MARDI Res. Bull . , (1984) 12, 1: ( l t6-t28)

MODES OF INHERITANCE AND LINKAGE RELATIONSHIPS OF

SOME DISTINCTIVE MORPHOLOGICAL CHARACTERS IN CHILLIES(CAPSICUM ANNUUM L.)

B.H. CHEW*

Keywords : Morphological genetic markers, linkages, Capsicum annuum.

RINGKASAN

Di dalam pengajian ini, sebelas ciri-ciri nyata morfologi, genotype cili dari berbagai origin telah

dikaji dan cara perwarisannya ditentukan. Rangkaian telah didapati dalam tiga pasang ciri. Hubungan di

antara ciri morfologi yang tertentu (contoh 'pubescence') dan kemungkinan ketahanan pada perosak

telah dib incang. Penemuan oleh penyel id ikan yang terdahulu drcatatkan bersama dengan pengaj ian

masakini d i r ingkaskan di Jadual I 5.

INTRODUCTION

Chill ies (Capsicum spp.) are members

of the Solanaceous family originated in

South America. Malaysia is one of the major

consumers of ch i l l ies. Annual import ot

dr ied chi l l ies runs in to mi l l ions of dol lars.

There is no distinctive variety grown

commercially, the local cultivars are mainly

Capsicum annuum L. There is a wide diver-

sity of characters existing in the farmers field '

This substantial genetic variabil it ir forms a

good basis for a selection programme to

improve the relatively unimproved cultivars

presently cultivated in this country. Few

breeding works have been reported locally

(SoH, Yee and GRAHAM, 7916, 1977; Mer.

ZAINoL ABIDIN and Sou, 1981). There is

only one report on the genetic of disease in

chil l ies (SoH er al., 1977). No genetic study

has been carried out on the morphological

characters which are of great value to the

breeders in thei r se lect ion programmes.

This paper reports and discusses the

results of some of the crosses effected to

gather information on several distinctive

morphological characters as regards to their

modes of inheritance and interrelationships.

MATERIALS AND METHODS

three exotics, were used. The contrasting

characters studied, together with the origin

of the materials are presented in Table l.

Before hybridization was carried out,individual plant of each genotype was selfedfor one or two seasons to ensurehomozygosity of the characters under study'

The cross combinations selected for the

present studies are given in Table 2. The

seeds for the Ft and F, generations are

obtained under plant house conditions. The

F, plant populations together with their

respective parents were planted at MARDI

farm in Serdang. Seedlings were trans-

planted one month after sowing. Plants were

spaced 60 cm apart within and between rows

on raised beds. About 10 g per plant of com-

pound ferti l izerof formulationN : P : K : TE-- 12 : 12 : l7 : 2et were given two weeks after

transplant and monthly henceforth.

Pesticides and fungicides were used when-

ever necessary to maintain healthy growth.

Chi-square was used in testing the

goodness of f it of expected genetic ratios-

For l inkage analysis, MATHER's (1963)

procedure of l inkage detection was adopted.

Respective chi-square values were obtained

for factor pairs and linkage, giving the three

components which added up to a total chi-

square testing for g : 3 : 3 : 1 ratio. Linkage

intensities were estimated by maximum like-

l ihood method (FISHER. 1946).Five genotypes, two local cultivars and

*Central Research LaboratoriesDivision, MARDI, Serdang, Selangor'

1 1 6

Table 1. Genotypes of chillies, their origins and characters examined

HairGenotypes Origin

lnter- Laminanode

Colour Fruit colour Fruit shape

Inter- Nodenode

PetalBase

Immature Mature Straight Curve Tapered Round

+

+

+ - D G R +- + c R +

i f

+K5

+ +

- i

l i

R

Y

Y

SY

G

G

SerranoTempiqueno Mexico

Malaysia

Cili PutihKelantan Malaysia

Thai Yellow Thailand

LlC22 India

NB: + denotdprcsneofthccharactcr.- dcnote 8b6cn@ ofthc charact€r.DG - dark granG - grccnSY - sulphuryyellowR - red

Y - ycllow

Table 2. Hybridizations effected forthe present studies

Cross No. Parentage

In the F2 populations, the crosses involvingglabrous parents, viz. Cili Putih Kelantan(Cross No: 81006), Thai Yellow (Cross No:81007) and LIC 22 (Cross Nos: 81009 and81011) showed a very good fit for a threepubescent to one glabrous segregationpattern for the expression of internodal andleaf laminar hairs (Table 3/. Pubescence oninternodes and leaf laminae is conditioned bya single dominant gene. Linkage analysisshows that twd different loci are involved(see section under linkage studies).

Immature fruit colour

Genotype Serrano Tempiqueno hasdark green fruits as compared to the lightergreen fruits in Thai Yellow and LIC 22. ciliPutih Kelantan has sulphury yellow fruits. Inthe F, populations, the proportion of fifteensulphury yellow and one green individualwere recovered (Cross No: 81006 and 81008,Table 4), indicating that double dominantgenes are controlling the expression ofsulphury yellow fruit in Cili Putih Kelantan.In crosses 81007 and 81009, the segregationpattern of the F2 populations gives a verygood fit to a ratio of three green to one darkgreen individual (Table 4). Dark greencolour of Serrano Tempiqueno is a singlerecessive character.

8 r001

81006

81007

81008

81009

8101 I

Serrano Tempiqueno x K5

Cili Putih Kelantan x SerranoTempiqueno

Thai Yellow x SerranoTempiqueno

Thai Yellow x Cili Putih Kelantan

LIC 22 x Serrano Tempiqueno

Serrano Tempiqueno x LIC 22

RESULTS

A. Mode of Inheritance of Some Morpho-logical Characters

Hair (Pubescence)

Thick hairs are found on the internodesas well as leaf laminae of genotype SerranoTempiqueno. The other genotypes eitherhave very fine hairs hardly discernible withnaked eyes, or glabrous. In the'four combi-nations (Table 3) examined, all the F, plantshad hairs on the internodes and leaf laminae.

r17

Table 3. Goodness of fit tests for pubescence character of F, populations

Cross No.Pub.

Plant part (Ui or H1)Glab.

(hi or tr1)Genetic

ratiochi-

square ProbabilitY

81006 Internode

Laminar

81007 Internode

Laminar

81009 Internode

Laminar

81011 Internode

Laminar

66

60

5 1

48

48

46

54

52

1 1

L J

15

18

8

10

15

t7

3 : 1J : I

3 : 1

3 : 1

3 : 1

J : I

J : I

3 : 1

0.9036

0.32s3

0 . 1 8 1 8

0 . 1 8 1 8

3.4290

1.5238

0.0048

1.9915

0.25 - 0.50

0.50 - 0.75

0.50 - 0.75

0.50 - 0.75

0.05 - 0 .10

0.10 - 0 .25

0.75 - 0.90

0.10 - 0 .25

NB: Pub. - pubescenceGlab. - glabrousHl and Hr denote alleles for internodal and laminar pubescence re.spectively.hi and h1 denote alleles for internodal and laminar glabrousity respectively.

Table 4. Goodness of fit tests for immature and mature fruit colour in segregating F2 populations

CrossNo.

S. Yellow(CY1cr2;

Green

@YIcv21GeneticRatio

chi-Square

Probability

81006

81008

81007

81009

81008

81009

81007

74

7 I

D. Green(cs)17

9

Red (Cr)

J I

25

29

5

6

Green(cc)37

38

Yellow (cr)

1 6

5

5

0.0008

0.3120

1.2099

0.8583

0.7617

I, I1I2

r.9216

0.95 -0.99

0.50-0 .75

0.25 -0 .50

0.25 - 0.50

0.25 -0.50

0.25 -0.50

0.10-0 .25

1 5 : 1

1 5 : 1

NB: S. Yellow - sulphury yellowD. Green - dark green

Mature fruit colour

Fruits of genotypes Thai Yellow andLlC22 mature into yellow colour. The othersare red. All the F, plants of the hybrids(Cross Nos: 81007, 81008 qnd 81009)between parents of different fruit colour hadred fruits. The F, segregated into a propor-tion of three individuals having red fruits and

one having yellow fruits (Table 4). Theyellow fruit colour at maturation of ThaiYellow and LIC 22 is a character controlledby a single recessive gene.

Colour of petal base

Most genotypes have Pure whiteflowers, except in K5 which has a purplish

118

tinge at the base of the white petals. Exami-nation of the combination 81001 showed thatall the F1 plants had pure white flowers, 4ndthe F, segregated into a porportion of threeindividuals with pure white flower and onewith purplish tinge at the base of the petals(Table 5/. This character is controlled by asingle recessive gene.

Node and internodal colour

Genotype Serrano Tempiqueno hasstrong purplish colour on the nodes but noton the internodes whereas K5 has strongpurplish colour on the internodes only. Inexamination of the cross combination 81001.all the F, plants were found to have purplecolour on internodes but absent from thenodes. The F, population segregated to givea proportion of one individual with nodalcolour and three without, indicating thatnodal colour is a single recessive trait (Table5). The reverse is true for internodal colouras a proportion of three individuals withinternodal colour and one without wasobtained. In this case, one major dominantgene is responsible for the expression ofpurple colour on internodes of K5.

Fruit type

Genotype Serrano Tempiqueno bearsmedium size fruits which are straight andtapering at the ends. Cili Putih Kelantanbears very large and long fruits, but normallycurved and rounded at the end. Hybrid

between these two genotypes had slightlycurved fruits and tapered at the ends. Thefruit size was intermediate between the twoparents. The F) segregation pattern (Table 6)conforms to three curved to one straight andthree tapering to one rounded ratios,indicating that curved and tapering fruits aresingle dominant characters whereas straightand rounded fruit are single recessive.

B. LinkageRelationships

Internodal and leaf laminar hairs

Four crosses involving the pubescentparent Serrano Tempiqueno with the threeglabrous parents, viz. Cil i Putih Kelantan,Thai Yellow and LIC 22 were being investi-gated. The F) joint segregation for inter-nodal and leaf laminar hairs (Table 7) showsshortage of recombinant individuutr lHitt l,ha i rv in ternode and s labrous leaf lamina orh iH1. e labrous in te"rnode and hai rv leaflamina)i No hiHl individual was recoveredin all combinations investigated. There weregenegally excessive glabrous individuals(htht). Analysis according to MATHER( I963) by par t i t ion ingof ch i -square values off ac to r pa i r s (h rand Hr . ; and t i nkage (H t /H t )together with tle heterogeneity chi-squaretest for the four cross combinations is givenin Table 8. The heterogeneity chi-square arenone of them significant, indicating that thefamilies are homogeneous for each com-ponent. The data agree in s.howing goqdi ingle factor rat ios (3 : I for Hih i unJHln l )

Table 5. Goodness of f it tests for pigmentation of plant parts in the segregating F, populations

Cross No. Purple.(cn or Cl)

Green.(Cn or cr)

GeneticRatio

Chi- ProbabilitySquare

81001 Node

Internode

81001 PetalBase

48

1 7

18

49

1:3 0 .1819 0 .50-0 .75

3:1 0.0203 0.75-0.90

white (Cb)

35

Purple (cb)

3 : lt4

NB: CnCr -

.b.b

0.3334 0.50-0.75

denotes alleles for pigmentation on

denotes alleles for pigmentation onnode and internode respectivelythe base of petal.

t79

Table 6. Goodness of fit test for fruit type in segregating F, population

CrossNo.

Straight Curved GeneticRatio

chi-Square

Probability

81006 21Tapered

40

43

Rounded

18

2.0834

0.3334

0.10-0 .25

0.50-0 .75

1 : 3

J : I

Table 7. Joint F, segregation for internodal and leaf laminar hair

Cross No. uiul uirtl ninlniHl

81006

81007

81009

8101 1

60

48

46

52

6

J

2

2

0

000

11

15

R

15

Total I J

NB: Hl and hl denote presence and absence of internodal hair respectively.

Hl and hl denote presence and absence of leaf laminar hair respectively.

Table 8. Heterogeneity chi-square tests for four combinations andtheir respective l inkage values

Cross No. az(flt) lzlsysly DF Linkage value/ax2(Hl)

81006

81007

81009

81011

Total

Deviation

0.9036

0 . 1 8 1 8

3.4290

0.3913

4.9057

3.5474 ns

0.3252

0 . 1 8 1 8

1.5238

0.0048

2.0357

0.0049 ns

2.0308 ns

50.e0

50.97

24.89

52.76

179.52

177 .71* * *

1 . 8 1 n s

0.073 (0.02)

0.047 (0.02)

0.042 (0.03)

0.030 (0.02)

o.oso (0.01)lb

Heterogeneity 1.3583ns

la Figures in parenthesis are standard errors.

lb Pooled value.ns Non-significant.*** Highly signif icant, P very much less than 0.001.

and they also agree in showing linkage of the

two factors as indicated by the highly signi-f icant deviat ion chi-square for Ht/H' .Linkage values estimated bV Fisher'smaximum likelihood method range from3.07o to 7.37o for the four families. As thedata were homogeneous. they were pooled

and the pooled linkage value was 57c with astandard error ofone percent.

Node and internodal colour

One cross combination, viz. 81(X)1 wasbeing studied. According to earlier findings,

120

the genotypes for Serrano Tempiqueno andK5 would be cndclcl and CnCnCrCr wherecnCl denotes purplish node and internodeand Cncl green node and green internode.The t'1. genotype would therefore beCncnClcl which upon selfing gives rise to thefollowing phenotypic classes in the Fr:

CnCi : 9 green node and purplishinternode.

Cnci :3 green node and greeninternode.

cnci : 3 purplish node and purplishinternode.

.n.i : 1 purplish node and greeninternode.

Table 9 presents the observed numberof F, phenotypes in the combination 81001.The segregation pattern conforms to theabove expected genetic ratio indicatingindependent assortment of the two factors,viz. node and internodal colour.

Immature and mature fruit colour

Investigation was being carried out todetermine the association of sulphury yellowimmature fruit colour of Cili Putih Kelantanand the yellow mature fruit colour of ThaiYellow in combination 81008. Similar studywas carried out in combination 81007 todetermine the association of dark greenimmature fruit colour of SerranoTempiqueno and the yellow mature fruitcolour of Thai Yellow. The joint F., segrega-t ion for the d igenic sulphury yel low colourand the monogenic yellow colour would giverise to the following progenies:

^vl^y2^r 1 green immature andyellow mature fruitcolour.

15 sulphury yellowimmature and yellowmature fruit colour.

3 green immature andred mature fruitcolour.

45 sulphury yellowimmature and redmature fruit colour.

gYlgY2"r =

gYlgY2gr

gYlgY2gr -

where Cr and cr denote alleles for red andyel low mature f ru i t co lour and CYICY2 andcy tcyt su lphury yel low and green immaturefruit colour respectively. Table l0 presentsthe chi-square test for the above ratio. The fitis fairly good indicating that the immaturesulphury yellow colour of Cil i Putih Kelanranand the yellow mature fruit colour of ThaiYellow are not in any way associated withone another.

In combination 81007, the joint F.,segregation of the monogenic dark greefrimmature and the yellow mature fruit colourwould produce the following phenotypes:

CgCr : 9 green immature and redmature fruit colour.

Ctcr : 3 green immature andyellow mature fruit colour

cBCr : 3 dark green immature andred mature fruit colour.

cBcr : I dark green immature andyellow immature fruitcolour.

Table 9. Joint F, segregation for node and internodal colour in cross combination 81001

CNCi r.n^l cnCl ^n^l Total

Observed No.

Genetic Ratio

Expected No.

Chi-square 0.2646

36

9

37.r2

1 2

J

12.38

I J

J

12.38

5I

4 . r 2P : 0 .95-0 .99

66

1,6

66

at

121

3 d.f .

NB: Cncn and Clcl denote alleles for nodal and internodal pigmentation respectively

Table 10. Joint F" sesresation for immature and mature fruit colour in combination 81008

Segr. Cr

Segr. CY1gV2Joint Segr.

1cr

lcylcy2 15Cy1Cy2

1.r.y1.y2 15.r6y16y2

3Cr

lcylcf, t5cy1cy2 Total

3gr.y1gy2 45616y16y2

Observed No:

Expected No:

Chi-square 6.9479

J

0.78

a

1 1 . 7 0

2

2.32

36

35.2

P : 0 . 0 5 - 0 . 1 0

50

at 3 d.f .

NB : Cr and cr denote red and yellow mature fruit colour and 6y 16Y2 un6 qY 1iY2 sulphury yellow and green immature

fru i t colour resPect ivelY.

where CB and cB denote alleles for green anddark sreen immature fruit colour and Cr anccr reJand yellow mature fruit colour respec-tively. The chi-square test presented in Table11 indicates fairly good fit to the aboveexpected phenotypic ratio. The dark greenimmature fruit colour of SerranoTempiqueno segregated independently fromthe yellow mature fruit colour of ThaiYellow.

Node and internodal colour and colour of

petal base

In this study, combination 81001 was

being investigated. Serrano Tempiqueno has

nodal colour but devoid of colour at the petal

base. the genotvpe would therefore be

.n.n6'b6'b una tnui for K5 which has colour

at the petal base but devoid of nodal colour,

6'ngn"b.b. The genotypic constitution of the

hybrid would be CncnCDco which is devoid

of the purple colour on the nodt and the

petal base. Upon selfing, the hybridproduces the following phenotypes:

CnCb : 9 green node and white

Peta l .^ n hCrrcu : 3 green node and purplish

tinge at Petal base.

.ncb : 3 purplish node and whitepetal.

n hc"c' : I purplish node andpurPlish tinge at Petalbase.

where Cn a.nd cn denote green and purplishnode and Cb and cb white petat anO purptistrt inge at the petal base respectively.

Table 12 presents the observed numberof individuals for each class of phenotypes inthe Fr . Chi-square test for9:3:3:1 rat io showsfairly:poor fit. Linkage of these two factors is

therefore suspected. The ,l inkage value

estimated by the maximum likehood methodwas found to be 9.3 ! 4Vc.

On the other hand, the genotypes withrespect to internodal and petal base colourfor Serrano Tempioueno and K5 would be

.i. i6b6b un6'6'i6i.bcb respectively. The

hybrid CrcrCDcD has purplish internode and

devoids of colour at the petal base. The F,

phenotypes from the selfed Fr are:

CiCb : 9 purplish internode andwhite petal.

Cicb

.icb

.i.b

: 3 purplish internode andpurplish tinge at petal

base.

: 3 green internode and whitepetal.

: 1 green internode andpurplish tinge at petalbase.

where Ci and ci denote purplish and green

internode respectively. CD and cD as before.

Table 13 presents the number of F,individuals of each class scored. Chi-square

r22

Table 11. Joint F2 segregation for immature and mature fruit colour in combination 81007

Segr. CB

Segr. Cr

Joint Segr

3Cr

9CgCT

1cr

3CBcr

3Cr

3cBCr

3CC 1cBl n f

lcBcr

Total

Observed No:

Expected Nd:

Chi-square 2.8862

22

t9.74

5

6.38

7 0 3 4

6.38 2. r0 34P 0.25-0.50 at 3 d. f .

NB : CB and cB denote alleles for green and dark green immature fruit colourand Cr and cr red and yellow mature fruitcolour respectively.

Table 12. Joint F2 segregation for colour of node and petal base in combination 81001

Segr. cn

Segr. cb

Joint Segr.

1cn

3Cb 1cb

3cnCb lcncb

3Cn

3CbgCNCb

1cb

3Cncb

Total

Observed No:

Expected No:

Chi-square 9.483

15

9

I

J

19

27

13 48

9 4 8

P 0.01-0:025 at 3 d.f .

NB: cn denotes allele for nodal colour.ab danota, allele for colour at Detal base.

Table 13. Joint F2 segregation for colour of internode and colour of petalbase in combination 81001

Segr. Ci

Segr. cb

Joint Segr.

3Cr

3Cb 1cbgCiCb 3Cicb

1c l

3Cb

3cicb

1cb

lcicb

Total

Observed No:

Expected No:

Chi-square 3.261

26

27

I J

9

8

9

1 4 8

3 4 8

P 0.25-0.50 at 3 d.f .

NB: Ci denotes allele for internodal colour and cb for colour at the petal base

test for 9:3:3:1 shows very good fit indicatingthat the two factors, internodal and petalbase colour are not associated with eachother.

Pubescence and pigmentation on node, inter-node, leaf lamina and petal base

Combination 81001 was examined to

gather information on the relationships ofpubescence on internode and leaf laminawith that of the purple colour on internode,node and petal base.

With respect to (i) leaf laminar hair andnodal colour, genotype fo1 . SerranoTempiqueno and K5 *ouia be HlHlcncn and61516'n6n respectively. The Fr, FI1616n.n

I23

which has leaf laminar hair and withoutnodal pigmentation, would produce thefollowing progenies in the F, upon selfing:

Hlcn

Hlcn

hlcn

hlcn

: t hairy leaf lamina andgreen node.

: 3 hairy leaf lamina andpurplish node.

: 3 glabrous leaf lamina andgreen node.

: 1 glabrous leaf lamina andpurplish node.

small enough to weave through the thicket ofhairs to reach the epidermis. It is, neverthe-less, premature at this juncture to concludethat the resistance to aphid in this genotype isdue to the presence of hair, as the possibil i tyof antibiosis has not been established. Butthe potential of Serrano Tempiqueno as agood source of aphid resistance cannot beruled out. The present study indicated thatpubescence both in the internode and leaflamina can be transferred easily to glabroussusceptible types since both traits are con-ditioned by dominant genes that are closelylinked (5% recombination). Further investi-gation using isogenic l ines of SerranoTempiqueno differing only in thepubescence character may reveal the extentof resistance imparted by this charactertowards aphid in festat ion.

Examination of Table 7 indicates thatno hiHl individuals had been recovered fromthe F, populations in all the cross combina-tions studied. This is probably due to humanerror in phenotypic classification. Moreover,the population size studied was small and thenumber of individual expected of hiHl basedon the estimated 5% linkage is also verysmall. An alternative explanation is theinviabil ity of the hrHr individual which seemsto be rather unlikely.

Linkage studies show that pubescence

of internodes and leaf laminar is not

associated with the pigmentation of plantparts, except that internodal hair was foundto be very loosely l inked with nodal colourwith a recombination value of about 40percent.

Fruit colour (immature and mature)

The modes of inheritance of fruit

colour had been widely studied by a numberof workers. Oor-eNo (1948) studied severalcrosses involving immature fruit colour,

cedar green and sulphury white in four

American chil l i cultivars. He found 15:1

ratio for cedar green and sulphury white in

the F, populations and 3:1 in the backcrosspopulations. He concluded that two

recessive genes conditioned the expression

Similarly, the expected proportions ofphenotypes for joint F, segregation of i i).leaf laminar hair and internodal colour; i i i).internodal hair and nodal colour; iv). inter-nodal hair and internodal colour; v). inter-nodal hair and colour at petal base and vi).leaf laminar hair and colour at petal base, arepresented in Table 14. Most combinationsgive very good fit to an expected genetic ratioof 9:3:3:1 except one, v iz : in ternodal hai rand nodal colour, the fit was fairly poor.Linkage was therefore suspected and theest imated l inkase value was 39.2 : 4 ' ; .

DISCUSSION

Pubescence

Hairs have been considered as aprimitive manifestation in a number of plantspecies. It has certain adaptive advantagesover the glabrous form, particularly towardimparting resistance against certain pests.Presence of thick hair on stem and leaf acts asan effective physical barrier to a number ofsucking insects. This has been reported in thecase of cassava against the green spidermite( M onony chellus tanai o a ) (IITA, 1980).

The chill i cultivar from Mexico,Serrano Tempiqueno, has a thicket of hairson both the internodes and leaf laminae.Observations by the author indicate verymuch lower incidence of aphid infestation inthe plant house as well as in the field. How-ever, it was found to be equally susceptible tomite attack, probably because the mites are

r24

Table 14. Expected proportion of Fr phenotvpes and genetic tests on joint segregation ofstem/leaf pubescence and pigmentation on stem and petal base

r ) Leaf laminar hair versus nodal colour.

i i ) Leaf laminar hai r versus in ternodal co lour

th lcn 3h lcn I o ta t

6 1 1 6 3

3 . 9 1 1 . 8 6 3

P = 0 .7 -s -0 .90 a t 3 d . f

3h I c i t hlc i Toral

l 0 6 6 3

l l . 8 3 . 9 6 3

P : 0 .50-0 .7 ,5 a r 3 d . f

Expected F2

Observed No:

Expected.No:

Chi- square

Expected F2

Observed No:

Expected Ft

Observed No:

Expected F2

Observed No:

3Hlcn gHlcn

12 31

1 1 . 8

1 . 1 8 1 2

gHlci

36

9H'C'1 1

gHlcb

26

l o . +

3-5..1

3Hlci

l t

1 1 . 8

3Hlcn

1-5

1 2

3Hrcr

l-5

1 2

3Hlcb

10

8 . 8

3hrcn;+

1 2

3htcr

51 )

:nicb

3

8 .6

Expected No; 3-5.'l

Chi- square 1 .1012

i i i ) Internodal hair versus nodal colour.

Expected F, gHrcn

Observed No: 12

Expected No: 36

Chi-square 7.3331

I h lcn

3

I

P - 0.0,5

Total

64

6il

a r 3 d . f

iv ) In ternodal hai r versus in ternodal co lour

29 t2

I h ic i

2,1

P : 0 . 0 5 - 0 . 1 0

thicb

2

2 . 9

P 0 . 1 0 - 0 . 2 5

Total

,+6

16

a t 3 d . f .

Total

61

64

a r 3 d . f

Expected No: 36

Chi-square 6.833; l

v) Internodal hair versus petal base colour

qgicb 3Hicb

v i )

Expected No: 25.9 8.6

Chi-square 5.6413

Laminar hair versus petal base colour.

Expected F2

Observed No:

Expected No:

:n1Cb thlcb Total

7 4 4 ' . l

8 .8 2 .94 41

P : 0 .75-0 .90 a t 3 d . f .Chi-square 0.9802

t25

of sulphury whi te colour . This f ind ing wasfurther confirmed b1- JESWANI andDESPHANDE (19,56) in a cross between twogenotype having cedar green and let tuce oryel lowish green immature f ru i t co lour .

BaRntos and MosoreR (1972) a lso foundthat sulphury vellow \t! 'as recessive tog reen i sh ye l l ow . WEBBER ( 1912 ) andDespunNop, (1933) found that yellou'

immature f ru i t co lour was recessi re to € l reenbut was conditioned b.v a single gene.

Findings in this present stud"v-, how-

ever, indicate that the sulphury yellor,r 'immature f ru i t co lour of Ci l i Put ih Kelantanwas dominant over the green colour o1-Serrano Tempiqueno and Thai Yel low. andwas condi t ioned by two major genes. Thiscontradictory result is not unexpected asgenotvpes used in the studies were differentand phenotypic s imi lar i tv mav be a mani-festation of different genes. Therefore, thesulphury yellow character studied here in

fact can be controlled by different genes as

compared to the 'su lphury whi te ' o l

OnLRNo, 'yellowish green' of Jeswaxl.'green yellow' of B,cRRtos and 'yellow' of

WEBBER and DEsgP,qNoE.

HALSTED ( 191 1) in h is exper iment wi th'pepper', found only pale green fruit in the F ,hybrid derived from the cross between geno-

tvpes having pale green and ordinary green

immature fruit colour. He did not report on

the F, f ind ing. Based on h is F, data a lone,pale green can be regarded as dominant overordinary green. This is now confirmed by thepresent studies: the green colour fruit of Thai

Yellow and LIC 22was found to be dominant

over the dark green colour of Serrano

Tempiqueno and is conditioned by a single

factor.

The yellow matured fruit colour of Thar

Yellow and LIC 22 was found to be a single

recessive character. This finding is in agree-

ment with the findings of the earlier workers(Anoul RASHID KHAN and Muuauu.q'o

MUNIH 1954, EL Hessel and Sunu, 1970;

SOITAAUATHA PILLAI . GEORCN, ANdMERCY,

1977 ) .

In the l inkage studies, the immaturefruit colour of sulphury yellow of Cil i PutihKelantan and the dark green colour ofSerrano Tempiqueno is not associated withthe expression of the immature and maturefruit colour. This indicates that theexpression of the immature and mature fruitcolour is being controlled by separate andindependent processes.

Colour of plant parts (internode, node andpetal base)

The present studies indicate that thepurplish pigmentation on the internodes ofK5 is a monogenic dominant character overthe lack of pigmentation in SerranoTempiqueno. This is in agreement wi thearlier f indings of SouRNe.rsR et al.,(1977). HABIB and Mr,NstNrnr , (1971) a lsofound purple stem dominant over green butwas determined by three complementarygenes. No repor t on the inher i tance of purp lepigmentat ion on nodes has been noted. Thisstudv showed that purplish node is a mono-genic recessil 'e character. It is apparent thatp igmentat ion on in ternode and node is con-trolled by totally different alleles in separateloc i . L inkage studies has indicated that theyare located on different chromosomes.

There is also no report on the mode ofinheritance of colour pigmentation at thebase of petal. Present studies show that this

character is monogenic recessive. Linkageanalysis indicates that it segregated indepen-dently with respect to the internodal pigmen-

tation, but l inked quite closely with nodalpigmentation. The recombination value was

found to be approximately 8 percent.

Fruit type

The present studies have shown that

curved fruit tapered at the apex is a dominant

character over straight fruit rounded at the

apex. Visual observation also indicates that

curved fruit is very often associated with

taper-apex. Unfortunately data were not

available to provide evidence of l inkage.

126

a

ACKNOWLEDGEMENTS Science Branch and Encik Chan y ing Kwokfbr cr i t ica l lv going through the manuscr ipt .

The autnor would l ike to express h is Thanks are a lso due to Encik Sze Kok Wengappreciation to Encik Mohd. Senawi b. and Encik Zakaria b. Ghani for their assist-Dato ' Mohd. Tamin, former Head. Plant ance in carrv ins out th is t r ia l .

SUMMARY

The f indings of the modes of inher i tance for several morphological characters are best summarizedin Table 15. L inkages were onlv detected for the tb l lowing pairs of characters:-

1. Internodal and laminar hairs wi th about 5. i recombinat ion value.

2. Nodal and petal base pigmentat ion wi th 8.3.1 recombinat ion value.

3. Internodal hair and nodal p igmentat ion wi th 39.2.r recombinat ion ra lue.

Further studies are required to establ ish l inkage relat ionships between these morphologicalcharacters and the expression of pest /d isease resistance. This informatron is valuable for breeders as onceclose l inkages have been establ ished, the lengthv and of ten tedious disease/pest screening process can beel iminated. Select ion of resistant indiv iduals can then be based on the expression of the morphologicalcharacter known to be l inked c loselv wi th the pest or d isease under studv. This a lso al lou 's ear lv select ionof resistant types i f such morphological characters can be determined in the juveni le stages of the plants.

Tab le 15 . Summary tab le fo rmodeo f i nhe r i t anceo f somemorpho log i ca l cha rac te rsde te rm inedbv ear l ier workers and the Dresent author

Morphological Character Genetic Research Carried Out B!Rat io

1. Pubescence

i . Internodal hair 3: l Chew

i i . Leaf laminar hair 3: I Chew

2. Immature fruit colour

i . Cedargreen vs sulphury whi te 15: l Odland (19.18)

Cedar green vs yellowish green I 5: 1 Jeswani el a/ ( I 956)

Green vs yel low 3: l Webber ( l9 l2)Deshpande ( 1933)

Green vs sulphury yel low l :15 Chew

ii. Pale green vs ordinary green la Halsted ( l9l I )

Dark green vs green l:3 Chew

3. Mature fruit colour

i . Redvsye l l ow 3 :1 Abdu lR . Khane ta / ( 1954 )El Hassan el a/ ( 1 970)Somanatha Pillai et al (1977)Chew

4. Colour of plant parts

i . Purpl ishinternodevsgreen 3:1 SomanathaPi l la ieta l (1977\l b Hab ibe ra / (1971 )3 :1 Chew

ii. Purplish node vsgreen 1:3 Chew

iii. Purplish tinge at petal base vs white l:3 Chew

5. Fruit type

i. Straight vs curved 1:3 Chew

ii. Tapered vs rounded 3:1 Chew

la No F2 result w6 reported. All Fl plants w€re pale green

/b Three omplerentary genes were involved.

127

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