7'
L il e Golden fge of Corn Lerietics at Cornell

as seen throu& the eyes of l4. 15. Rhosdes

   L.aize iknetics at Cornell began in 1914 r;r!len H, A. iherson came from :u'ebrzs!ra

to ~I.XCI tLle iiepartment of Plant Sreedling. Bli~>hZSlE in those earl;? days WAS on

sg& Fd" Q'i c
      - -  gencti.c problems as tine location ol' numerous unplaced ;;enes, factor

interaction, establishment of li:lkaEe groups, linkage raps, pericarp varie~:ation,

the inheritance of gametoph;,tic cnaracfers, the genetic basis of semi-sterility,

etc.  IbtGrson's m7sterf?ll zna!.~rsis 0:': -the inilerit,ance of plant colors did more

thm any other single pzoer to plnce m ,aize Lenetics on a firm basis.  l~'iU.Cil wEtS

learned at Sornell about the com;7ositi.on ,ud architecture of the mai.ze genome by

Zmerson, Iiutc l-ins&;, i)emercc, 5. f. Anderson, Xndstrom, '$rstcr, Sprague, Pill;.pps,

Li, Yrunson, ?re;ger, Fr:?ser, among &hers.  The irnnortance of these early

investi q? ,,.tS.ons cannot be over-elph?sizcd. They set the state for the remarkable

advances in c--fiogenetics which follor.red.  The c+ogeneticists stood on the shoulders

of iheir predecessors.

  Prior to the ~:!d 19233, little c~tolog;lc;ll work was done -&.th paize, which

was not regarded as favorable cytological material. This WDS an erroneous con-

clusion.  I'cClintock, using the carmine sIneRr technique invented by Belling,

found -tWt the pach$,ene clro:osomes could be accurately identified by length,

Erm ratios, and heterochromatic knobs in specific locations.  Xaize was an excellent

organism for both cytologic:~l and genetical studies and the combination of the two

disciplines (cytogenetics) qllickly led to a large number of significant studies.

iviaize cytogeneticr L) may be said to have begun in 1929 when ilcClintock~s paper on

triploid maize appeared in Genetics.  T'nat progress was explosive in the ne,xt felr

years is evident from the follow?.ng account of the advances made in the subsequent

six years.


-2-

  The status of maize cytogenetics bar the mid 1330's was sumnarized in the


paper by Zho?dcs and !;cZlintock published in The Botanical Review in 1935.  The

acco~ylishments described helo:; were largely taken from that paper althouyh a

r'rx research fi:idl"gs, more ~enetical than cy-togenetical i.n nature, are included.

The names of the investS.,-ators rnsyonsiblc r'or eac'n advance are indicated i.n

'Sf Txtheses.  Capital letters designate those individuals who were tra:.ned or

xere postdoctoral ?ellovs at Cornell.

1.







2.







3.



14.

5'.

6.







7.

8.

9.

10.

Il.

            `Tile Status of Naive lenetics in 1935.

The esta'nllsirxrt of ten linka~~e groups corrcsyondinz to the 10 chrol.jososles

OP tnc haploid co;nnlement.  (Cooperative studies by many, mostly American,

geneticists).

The association of each linkage group rtitrl a particular, mo~~~~i~olo~ically

identifiable member o:i:` the chromosome complement,  (IWXIUTOCK, Brink, 2nd

sUR;TlLUr ) o

The placement of specific genes at definite nositions ltithin the physical

chromosome.  (13cCLITiTOCK and others).

The c;tioT!.c$cal proof o.? genetic crossing over (CFEI%TOFT and McCLIYTOCK).

Cy-tolo~ca.1 and genetic proof of chromatid crossing over (14cCIJ~~JTOCK, I'UOr?D:33).
Cytological deterrrination of the physical location withi.n the chromosomes of

reci-orocnl trnnslocations , inversi.ons and deficiencies.  (:~C~~:P~T~CK, smxm,

Brink, CiE`CI ~LdT(x Y F%O:DX3, V. H. FXOADS).

The genie control of chromosome behavior.  (9 ADLS, NcCLIJTTOCK).

Proof that c1hiasmata are poi.nts of genetic crossing over.  (EmDLE).

Nonhomologous pairing and its genetic consequences.  (I:cCLII`ITOCK, Stadler).

Instability of ring-shaped chromosomes leading to variegation.  (McCLINTOCK).

Divisibi-lity of centric regions. (PIcC:J::T~CK).


12.

13.

lk.

15.



16.

17.

-5-

Corr?lntS.on of hetcroiJycnosis with geneti.c inertness.  ( I?A!`IKt FH) .

P.rtifical production of pol:rgloidy.  (XAIiDOLFii).

13k;Lgenic effects oi" X-irrad:.ati.on.  (Stadler).

C~tolo$.cal and genetical analysis of Zea -3xhlaena hirbrids (Z!W?SOK, 3311LS,

iianS~lsdor.: and 3eeves).

Cytological studies with Zea-Tripsacum `hybrids.  (ilm~elsdorf, Reeves).

C,+onlasrdc male sterility. (REO.PD'S).

  The above com$lation indicates the prominent role that Cornellians played

in the development of maize cyto~enetics.  'The period from 1929-1935 was truly

tile Colden Age of i1aize Crenetics at Cornell,  The aci:ievemeiits of the Cornell

gl-OUP i.n the 1920'~ 33d 1930'~ WFS unrivaled b/r any other constcllat.on of y1an-t

Seneticists and :.~a3 second only to the famous Drosopiljla school under Iiorgan at

Columbia,

  kdding to Cornell's reputation was the establishment at Ithaca of the

Faize Genetics Stock Center for the maintenance end distribution of genetic stocks

and the founding of the Xaize 3enetics Cooper;2tion News Letter, in wiiich appeared
unpublished data unselfishly contributed by geneticists at many institutions.  This

unique cooperative effort was so successful that it became widely copied.