PLANT MOLECULAR BIOLOGY REPORTER Volume l, Number q, Fall 198 i, pages ;()-~1

E X P E R I M E N T A L P R O T O C O L S

Suggestion for Efficient Recovery

of Visible Mutants V i r g i n i a W a l b o t

Departmo~t oJ Bto/.L, aa] S~ an, c.,. Stan/}Jrd Unwer.~lt), StanJr, r,t CA 9-~ ~ 05

Max,m,z,ng recovery of a large number of independent mutants is a malor factor ,n deslgn,ng muta tmn experiments Coe and Neufler (1977) discuss possible strategms particularly as apphcable to ma,ze They calculate the ef-

ficKenctes o( treatments as mutants recovered per number of plants grown assuming that the mutagenesls created mutants with 25'7 effectiveness and

that there are 16 cells of a dr)' seed whose progeny will produce gametes (Table l )

It ~s clear that selfing of M1 plants ~s more effioent than outcrossmg and

that plcklng an appropriate s,ze of the M2 populatum (,n th,s case a single

kernel per M1 ear) ,ncreases the efficmncy of the procedure l fpol[en muta- genes~s ~s possible, this procedure is as effioent as the most efficmnt seed

mutagenesls and allows observatmn of segregatum m the M2 rather than i%1 ~, popular mn

A further refinement of these procedures would be to recngmze wh,ctl plants (M2 of seed treatments, Nil of pollen treatments)are heterozygous fi)r v,slble

recessive mutants befi)re selfing the entire populat,on tt) observe the subse- quent generatmn My suggestmn ,s that these putatively heterozygous seed

be gamma- or X-~rradlated prmr to planting to generate chromosomal losses that w,ll be v,s~ble as sectorzal chmleras of mutant t~ssue on the plant. For

example, ~f pollen were treated w~th mutagen and used on normal ears, the resulting M t seed would be X-,rradlated When the bl l seed are grown into

O//~,t,lt ,equtJtJ t~, \qrgmla \ ' ( ' l l bo t

3o

Su~,,gcst;,,n /;,r l:Tfi, tent Re~oro 3 , f Vtsthk ,'Hutants 31

plants there s h o u l d be sectors of pred,c table s,ze resul t ing from chromosome

loss events ,n the ap,cal me t , s t em cells of the qmescen t embryo. For ma,ze,

these secturs are typical ly 1/16- 1/40 of the leaf wid th and ~ .,-* u of the ear or

tassel (Coe and Neuffer, 1978) An)' plant that has a wslble sector of wh, te ,

yellow, al tered morphology, e tc . , would be selfed with the expec ta tmn that

in the M2 progeny there would be ~.1 segregatmn of normal and whole

seedhng m u t a n t types For a plant wt th few g c n e u c markers , this me thod could be used to qmck ly

genera te a co l lec tmn of readily scored vls,ble muta tums . The method would

also save considerable work m species Jn wh,ch e , ther outcrossmg or self-

po l l ,ha t ing requires h igh techmcal skill This method m ,gh t also allow rec-

o g n , t m n of mutan t s that are lethal m the homozygous c o n d m o n , such as

albinos These mutan t s can be rescued by embryo cul ture and are very useful

~n tissue cu l ture exper iments

The malor hm~ta tmn of th~s me thod ~s g t w n g an approprmte dose of X or

g a m m a - r a d m t u m to induce sufficmnt chromosomal loss to v~suahze the mu-

tant md,v ,dua l s of interest Dur ,ng 198";-1984 we plan to test the efficmncy

of th~s procedure m uncover ing color variants m matze and wdl report the

results when the expe r imen t ~s fimshed.

TABLF I.

,'*lut, m . . Sta' . f ,112 ,Xlutant~ po Traam, nf 31 l 0 .~, T,, he Sd/ed Plant~ Grou n

on st.t.d .ut~ross large () 08 on st.t.d self largt. 0 16 on st.t.d st.lf small () 25

on pollt.n st.lf 0 25

Acknowledgment This work was suppor ted by N1H grant G b l ~,2-i22

References Cot., E H Jr and M G Nt.ufl~'r (1977) The gent.u~s of corn In C.rn and C,.~1

hnpr.tement(2ndt.d) G F Spraguc(Ed )Am Soc Agron blad,son, Wl, pp l l l - 223, st .epartlcularlypp 196-20t

Cot', E H Jr and bl G Nt.uffi:r (1978) Embryo tells and thtmr dt.stmmes in the corn plant In Tk~' Cbm, d Baft~ . f l)etvbJpment, S Subtt.lny and l bl Susst.x, (Eds), Nt.w ~lk~rk Acadt.mlt Prt.ss, pp l 1 ~-129

R.en,aUum, 5. I98