C Sh Wx wZth c sh area on 1 ear: All kernels non-variegated. No evidence of AC 4. Question: What hasha???ened to AC? constitution? Yhy is one plant ac/ac in VIII. Return to ears produced by c sh Wx, ds, AC/AC plants, Photo: 1. What is AC constitution in the kernels that show no variegation? 2. The tests of these kerrlels have shown what happens to AC z d why it is absent in some of Z;'ne kernals and also in some of the rjlants derived f0om AC/AC plants, Will be discl:ssed next perio'd, ?.I IX. Review of evidence of AC inheritance: 1. Statistical rat+os in backcross: "2 F 1 AC to 1 ac foz;nd. g: All AC/ AC in self of A$'Ac plant 1 AcAc : 2 AC ac : 1 ac ac found. Not found 1~. All kernels on ears of AC/AC plant: should s&or: brekas at Ds 1 plant in 96 &&no AC .' not fornd. A few ke nels with no breaks -- no AC?*