GENETICAL STUDIES IN CULTIVATED RASPB]~Pd%IES

I. INHERITAN@]9 AN]) LINKAGE i

]~:~ D. LEWIS Jo]ua I,m~es Hor~ic~,aa~.ra~ I~*s~it,{~lio~b Mergogz

(With ?]ate VIII)

CONTENTS

1. In~redue~ion 2. ]JnherR~nee of fl'l{.lividuM characters 3. Linkage 4. [Discussion 5. Summary , .. 6. Aclmo~dedgemen'ts

I{eferenees

2kQ~

367 a68 a74 876 377

• . ave 378

1, INTRODUCTION

T ~ genedea.I investigation of the cult ivated raspberry to be described in this paper is a continuation of work begun by l~[r M. 3 . C~ane in 1920. In 1981 Crane & Lawrence published a description of five genes, %we con- trolling fruit and spine colonr, two sex and one hairiness. In the present paper five new genes controlling morphological characters are described, and a statistical analysis of all gene segregations is made. All the recent data have been combined with those already published, for wbicll I am ranch indebted to ~{essrs I%{. 13. Crane and W. J. C, La~rence.

Much of the material used has been descr{bed before, but six new diploid varieties have been used in recent years. They are 13um]ett Holme, Hornet 1{, Norfolk Giant, Preussen, Red Cross and Winkler's Seedling. All these varieties have most of the characters in the dominant condition, but they proved to be heterozygous for a number of genes. I t is f>on?. these varieties tha t the new mutants have arisen. [Burnett I-Iolme is heterozygous for seven out of the ten known genes, and even the var ie ty Lloyd George, which was found as a oh.an.co seedling growing in a wood, is heterozygous for three. I t is evident f rom the early horticultural records t ha t the heterozygous condition has persisted for some time. Parkinson in 1629 mmations the white- and red-fruited and spineless forms, I t is

i This papm' is an abridged part of a. %hesis (presmited in ~'ebruary 1989) approved for the Ph.D. degree of the Univ'ersit.y of London.

368 Ge,zeaica[ £%diea i';z C z~Ztivc~ec~ Bc~.sloberriea

the prolific natu.ra[ vegeta¢ive reproduction of the raspberry which m~in- rains their kete.rozygoas condition. In wild populations of raspberries, individuals with all the dominant characters commonly occur; the sub- glabrous form, ho~vever, is quite common, and the recessive yellow- fl:uited and male forms occasionally occur.

There are diploid, tfiploid and tetraptoi& varieties of raspberry. L~ the genetical work triploids and tetraploids have been used only to a limited extent,

2. TI-IE IN~[EIglTANCN OF INDIVIDUAL OE[AIZACTNRS

£%:c 9e~zes F, f mtc( lW, m

As the phenotypic expression of the two genes affecting tl~e sex organs has been described fully by Crane A Lawrence (1931), only a summary will be given:

F, normal female organs, normal pinnate leaf. f, aborted female organs, undivided leaf. 2~, normal anthers, normal leaf. m, contabescent anthers, normal leaf. The data are summarized in Table I. The segregation is within the

limits of expectation except for heterogeneity in M, m F~ families.

TABLE I

Negreqa~{o~ for tke c.ye.ne~ F, f c~,~d lye, m T o t a l o f 2

TogaI of 6 Toga1 o f 3 backoross /~a fami l ies F f //'a famil ies M ~ }Rm/lies 1VI r n

694- 537 167 567 432 1:~5 289 152 137 X" D.m P X ~ o .~.. 5~ X ~" n .~. P

Dev. 2-0922 1 0 ' 2 0 - 0 ' 1 0 0. , i285 1 0 -70 -0 .50 0-778,5 t 0 ' 5 0 - 0 . 3 0 ~.et. 9.2125 .5 0 .20-0 .10 6.,9929 2 0,0,5-0-02 0 .2806 1 0 -70 -0 ,50

In the families summarized in the table the segregation of sexual forms is wall defined and sharply discontinuous. However, strains have been obtained, which approach an intermediate Sex condition. One strain, under the name of ~¢Iabbey's Seedling no. 2, has the obtuse leaf like the t~:ue male, but the flowers are not completely sterile (see P1. VIII, fig. 6). A similar strahl was recorded by Focke (19tl.), who states that R~.d~e~s i&~e~s var. obt.~.~a[fe~h~s forms occasional seeds from which weakly plants have arisen. Another strain h~s been found which has a normal five-lobed leaf, no anthers and poorly developed female o}gans. In this strMa the female organs are more developed than in the true lnaie, but mot completely so, as in the hermaphrodite and female. The genetieal consfiltut.h~n of these intermediate foe.ms is not yet lc,mwn.

D. LEWlS 369

I-IcKry shoots (t-I), sub�lc~brous shoot~ + (h)

The segregation of hairy and snbglM)rons shoots is given in Table II.

TABLE II

Segregations for the 9e~es I-I, h

To~al of 15 seH'ed or in~ercrossed To~I of 17 ho~erozygo~e b~ekeross

families tat h l:amilios 1649 1126 523 1311

Dev. 39.3369 1 <0"01. 0.2204 ?flog. ~3.1t97 t4 0-10-0'05 15.9891

I-I h 06-i 647 o.~,'. P

1 0,70-0,50 16 0.50-0.30

The data show that while ba.ekcross families agree well with tt~e expected t : I i'atio there is a large but consistent deficiency of haky plants in F~ families, k deficiency of the dominants was found by Crane & Lawrence (1931), who pointed out that the proportion of hairy to sub- glabrous plants closely approximated to a 2 : I instead of a 3 : I ra~io. To emplain this anomaly they suggested that the homozygous dominants might be suppressed by a te~hal gent. In support of this hypothesis was the fact flirt 71o hom, ozygous hairy plants had been discovered either among/v= plants or varieties. Out of the nine varieties which had been tested, four were heterozygous hairy, and five subglabrous. The work of Grubb (t935) also confirms the general conclusion but he found even a higher proportion of subglabrous varieties in the East Mailing collection. One family raised by Grubb gave 81 hairy to 6 subglabroua, a significant deficiency of subglabrous plants. This suggests that the homozygous T.eeessive is also suppressed by the lethal, and in this case h and the lethal gent are in the coupled phase.

Since 1931 three liomozygous hairy plants have been found among fourteen F 2 tested hairy plants. Two of these homozygous plants were found in family 9/27 {Lloyd George seIfed, 69 h~iry to 20 subglabrous). These were the only plants which were tested in this family. It is probable that Lloyd George does not carry the lethal, and the close approximation to a 3 : 1 ratio in the selfed family from Lloyd george supports this view. From fhe remaining families one homozygons plant found out of twelve tested is considerably lower tha~. the expected one-third, but agrees well with the expected proportima on the linked lethal hypothesis.

J often, of Genetics xxxv~ 24

370 ge'r~etical Studies i~ Cultivated Ba~pbe~'ries

Colou,r 9e~es P, p a,~l T, t

The two main genes affecting the colour of the fruit and spines have been described by Cr~ne & Lawrence as

G e n e t y p e Sp ines F r u i t P T ICed ge d p T Tfl~gad l~ed Pt G r e e n A p r i c o t ? let C--±-een Yellow

The genetical difference between apricot and yellow fruits was only tentatively suggested by Crane A Lawrence. Evidence confirming th.eir view is given in Table III. Whenever a PP plant is used as parent uo yellow-fruited plants are found in the progeny, and when the factor P is

TABLE Ill

Genetic constitution Spine- r~d , tinged green green F a r o , no. o f p a r e n t s fZrtlifi-red r ed a p r i c o t y e l l o w

9/31 Ttpp selfed -- 122 -- 35 -- 117'75 ~ 39.2.5

5/36 T t P P self~d ~8 - - 19 - - 50"25 -- 16"75 - -

7/36 T t p p sewed 63 -- 7 -- 52"5 -- 17-5 --

8/36 T t P P solfed 3"7 --- Ii - -

36 ~ 12 9/36 T t P P x T t P P 31 - - 4 - -

26.25 -- 8-75 - - 2/32 tiPP x TtPP 25 -- 28 --

26-5 -- 26-5 -- 10/36 T i P p × T t P p 40 5 ot 4

~9 '75 9 '93 9-93 3 '31 26 /36 T t p p × T t P p 25 IS 6 1

16-5 16.5 5-5 ~ 5,5

TABLE IV

Sey,reg~io~ ]o~" the yeues P, p

To~l of ,t F~ f~n~Llles P p

610 ~69 14;I X ~ ~).~. P

Dev, 1-1569 I 0"30-0 .90 I-£efi. 3-1706 3 0 -50-0-30

not prese~$ in either of th~ parent% no ~pdGot ooloured fruits are found. I{owever, there is a certain amounb of variation in t£e depth of eoIour of the apricot and yellow fruits. This variation is probably due to other genes which have LOt been identified.

Data on the segregation of the genes P, p are summarized in Table IV, which shows that there is no significant devistion from expectation and no heterogeneity,

D. LEWIS 371

The extensive data on the segregation of the genes T, % are sum- marized in Table V. There is considerable heterogeneity in i#, and rome heterozygous backcross families, but female heherozygous backcross families a r e homogeneous and without significant deviatiml from expectation.

TABLE V

Segregations for lhe ge~,es T, t T t D.~. P

To~al of 38 2 , families 3925 I297 . . . .

D ev i a t i o n " - - - - 0-0738 ] O,80-O-qO He~et-ogeneity - - -- 153-6621 37 < 0 - 0 I To~al of 4 d' he~ecozygous baokcrosa 235 186 - - ~ - -

f~milies ]')eviagiop. - - -- 5-7031 I o-0~o-0l l:Ie~erogenei~y - - - - 23-0435 3 <0.01 T o t a l of 4 9 hegerozygous baokcross 202 t98 - - - - - -

f~milies Dev ia t i on - - -- 0.0400 I 0-90-0-80 Fre~erogenei~y - - - - 4,6131 3 0.30-0.20

Since there is homogeneity in the segregations in female heterozygous backcross families, the heterogeneity in other segregations is not due to either fault}, technique or miselassification of the genotypes, and the cause vdlI be considered in a later paper.

Stem, spine¢~ S--spineless s

This character can be seen shortly after germination. Tile spi~ed plants have stalked glands on the cotyledons and young leaves, whereas the spineless plants are devoid of them (ef. Rozanova, ]934) (see PI. VIII, fig. 5). An analogous case has been found in Rubus rustica%us (Crane & Darlington, 1927). The stalked glands appear to be morphologically equivMent to and the forerunners of the adult spines. The data given in Table VI show that t:t~e ahsence of qines is due to a recessive gene. Segregation is normal and homogeneous.

TABLE Vi

Segregations for the genes S, s Faro, no. S s X = 2

t./32 and 2/33 Bm:net, f H o h n e (Ss) solfed 340 119 0-2008 0-70-0-50 13/35 ~ u r n e t t Jdolme (Ss) sclfed x 36 41 0-3246 0-70-0.50

1-25/32 (ss) 1.1/36 Burne~t H d m e (Ss) se.Ifed x 68 65 0.0676 0.80-0.70

I - 2 - 1 1 / 3 2 (ss) 15/36 Z-1/33 (ss) x .Burnetg t t o l m e 9 21 4.8000 0-05-0"02 26/36 1 -2 -11 /32 x B u r a e t t X o l m e 90 86 0-0909 0.80-0-70

T,q~at of ba .ckcross /hmiHea 203 213 0-2403 0,70-0.50

t l c t e r o g e n e i t y x ~ - - 5 - 0 4 2 8 , ~ ,F . - -3 . P=0"20--0 '10 .

24-2

372 Gene~ical S tud ies in Cult ivated Rash)berries

JStem, bloomed B--without b~oom b

The wild-~ype raspberry has the young canes covered with a waxy b~oom. In ~hese eXl?erimengs the only varieties found to be heterozygous for this character are Bnrnett Holme and Winkter's Seedling. Only one variety is known to have the recessive character.

The character is very easily classified when the plants are mlbglabrous (hh) ; the wktbe bloomed canes contrast markedly with the greta bloom- less ones. When ~he plants are l~firy (H), more care mus~ be take~ when scoring, for the hairs partly mask the bloom. The data showing th.ag the bloomless character is due to a recessive gene are given in. Table V[[. Apart from one family, 26/36, there is no significant deviation from ex- pectation and no heterogeneity. However, there is a tendency for the heterozygotes to be clefieien~ in the backcrosses.

TABLE VII

Seyreqat.ion.s for the genes B, b Selfed hegerozygotes B la X a J).F, P

1/32 and 2/33 Burnet~ l-lolme 362 126 0.1748 i 0 ,70-0,50 1/33 Winlder ' s ,Seedling 14I 61 2-9108 I. 0 .10-0.05 4/36 2-1/33 76 35 2-5255 1 0"20--0-10

Toga.1 579 222 8" 1 4 9 8 1 0" 10-0-05 He te rogene i ty - - - - 2 . 4 6 1 3 2 0 - 3 ~ 0 - 2 0

Backeross

13/35 Burnegg Ho lme × 1- 6 14 3-2000 I 0-10-0.05 25/32

11/36 B u r n e t t ~Iotme x t - 2 - 34 45 1,5316 I 0.30-0-20 iilaB

26/3G ]=2-11/32 x Burnett 32 57 7.0224 1 <0-01 H o l m e

Term 72 116 I0,297S t <0-01 He te rogene i t y - - ~ 1,5405 2 0.50-0-30

Lec~f, dar]~ green G--i)ale gree.;.~ g

Several di:fferen~ .types of chlorophyll de:ficiency have been. observed in the raspberry, but only one, pale green leaf, has been investigated

'I![o~erogenei~y

TABLE VIII

~Seyregations fo~ the 9enes G, g Tota,l of -i 0 he,~m:o-

One d' he~erozygous zygous b~ckeross Te rm of 24 F~ families baekcross lkmiJy fami l ies

G g G g" G g 1756 3,57 I07 40 845 321

l ,~ D.~'. d ~ X ~- D.lv, P X ~ D .F , P

74.0218 1 <0.01 56.1125 ]. <0-01 0.8648 I. 0.50-0"30 [0~.3503 23 <0,01 - - - - - - 6,7938 3 0 .10-0-05

D. LEw~s 373

genetically. This dharaeter ]1as been described by Grubb (]935), but unfortunately his data were not sufficient to allow a genetieal analysi,a to be made. Pale green leaf is dne to a recessive gene. Table VIII summarizes the data on the segregation. There is signil~ca.nt 1,eberogeneity and deTia- tion in F2 families and deviation i1~ the one male l~eterozygous backeross family, but the segregation in the female heterozygous backoross families is normal and homogezaeous. This is exactiy tee condition wlHeh was found in the segregation of T, t.

IIy2oool, yl, 9ree.~ X--red x

This character is transitory and can only be scored between the first and third week after germination, The red eolour, which is due to the presence of anthocyanin ia the epidermal cells disappears, when tlle seedlings are a few weeks old. The genetical evidence for its inheritance is not eomplete, bnt R is probable that the red hypoeotyl is dne to a re- cessive or incompletely recessive ge~e. The evidence is given below:

Burne~g I~olms selfed

1 2-11/32 × Barnet t lgolme

selfed ] ! ,

Green I~ecl Green ~ed 71 19 102 43

Three of the red plants were sewed and all bred true for the red hypoeotyl colour, three green individuals on se]fing produced families which segre- gated approximately 3 green to 1 red.

In some families two types of red were found, one more in~ense than the other; this may be due to incomplete dominance, The fact that when the less intense reds and greens niche are segregating they are in an appro~mate 1 : 1 ratio shows tha t the less intense red is most probably the heterozygote.

F~owers, ~orma~ D--seFaloid d The normal flower of tke raspberry }~as five sepals and petals and

numerous stamens and carpels. When the variety Burnett Holme was selfed, apl?roxh~aa~ely one quarter of the offspring had sepaloid flowers. Tlae degree of sepaloidy ~as very variable and almost conq)J.ete transition was found from normal flowers to flowers, the petals and stamens of which had been replaced by sepals. However, th.ree main ~ypes of sepa- loidy could be distinguished: (I) one whorl of six sepals instead of five, normal number of petals and anthers; (2) two whorls of sepals, one whorl of petals, a~thers reduced in number; (3) ~hree whorls of sepals, petals

374 Ge~,etica~ Studies in C'~dtiva~ed R~s2Jbe'rri~s

absent, and a]]thers absent or very few in number (see :Plate VIII, figs. 1-4). Sepaloid flowers were found previously by @rubb (1935) and a form was described by Foeke (1911), under the name of Bubus fdaeus war. y)hyL lanthus, as having leafy cones instead of flowers. This answers to the description of the more extreme form of sepMoidy.

Some variation, in the degree of sepaloidy between flowers on the same plant was found, therefore when classifying the plants five flowers were examined. The range of variation found is given in Table IX, and the genegical history of the character is given in Table X. The variety Burnett Holme, which has notarial flowers, when selfsd produces tmmnal and sspMoid plants. If die different types of sepaloid plants are included in one class, they form approximately one quarter, This variety when crossed with one which is homozygous for normal flowers produces only normal plants. Sepaloidy appears to be due to a recessive gene for which Bnrnett Holme is heterozygous. So far no explanation can be offered for the few normal plants which appeared among the progeny of a sepaloid plant (faro. 11/35, Table X) nor for the deficiency of normal plants in backcross families.

TABLE IX Plant no. No. of sepals in five flowers Class

i 6 6 6 5 5 2 2 6 7 6 6 '6 2 3 7 5 5 5 5 2 4 5 5 6 5 5 2

TABLE X

The se.qre.qation of se,ffcdoidy Class... I 2 3 4

Two whorls Three whorls Normal Ext ra sepal of sepals of sepals

1/32 Jhurnett I[olme :B6I 29 34 46 2/:33 selfed 261 ~ w +

109 2.5/36 1-2-11/32 (Class 3) selfed 0 ,~ 1.8 8 26/36 B m ' n e ~ Eolme x 1-2-J.1/32 14 81 36 6 11/36 recip. L~/35 1-25/3Z {class 3) sel£ed 9 26 0 7 13/35 Burnet~ [~olme × 1-25/32 12 ;t8 9 3 4/36 2-1/33 (class 2) selfed g 51 13 0

15/36 2-]./.33I:< :Buruet~ ][{olme 1 15 6 1 X ,~ for families ]./32 and 2/33=3.92-L D.~. - ' I . 2 = 0 " 0 5 0"02.

,3. L ~ { A ~

Evtdence h'.~s been obtained that :four of the ten known.genes in the raspberry are linked in one groap. These genes are T (red, pigmentation. of fruit and spines), B (bloomed stem), G (green leM') and X (green

D. L}~;wIs 375

hypooo~yl). Information has been obtained on the £dlowing combina- tions TB, TX, T G and BX. The data on %hese four linkages are given in Table X. t t will be seen that the linkage Z" is highly significant in all cases excep~ II and X. However, there is Little d,oub~ tkat these genes are not independent since T is linked both with X and B, The whole of the a*ailable data are given exce]?~ for TG, in whick two female heterozy- gous bat \cross falnilies have been selected because F~_ and ~nale hetero- zygous baclccross families show distuxbed single fa, ctor ratios. The cross over values and bheir standard error~ ]save been calculated by various methods according to the type of data. The values for the/ 'our linkages are given below:

l){e~hod T;B 28'4 q-2'9 % NTaximum likelihood 1 TX 20"0 ±6.9 % Prodne~ TG 18.2~:~°'1% Exact method / ~'Iather, .1938 BX 36' 7 ~+ 9.0 % 3ia.ximum likelihood )

TABLE X I Linkage TB

TB Tb tB %b

( T B ~ 0bserved 197 28 41 31 Burnett ~0hne selfed \ / ~ Expected 167"0625 55"6875 55"6875 18"56~5

Linkage X"-=32'1070, ~),F.=I, P = < 0 ' 0 1 .

TB T1) tB tb

Burne~b Hohne \ ~K] 1-~-11/32 \ ] t b Expected 50-625 50"625 16'875 16"875

1.-2-t1/32 selfed ~X

1--2-11/32 x Barnett ~olme ~ -

Lloyd George \~-j

2-8-6/32 ~-G) x 2-3/32 \ t g /

>sq]./32 {~xh bx ] x Bm'ne~t

Linkage X2=9.3343. D,r,=]. P = <0"01. L inage TX

TX Tx tX Cx

Observed 48 18 32 1

Observed 46 22 21 1

Term 94 40 53 2 Expected 106-3125 35.4375 35-4375 11-3125 Linkage Xz=I6-5132. D.F.=I. P = <0,0t.

Lflakage TG TG Tg tG tg

Observed 69 14 13 80 Expected 44 44 44 44 Observed 16 63 54 16 Expected 37-25 37'25 37 '25 37-25

Linkage X~=301-5376. m r . = l , P . - <0.01,

Li~kage BX BX Bx bX b x

('Bx~ 0bsm'ved 2t 12 43 11 Holme \/~':K Expected 32-625 10'875 32.625 10'875

Linkage X = = 2.3947. DJ. = 1. P = U'20--0"10.

376 Ge,~ze*iced £Y~dies i~a C,zLZaivcaaed Ras2)b¢,v'ie8

4. Discussion

Ib has been shown that the gene tI (hairy shoots) is almost oomplel~eIy suppressed in the homozygous condition. The evidence for this conclusion. is that backeross famihes segregate in the expected 1 : 1 ratio, whereas selfed or intererossed hsterozygo~es segregate 2 : 1 baby to 1 sub- glabrous. It is not possible to state with certainty whether the in- viability of the homozygons hairy plants is dan to a linked lethM or direetly to the gene H. The fact that the homozygotss are viable in certain strains and that a family raised at Eas~ Nailing showed a large deficiency of the reeessives indicates that a linked lethal is the cause. Whatever the cause of the lethality of the homozygotes it affords an explanation of the fact that the subglabrous form is common in some wild populations (of. Grubb, 1922), It would have been of value to determine the percentage of subgtabrous forms in wild populations; this is unfortunately often impossible because of the difScutty in distinguish- ing individual plants, However, in some areas, if it is assumed that the rate of vegetative reproduction of the two forms is the same, the sub- glabrous plants represent as much as ]~alf of the population..

The only geas in the raspberry which, from experimentM evidence, is known to have a higher selective vane in the heterozygous than in the homozygous condition is also the only gsne which is polymorphic in the wild. This supports Fisher's (19.30) theory that if the heterozygoge is at a selective advantage there will be polymorphism.

A similar exampte of inviability of the homozygote in other pIants is the Punjab hairy lintlsss cotton. The homozygous limtless was at first in- viable (Algal & I¢~tchinson, 19.33). After eight generations a fnlly viable homozygous lin~Iess %rm was extracted (}Iutchinson & gadka,ri, 1937). Two possible explanations given by the authors for ~his change were (I) a reverse mutation bringing the homozygots up towards normMiV, and (2) the action of seleotion on the hetsrozygotes. Both suggestions are admitted by the attthors to depend upon t~nlikely assumptions. A more probable explanation is that the i~viability was not due to ti~e lin:ttess gene but to a tightly linked lethal as in the ease of the hairy raspber.ry. The heterozygous plant from which NI]Z viable homozygous l.intless offspring were obtainedcot~ld then. be simply explained as the result of an occasional cross-over. The original lintless plant was found in a field of cotton, therefore it is it.or necessary to assume that a mutation of the ffntless and lethM genes occurred simultaneously.

Sepaloidy in raspberries, ~s in oth.er plants, is not inherited in a

D. LEwls 377

simple manner. _~lghough i~ would appear that one basic recessive gene is responsible, 6here is considerable variation within the sepMoid class. This v~riation may be due either go the gene having a weak penetranee or to a number of modifying genes. The variation in the degree of sepaloJdy in Oe~ogt~e~'c~ bie.~z~'is cr~dc~.~ has beelL explMned by Oelkers (1930, 1935) on a number of allelomorphs, whereas l~enner (1937) offers the h)qooth.esis that there is a single pair of a]letomorphs, the sta-bitity of which is dis- turbed, when the plant is heterozygons for them. The cause of the variation in expression of such a character may lie in the instate of the character itself rather than in any genetic modifiers. The organization of floral parts may be governed by a regular distribntion of a particNar substance in the bud primordia. I f the organizing system breaks down as the result of a mutant gene decreasing ~he amount of substance, then disorientation of primordial tissue will be the result. 11 p~"fori, lack of organization will result in variability. This may be the anderl}Jn.g cause of the widespread variability in the degree of se]?Moidy and doubteness in flowers (ef. BeaUty, 1937).

A statistical analysis of all gene segregations has shown that the segregations of the genes T and G are heterogeneous in P~ and male heterozygous baekcross families. Baekerosses in which flue female is the heterozygous parent are normal and hoanogeneous. In other words, heterogeneity is present only when the particular gelae T or G is segregat- ing on the male side. Segregations of all other genes are homogeneous, ~herefore both faulty technique and miselassi£catJon of phenotypes as the cause can be ruled out. Since linkage has been demonstrated between T and G, it is evident that there is a common cause for the heterogeneity of these genes.

5. 8UM~A~,Y

The five new genes which are described are: s, spineless shoots; b, shoots without waxy bloom; x, red hypoeotyl; g, pale green leaf; d, sepaloid flowers. Additional data are summarized on the genes es$ablJshed by Crane & Lawrence (193].).

A statistical analysis of M1 gene segr%ations shows that there is significant heterogeneity in the segregation of the linked genes T and G when the male parent is heterozygous, but not when the female only is heterozygoas. Segregation of all other genes is homogeneous,

The proportion of hairy I-I to subglabreus h individuals exhibits a significant deficiency of hairy plants when a 3 : 1 is expected but not when a 1 : 1 ratio J.s expected. Instead of a 3 : 1 ratio there is a good fit to

378 Genetical ~5~h~dies in O~dtivated Naspbe~'ries

a 2: 1, and addbional evidence supports, the conclusion of Crane & Lawre~lce tha t the homozygous hai ry forms are pa r t ly suppressed by a t ight ly linked lethal. This affords a~ explanatim~ of the fac t t h a t tile ha i ry subglabrous characters a]:e the only pair which are po lymorphic in bhe wild.

One linkage group of four genes is described.

~. ~kC KNOWLEI)GEgIENTS

t wish to express m y sincere gh.anks to Mr ~[. B. Crane for gt~e use of his .material and for continual interest and help in the work and to Dr X. l~ather for criticism of dm statistical analysis. I a m i n d e b t e d to i~Ir N. !~. @rubb of the Eas t Mulling Research Stat ion and to ~ r J. t{. S. Po t te r of the P~oyal I-lorticultural Society 's Gardens, Wisley, for some of the original p lants used in these experiments.

1;tEFEI%ENfJES

AFzir., ~f. & ~r~em~-~so~, J. B. (1933). "The inherRance of 'lintless' /n _ & s i a ~ f c

cottons." Ind.ian Y. Attic. Scl. 3, 1124, 1132. ]3~.x~TY, i . V. (1937). "A s~tistioM s~sudy of flower doubling in Eschscholtzia cal f

fornica @ham." Geneticc~, t9, "4~7-64. C~.l~, 3'2[. ]3. & D~a~L~@TO~, C. D. (1927). "The origin of new forms in 2~ubus."

Gens&~, 9,241-78. C~i_~:~, ~I. B. & L.< wr~s~es, W. J. @. (193i). "Inheritan.ee of sex, colom" and halriness

in th~ raspberry, l~uSus Idaeus L." J. Goner. 24, 243-55. FIs~c~R, I~. A. (1930). iv]~e genetical Theory of NcLbu~ui S~ection. Oxford Univ. Press. Food=v., W. O. (191I). "Species Rub~.ru,m." Bi5l. Bet. 72, 208-9. C+~crs~, ~NL H. (1922), "Commercial raspberries and their d~ssificatlon." J. Pc.reel. 3,

1t-35. - - (I935). "Raspberry breedlng at East~ MM[fng." J. PomoL 13, 108-34.

I-Iu~:c~r~so~, J. B. & £4ir~Ki~:% P. D. (1937). "The genetics of lh~lessness in Asiatic cottons." J, G~net. 35, 161-75.

~Ia~m~, X. (I938), The Measu.rement of Li.n/~ags in Heredity. London: Me~huen, 0]~L17:~r~,% F. (.[930). "S~ud/en zu.m [Problem c~er Polymer{e and des multipbn

Al~Momorllism.,~. tL" Z. BoL 23, 967-1003. - - (I935). "Die Erbl~chkMfl der SepModie be[ Oenothera trod Epifobium. I I t . "

Z. Not. 28, 16t-222. Pa~,.~se~, ,A (1629). Pa, radisi in. ado Paradi,sus Terresbris. London. ]~.Na~:~a, O. (I937). "0bet Oenot'herc~ abrovi.rens Sh. & ]3artI. und iiber Somagisehe

Itlottvecsion im Erbgang des craciab~-MerkmaIs der Oenobheren." Z. i.ndukt. Abstc~mm.. u. VererbLehre, 74, 91-124.

Rozt~ovi, i~. (193-t.). "Con~ribn@on to ~he cluestio~ of geographieM and oecologic~0 var.h~tien of ch'araeter~ as- shown in 5.he ins~:~mces of several represent~adves of the gener~ Rubus and F.ragaria.." Bull. aTFL Bet. 8, no. 2, F.ruRs and smMI frM~s.

D. LEWIS 379

E X P L A N A T I O N OF P L A T E V I I I

tTig. L Flower wi~h one ex~r~ ael~al a,nd pe~M (type 1). 3 x n~t. size. Fig. 2. Flower wi th no petals, few ~nthm:s and ~,wo whorls of sepals (~yl~e 2). fi × us,t, size. Fig. 8. Flowec with no pegMs, no anthers and thr(*e whorls o~ sepMs (type 3}. 2 × nat. size, FN, 4. Flower with n o pe, tMs, two whorls of aepMs and s tamens changed to otufles.

3 x nat. slze. Fig. 5. Cotyledons of spiny and spineless seedlflags showfl N the presence and absence of

gI~ndul~r hMrs respectively. I~ xna'~, size. ]rig. 6. Leaf~ flower with pctMs a.nd anShers removed ~md fru/~ of a weak female s~ra.in. The

fruit has nine drupelets; fruits of hermaphrodites and ~naales have 70-g0. Nat . size.

I a.m indebted {,o ~{z' }I. O Os~ers~oek for tile 1)hotogr~l)hs.