RSCS 2006

Crossability barriers in mungbean (Vigna radiata L. Wilczek): with its wild relatives A. Bharathi, K. S.Vijay Selvaraj, P. Veerabadhiran and B. Subba Lakshmi Tamil Nadu Agricultural University, Coimbatore-3, India Abstract Wide hybridization enables the interspecific gene transfer, which may lead to the additional source of variation for the desirable characters. The present study was carried out to study the crossability relationship of seven cultivars of Vigna radiata (L) with six V. umbellata accessions, five V. aconitifolia accessions V. trilobata, and V. sublobata . It revealed that there was no free crossing in these species, pod set percentage and pods harvested varied with combinations of two parental cultivars of each species for most of the interspecific hybrids. In the present study, successful pod set was observed on 60 crosses out of 65 interspecific crosses with V.radiata as ovule parent, it was observed the crossability was higher in V. radiata X V. umbellata crosses Viz CO 6 X LRB 296 (29.63%), CO 6X LRB 297 (18.64%). Moderate crossability was observed in V. radiata Var. CO 4 X V. trilobata (8.48%) and V. radiata Var. CoGg 917X V. aconitifolia (7.69%) crosses of V. radiata cultivars with V. sublobata and V. aconitifolia showed poor pod set percentage. Few accessions of V. aconitifolia and V.umbellata showed poor pod set when crosses between V. umbellata and V. radiata revealed the least number of pod set (0.005%) with poor filling of seeds which were shriveled. This may be due to embryos abortion and degeneration during embryogenesis.

Key words:

Interspecific hybridization, Vigna species.

Introduction Grain legumes are important sources of dietary protein in Asia, Africa, and Latin America. Vigna species, particularly the mungbean (Vigna radiata (L.)Wilczek, 2n=22) are widely cultivated in Asia. The yield of mungbean is stagnant over years because of the narrow genetic variability in the primary gene pools, the limited gene pool of the cultivated species of Vigna has restricted the conventional plant breeding programme to improve the yield. For producing the crop types, which combine the high productivity quality, and resistance to disease and pest, it has become necessary to widen the gene pools of the cultivated species through interspecific hybridization. This would be enabling the interspecific gene transfer, which may lead to the additional sources of variation for the desirable characters (Stalker, 1980). Besides the cultivated species of Vigna the wild species are Vigna trilobata, Vigna grandis, Vigna

CIENCE

THE ROYAL

YO CIET F CR

S OP

Indian J. Crop Science, 1(1-2): 120-124 (2006)

SO

A. Bharathi et al.

Crossability barriers in mungbean dalzalliana, Vigna vexillata, Vigna radiata sublobata, and Vigna mungo Var. silvestris.

Var.

Varying degrees of success in interspecific hybridization of Vigna have been reported (Chen et al., 1977; Chowdhury and Chowdhury, 1977; Ahn and Hartmann, 1977, 1978). The causes of failures of interspecific crosses in food legumes are not fully understood. in some case, the pollen tubes are unable to penetrate the stigma and style (Chowdhary and Chowdhury, 1977). in other cases, fertilization occurs, but embryo abortion takes place during embryogenesis (Honma,1956 and Al-Yasiri,1966). The failure of interspecific hybridization due to embryo degeneration is common in interspecific crosses of food legumes (Ahn and Hartmann,1977 and Chen et al.,1977). More over interspecific hybrids obtained are often completely sterile or only partial fertile, while relatively few are fertile. This investigation reports the effects of parental cultivars on interspecific hybridization, crossability barriers and their reasons. Materials and methods During the kharif 2005, experimental crossing plots were raised at Tamil Nadu Agricultural University, Coimbatore, India. The Vigna and wild relatives were planted separately for crossing (Table 1). Anthers were carefully removed from female parent before the day interspecific crossing and properly bagged with butter paper cover to avoid selfing and unnecessary crosses. Crossing has done in morning hours 6 am to 9 am, which is the ideal anthesis time for Vigna sp. Observations were recorded viz. number of flowers crossed, number of pod set, pod set percentage and number of viable seeds per pod. Based on these quantitative observation results were interpreted and discussed below. Result and Discussion The crossability of Vigna radiata x Vigna sublobata, Vigna radiata x Vigna trilobata, Vigna radiata x Vigna umbellata and Vigna radiata x Vigna aconitifolia was successful only. Vigna radiata was used as the female parent. Differences in percentage of pods harvested were highly significant among the crosses and between the two cultivars of V.radiata (Table 2)

Crossability barriers in mungbean [ 121 ] Table 1: List of parents used for interspecific hybridization Female parent

Male parents

Vigna radiata var CoGg 912

Vigna sublobata

Vigna radiata var CoGg 917

Vigna trilobata

Vigna radiata var VBN 2

Vigna umbellata

Vigna radiata var Co 4

LRB 297

Vigna radiata var Co 4

LRB 282 LRB 296 LRB 111 LRB 287 Rice bean local Vigna aconitifolia GMO 9703 GMO 9704 RMO 60 RMO 257 Moth bean local

The best combination was Vigna radiata x Vigna umbellata (CO 6 x LRB and CO 6x LRB 297) records highest pod set percentage viz. 29.63% and 18.64 %. There was no significant difference between the cultivars of pollen parent for the number of pods harvested as well as between the use of cultivars and intraspecific hybrids as parent for the species cross. The set-pods developed normally to maturity. There was no significant difference in number of seeds per pod among the different combinations of parental cultivars. For the reciprocal cross, early pod development appeared normal, but subsequently aborted. No viable seeds were obtained for this cross. The relatively high number of pods harvested for Vigna radiata x Vigna umbellata (CO 6 x LRB 296 and CO 6 x LRB 297) suggested there were no barriers in crossing of these two species for the parental cultivars used. However, there were barrier in embryogenesis as produced inviable and viable seeds. But completely inviable seeds in all reciprocal crosses. The reciprocal difference in crossability between Vigna radiata and Vigna sublobata, Vigna trilobata, Vigna umbellata and Vigna aconitifolia suggests interaction between genic and cytoplasmic factors (Stebbins, 1958). This

interaction may be the cause of hybrid embryo degeneration when Vigna mungo is used as the female parent (Ahn and Hartmann, 1977). There are no external barriers, which prevent cross-pollination between Vigna radiata and Vigna sublobata, and Vigna radiata x Vigna trilobata, because the timing of anthesis, dehiscence of anthers and receptivity of the stigma are identical for both the parental species. Normal pollen germination in both selfed and cross flowers shows that the stigma does not act as barrier. Absence of seed set and abscission of crossed flowers within four days from pollination in crosses Vigna radiata x Vigna umbellata (CoGg 917 x Rice bean local, Co4 x LRB 297 and Co 4 x LRB 111) and Vigna radiata x Vigna aconitifolia (CoGg 917 x RMO 60, CoGg 917 x RMO 257 and VBN 2 x GMO 9703) demonstrate that the first barrier responsible for complete sterility is the delay in pollen tube entry in to the ovules. This might be expected because of the difference in the length of style of three species (23 mm long in Vigna radiata, 19mm long in Vigna umbellata and 13 mm long in Vigna aconitifolia). Such barriers are known in many other interspecific crosses also (Maheswari and Rangaswamy, 1965). Pre fertilization barriers are absent in the interspecific crosses Vigna umbellata x Vigna radiata, Vigna sublobata x Vigna radiata and Vigna trilobata x Vigna radiata reciprocal crosses as evident from normal pollen tube growth in both selfed and crossed flowers and low abscission rate of crosses flower within 72 hours from pollination. How ever, the high rate of abscission of young fruits between 3 to 30 days after pollination and low seed set are suggestive for the presence of post fertilization barriers. The failure of endosperm nuclei to divide or the delayed endosperm nuclear divisions are responsible abortion of embryo and the subsequent abscission of young fruits in the interspecific crosses: the production of shriveled seeds from these crosses is probably associated with the failure of embryo to reach maturity. These crossability barriers between the cultigen and its wild relative constitute somatoplastic sterility (Mayo, 1980). Such sterility barriers have been recorded in the interspecific crosses between Phaseolus lunatus x Phaseolus vulgaris (Mok et al., 1979). These different kinds of pre and post fertilization barriers are also responsible for complete sterility to low fertility in the back crosses involving the F1 hybrid and both its parents.

Indian J. Crop Science 1, 1-2 (2006)

[ 122 ]

A. Bharathi et al.

Table : 2 Crossability barriers in Vigna radiate (Vigna radiata (L.)Wilczek. 2n=22) with wild relatives. No.

Crosses

Number of flower crossed

Number of pod set

Percentage of pod set

No of Seeds / Pod Mean

Range

Remarks

1

V. radiata var CoGg 912 x V. sublobata

215

15

7.4

3.5

0-7

Tiny. shrivelled seeds

2

V.radiata var CoGg 912 x V. trilobata

213

10

4.67

4.5

0-9

'

V. radiata x V. umbellata

Viable seeds. Good

3

CoGg 912 x LRB 297

95

10

11.57

6.5

1-13

'

4

CoGg 912 x LRB 282

65

10

15.38

3.3

3-9

'

5

CoGg 912 x 296

46

5

12.76

4.5

1-10

'

6

CoGg 912 x LRB 111

47

5

10.63

2

0-4

'

7

CoGg 912 x LRB 287

76

8

11.84

2

0-4

'

8

CoGg 912 x Rice bean local

195

19

9.74

2.3

3-7

' Viable seeds. Good

V. radiata x V. aconitifolia 9

CoGg 912 xGMO 9703

69

5

7.34

2.2

2-5

'

10

CoGg 912 x GMO 9704

59

2

3.38

2.5

6-11

'

11

CoGg 912 x RMO 60

64

7

10.93

5.5

4-15

'

12

CoGg 912 x RMO 257

58

3

5.17

3.5

2-9

'

13

CoGg 912 x Moth bean local

184

11

5.97

2.5

2-7

'

14

V. radiata var CoGg 917 x V. sublobata

170

7

4.11

1.6

1-4

Tiny. shrivelled seeds

15

V. radiata var CoGg 917 x V. trilobata

182

14

7.69

3

0-6

' Viable seeds. Good

V. radiata x V.umbellata 16

CoGg 917 x LRB 297

72

7

9.72

1.8

1-4

'

17

CoGg 917 x LRB 282

73

4

5.47

2.5

1-6

'

18

CoGg 917 x 296

64

4

6.25

1.5

0-3

'

19

CoGg 917 x LRB 111

68

3

4.41

1.5

0-3

'

20

CoGg 917 x LRB 287

58

4

6.89

2.5

0-5

'

21

CoGg 917 x Rice bean local

188

16

8.51

2

1-5

' Viable seeds. Good

V. radiata x V. aconitifolia 22

CoGg 917 xGMO 9703

72

1

1.38

0

0

'

23

CoGg 917 x GMO 9704

70

3

4.28

3

1-7

'

24

CoGg 917 x RMO 60

67

0

0

0

0

'

25

CoGg 917 x RMO 257

53

0

0

0

0

'

26

CoGg 917 x Moth bean local

170

12

7.05

2.5

2-7

'

27

V. radiata var VBN 2 x V. sublobata

190

8

4.21

1.2

1-5

Tiny. shrivelled seeds

28

V. radiata var VBN 2 x V. trilobata

162

7

10

2

0-4

' Viable seeds. Good

V. radiata x V. umbellata 29

VBN 2 x LRB 297

70

7

10

2

0-4

'

30

VBN 2 x LRB 282

61

8

13.1

1.5

0-3

'

31

VBN 2 x 296

65

5

7.69

2

0-4

'

Indian J. Crop Science 1, 1-2 (2006)

Crossability barriers in mungbean [ 123 ] 32

VBN 2 x LRB 111

56

4

7.12

2

0-4

'

34

VBN 2 x LRB 287

44

4

7.12

2

0-4

'

35

VBN 2 x Rice bean local

157

15

9.55

1.5

0-4

' Viable seeds. Good

V. radiata x V. aconitifolia 36

VBN 2 xGMO 9703

60

0

0

0

0

'

37

VBN 2 x GMO 9704

53

3

5.66

1.5

1-4

'

38

VBN 2 x RMO 60

56

2

1.78

4.4

0-4

'

39

VBN 2 x RMO 257

55

2

3.63

3

2-4

'

40

VBN 2 x Moth bean local

196

13

6.63

4.5

2-9

'

41

V. radiata var Co 4 x V. sublobata

237

18

7.59

3.5

0-7

Tiny. shrivelled seeds

42

V. radiata var Co 4 x V. trilobata

224

19

8.48

3

2-8

' Viable seeds. Good

V. radiata x V. Umbellata 43

Co 4 x LRB 297

85

0

0

0

0

'

44

Co 4 x LRB 282

81

4

4.94

3

3-6

'

45

Co 4 x 296

91

2

1.09

3

0-6

'

46

Co 4 x LRB 111

72

0

0

0

0

'

47

Co 4 x LRB 287

77

5

6.49

2

2-6

'

48

Co 4 x Rice bean local

203

14

6.9

3

V. radiata x V. aconitifolia

' 0-6

Viable seeds. Good

49

Co 4 xGMO 9703

29

1

2

1.36

2

'

50

Co 4 x GMO 9704

64

0

0

0

0

'

51

Co 4 x RMO 60

64

2

3.12

2

2-4

'

52

Co 4 x RMO 257

77

0

0

0

0

'

53

Co 4 x Moth bean local

153

19

12.42

4.5

2-11

'

54

V. radiata var Co 6 x V. sublobata

218

7

3.21

6.5

3-14

Tiny. shrivelled seeds

55

V. radiata var Co 6 x V. trilobata

214

13

6.05

2

5-9

' Viable seeds. Good

V. radiata x V. umbellata 56

Co 6 x LRB 297

59

11

18.64

5.5

1-11

'

57

Co 6 x LRB 282

97

7

7.5

3

3-6

'

58

Co 6 x 296

54

16

29.63

1.5

4-7

'

59

Co 6 x LRB 111

71

5

7.04

3.5

1-7

'

60

Co 6 x LRB 287

84

13

15.48

2.5

4-9

'

61

Co 6 x Rice bean local

181

12

6.63

3

3-9

' Viable seeds. Good

V. radiata x V. aconitifolia 62

Co 6 xGMO 9703

98

5

5.1

3

0-6

'

63

Co 6 x GMO 9704

55

3

5.45

2.5

2-7

'

64

Co 6 x RMO 60

60

3

6.67

2

0-4

'

65

Co 6 x RMO 257

79

3

5.06

4.5

3-12

'

66

Co 6 x Moth bean local

183

8

4.37

3.5

2-9

'

Indian J. Crop Science 1, 1-2 (2006)

[ 124 ]

A. Bharathi et al.

References Ahn C.S and Hartmann R. W. 1977. Interspecific hybridization among four species of the genus Vigna. In: proc.First Intl. Mungbean Symposium. Asian vegetable Research and Development Centre. Shanhua. Taiwan: pp 240-246 Ahn

C.S and Hartmann R.W. 1978. Interspecific hybridization between mungbean Vigna radiata L.. Wilczek. and adzuki bean Vigna angularis Wild. Ohwi andOhashi. J. Amer. Soc. Hort.Sci., 103:3-6.

Chen. N.C., Parrot J.F, Jacobs T., Baker L.R. and Carlson P.S. 1977. Interspecific hybridization of food legumes by unconventional methods of plant breeding. in Proc. First Intl. Mungbean Symposium: Asian Vegetable Research and Development Centre. Shanhnua. Taiwan. pp 247-252. Chowdhury R.K. and Chowdhury J.B. 1977. Intergeneric hybridization between Vigna mungo L.. Hepper and

Indian J. Crop Science 1, 1-2 (2006)

Phaseolus calcaratus RoxB. 117-121.

Indian J. Agric. Sci., 47:

Dana.S. 1967. Hybrid from the cross Pheseolus aureus RoxB X P.calcaratus RoxB., J. Cytology and Genet., 2:92-97. Maheswari P. and Rangaswamy N.S. 1965. Embryology in relation to physiological and Genetics: Advances in botanical research. Vol.2 pp 219-312. Academic Press. London. Mayo O. 1980. Theory of Plant Breeding. Clarendon press. Oxford. Mok D.W.S., Mok M.C. and Rabakorihanta A. 1979. Fertilization and early embryo development in reciprocal interspecific crosses of Phaseolus. Theor.Appl. Genet., 57: 59-65. Stebbins G.L 1958. The in viability. weakness. and sterility of interspecific hybrids. Adv.Genet,. 9: 147-215.