Genetica (1973) 44:264-269

S T U D I E S ON T H E I N T E R S P E C I F I C H Y B R I D S OF

T R I G O N E L L A C O R N I C U L A T A L., T. H A M O S A L. AND

T. C R E T I C A L.

AVTAR SINGH

Department of Genetics, Punjab Agricultural University

Ludhiana, India

Received April Io, i972 ] Accepted January 25, 1973

Chromosome associations in the interspecific hybrids of Trigonella corniculata, T. hamosa and T. cretica have been studied. T. hamosa differs from T. corniculata and T, cretica by one translocation. No translocation was detected in the hybrid T. corniculata × T. cretica. These species have basically the same genomes.

Introduction

Trigonella /oenum-graecum L. and T. corniculata L, are crops of

economic importance in India, Crosses between these two and other

species viz. T. hamosa L., T. cretica L. and T. coerulea L. were under-

taken with a view to transferring characters from one species to

another and s tudying the interrelationships. T. [oenum-graecum and

T. coerulea could not be crossed as male or female parents with any

other species. Several hundred crosses of T. ]oenurn-graecum made

with other species for two successive years failed. 7". corniculata,

however, hybridized with T. hamosa and T. cretica. Crosses between the latter two species were also successful. The meiotic behaviour of the F1 hybrids and its significance are reported in this paper.

Material and Methods

Seeds of T. corniculata were obtained from the Hort icul ture Depar tment of the Punjab Agricultural Universi ty and those of T. hamosa and T. cretica from the Plant Int roduct ion Division,

Indian Agricultural Research Inst i tute, New Delhi. Crosses were

made from 9 a.m. to 1 1 a.m. in the field. The F1 hybrids were grown along with the parents in pots. Young inflorescences were fixed

I N T E R S P E C I F I C HYB R IDS OF T R I G O N E L L A 265

between 9 a.m. and 10 a.m. in acetic-alcohol (1:2) containing ferric chloride. Anthers were squashed in acetocarmine and the pollen mother cells were studied and photographed on temporary slides. Pollen fertility was determined by staining with acetocarmine. Leaves were photographed on pressed specimens.

Observations

T. hamosa X T. corniculata and T. corniculata x T. cretiea hybrids had slightly pointed leaflets unlike the parents whereas T. hamosa X

T. cretica hybrids had leaves like those of the hamosa parent (Fig. 1). All three parental species showed n = 8 and formed bivalents.

Chromosomal associations in F1 hybrids at diakinesis and metaphase I are given in Tables 1 and 2.

7'. hamosa X T. corniculata: Eight bivalents were formed in 52.17% of the cells at diakinesis and 78.05% of cells at metaphase I. Up to one quadrivalent and two univalents were also seen in some cells (Figs. 2 and 3). Cells with univalents were more frequent at metaphase I (19.51%) than at diakinesis (8.68%).

T. hamosa X T. cretica: Pollen mother cells in this hybrid showed stickiness (Fig. 4) and only 10 ce]ls at diakinesis and 30 at metaphase I could be studied. Eight bivalents at metaphase I were observed in 86.66% of the cells. This hybrid also showed up to one quadrivalent and two univalents in some cells.

T A B L E 1

CHROMOSOMAL ASSOCIATIONS AT DIAKINESIS IN Ft HYBRIDS TRIGONELLA HAMOSA x T. CORNICULATA AND T. HAMOSA x T. CRETICA

Cross No. of U n i v a l e n t s B iva l en t s Quadr iva l en t s

cells per cell per cell per cell

s tud ied R a n g e Mean R a n g e Mean R a n g e Mean

T. hamosa

X

T . corniculata

T. hamosa

x

T. cretica

92 0 -2 0.174 5 -8 7.087 0- I 0,413

I0 -- -- 6-8 7.20 0-I 0.40

TA

BL

E

2

tO

0",

0",

CH

RO

MO

SOM

AL

ASS

OC

IAT

ION

S A

T M

ET

APH

ASE

I I

N T

RIG

ON

EL

LA

CO

RN

ICU

LA

TA

, T

. H

AM

OSA

AN

D T

. C

RE

TIC

A A

ND

TH

EIR

F~

HY

BR

IDS

Par

ents

an

d

No.

of

Un

ival

ents

]3

ival

ents

per

cel

l Q

uad

riv

alen

ts

Ch

iasm

ata

l~ol

len

Fi

hy

bri

ds

cell

s p

er c

ell

Rin

g

Ro

d

per

cel

l p

er c

ell

fert

ilit

y

stu

die

d

Ran

ge

Mea

n

Ran

ge

Mea

n

Ran

ge

Mea

n

Ran

ge

Mea

n

Ran

ge

Mea

n

(%)

T.

cor~

dcul

ata

30

--

--

5--8

6.

20

1-3

1.80

T.

ha

mo

sa

30

--

- 5

-7

6.50

1-

3 1.

50

T.

cret

ica

30

--

--

4

-7

6.33

1-

4 1.

67

T.

ha

mo

sa

×

T.

corn

icu

lata

41

0

-2

0.39

2

-6

4.07

2

-6

3.68

T.

ha

mo

sa

×

T.

cret

ica

30

0-2

0.

20

2-6

4.

03

2-5

3.

80

T.

cret

ica

>(

T,

ha

mo

sa

55

0-4

0.

836

2-7

4

.29

l-

5

3.11

T,

corn

icu

lata

×

T.

cret

ica

60

0-2

0.

40

3-6

4.

45

2-5

3.

35

_ m

m

13-1

6 14

.3

I0.6

5

94.7

2

13-1

6 14

.53:

k0.1

5 9

2.7

3

12-1

5 14

.33:

k0.1

41

93.9

9

0-1

0.02

4 9

-14

I

1.90

:k0.

146

59.9

1

0-1

0.03

3 9

-14

11

.97:

k0.2

27

74.2

8

0-1

0.09

0 9

-15

11

.94

~0

.22

8

63.1

4

10

-14

1

2.2

7±

0.1

18

8

8.2

1

< ~0

I N T E R S P E C I F I C HYBRIDS OF TRIGONELLA 267

268 AVTAR SINGH

T. cretica x T. hamosa: Eight bivalents were formed in 52.72% of the cells at metaphase I. Up to one quadrivalent (Fig. 5) and four univalents were observed in some cells of this hybrid. Pollen fertility ranged from 50 to 76% in different plants.

T. corniculata x T. cretica: At metaphase I, 80% of the cells had eight bivalents and no quadrivalent was observed. However, two univalents at metaphase I were observed in some cells (Fig. 6). This hybrid showed stickiness with occasional laggards at anaphase I (Fig. 7). Chiasma frequency and pollen fertility were highest of all hybrids studied.

Anaphase I was found to be normal in all hybrids except in T. cor-

niculata x T. cretica where it showed stickiness. No meiotic irregu- larity beyond anaphase I was found. There was good seed-set in all the hybrids.

Discussion

Tables 1 and 2 reveal that T. hamosa differs from T. corniculata and T. craica by one translocation. The rarity of quadrivalents in the pollen mother cells of the hybrids may be due to small segments involved in translocation as suggested by KHUSH (1962) in inter- specific hybrids of Secale. The hybrid T. corniculata x T. cretica

which formed only bivalents and occasionally univalents showed no multivalent. This suggests that their complements have not differentiated by a detectable translocation.

Disharmonious genic function in the hybrids is exhibited by stickiness of chromosomes at meiosis. HERMSEN & RAMANNA (1969) also observed sticky clumps in the hybrid Solanum acaule x S. bul-

bocastanum. Stickiness was observed in the hybrid of T. hamosa X T.

Figs. 1-7. Trigonella species and hybrids . Fig. 1: Leaves, upper row, left : T. corniculata; middle : T. hamosa; r ight : T. cretlca; lower row, left : T. hamosa

× T. corniculata; middle: T. cretica × hamosa; r ight : T. corniculata × T.

cretica. Figs. 2-7: Meiosis in hybr ids 1200 X : (2-3) :F. hamosa X corniculata,

with l iv(arrow) + 61i, and 7ix + 21, respect ively; - (4) T. hamosa X T. cretica,

metaphase I; - (5) T. cretica x T. hamosa, metaphase I wi th l iv(arrow) + 6ii; - (6-7) T. corniculata X T. cretica, metaphase I wi th 711 + 2I(arrows) and

anaphase wi th laggard, respectively.

INT E R S P E C IF IC H Y B R I D S OF TRIGONELLA 269

cretica whereas its reciprocal cross was normal in this respect. THOMP- SON (1930) has attributed reciprocal differences to peculiar interactions between the genes of one parent and the cytoplasm of the other.

The hybrid T. corniculata × T. cretica showed high pollen fertility (88.21%) which indicates comparatively less divergence of the chromosome sets of the two species. High pollen fertility in the interspecific hybrids Linum corymbi/erum × L. usitatissimum (89.2%) and L. a/ricanum × L. decumbens (93%) where all chromosomes paired as bivalents, was observed by GILL & YERMANOS (1967).

On the basis of chromosomal associations at meiosis and pollen and seed fertility of the hybrids it nlay be suggested that the genomes of T. hamosa, T. corniculata and T. cretica are highly homologous and basically the same. The three species of Trigonella studied here are naturally self-pollinating as the flowers open only after the dehiscence of their anthers at the bud stage. The self-pollinating nature of these species is the major barrier for the exchange between their genic pools. Speciation in Trigonella has been mainly brought about by structural changes and mutations as pointed out by SINGH & ROY (1970).

T h a n k s are due to Dr. J. L. MINOCHA for his in te res t in th is work.

REFERENCES

GILL, K. S. & D. M. YERMANOS (1967). Cytogenic s tudies on the genus Linum. I. H y b r i d s a m o n g t a x a wi th 15 as t he haploid c h r o m o s o m e n u m b e r . Crop Sci. 7 : 623-631.

HERMSEN, J. G. T. H. • IV]. S. ]~AMANNA (1969). Meiosis in different F1 hybr ids of Solarium acaule Bit t and S. bulbocastanum Dun. and i ts bear ing on genome re la t ionship , fer t i l i ty and breeding behaviour . Euphytica 18 : 27-35.

KHUSH, G. S. (1962). Cytogene t ic and evo lu t iona ry s tud ies in Secale. II. In te r -

re la t ionsh ips of the wild species. Evolution 16: 484-496.

SINGH, A. & R. P. ROY (1970). Karyologica l s tud ies in Trigonella, Indigo]era and Phaseolus. Nucleus 13: 41-54.

THOMPSON, \V. P. (1930). Causes of differences in success of reciprocal in ter-

specific crosses. Am. Naturalist 6 4 : 4 0 7 419.