Interspecific hybridisation among vigna species

Interspecific hybridisation among vigna species- case study

1. Interspecific hybridisation among vigna species PRESENTED BY, S.DIVYA (2017600805)

2. What is Interspecific Hybridization ? Crossing between two different species of the same genus is referred to as Interspecific hybridization

3. Main features of interspecific hybridization It is used when the desirable characters not found within the species of a crop. It is an effective method of transferring desirable genes into cultivated plants from their related cultivated or wild species.

4. Why it is required in vigna species? Mung bean has desirable characters including erect growth habit, large number of seeds/pod, early maturity and desired quality traits. Urd bean has useful characters including synchronous maturity, non-shattering pods, bold seeds, more durable resistance to mung bean yellow mosaic virus . The desirable traits can be transferred from one species to another species by interspecific hybridization.

5. Potential sources of alien variation in vigna Resistance to bruchid Insect resistance YMV resistance V. riukinensis V. radiata var. sublobata V. umbellata V. nepalensis V. unguiculata ssp. dekindtiana var. pubescens V. radiata var. sublobata V. umbellata

6. Cont., Resistance to cowpea storage weevil Resistance to cowpea insects pests Resistance to yellow mosaic virus V. vexillata V. reticulata V. oblongifolia V. luteola V. vexillata V. radiata var. sublobata

7. Cont., Resistance to powdery mildew Resistance to pod bug V. stipulaceae V. reflexo – pilosa var. glabra V. unguiculata ssp. dekindtiana

8. Cont., High methionine content High photosynthetic efficiency and drought tolerance Drought tolerance Heat tolerance V. radiata var. sublobata V. radiata var. sublobata V. aconitifolia V. aconitifolia

9. Crossability studies in vigna species Most of the reports studying crossability among different Vigna species suggest that V. radiata produced successful hybrids as a female parent with V. mungo , V. umbellata , and V. angularis , while their reciprocal crossing was not successful

10. Crossability barriers in vigna species

11. CROSS INCOMPATIBITY The failure of male and female gametes to unite to form zygote in interspecific hybrids is known as CROSS INCOMPATIBILITY. CAUSES OF CROSS INCOMPATIBILITY Lack of pollen germination Insufficient growth of pollen tube to reach ovule Inability of the male gamete to unite with egg cell Known as pre-fertilization barriers

12. HYBRID INVIABILITY Inability of a hybrid zygote to grow into a normal embryo under the usual conditions of development is referred to as HYBRID INVIABILITY. CAUSES OF HYBRID INVIABILITY Unfavourable interaction between chromosomes of two species. Disharmony between cytoplasm and nuclear genes. Unfavourable interaction among embryo, endosperm and maternal tissues.

13. HYBRID STERILITY HYBRID STERILITY refers to the inability of a hybrid to produce viable offspring. CAUSE OF HYBRID STERILITY Lack of structural homology between the chromosomes of two species turn in to non-pairing or reduce pairing.

14. HYBRID BREAKDOWN When F1 plants of an interspecific cross are vigorous and fertile but their F2 progeny is week and sterile, it is known as HYBRID BREAKDOWN. CAUSES OF HYBRID BREAKDOWN Gene combination : Unfavourable combinations of dominant and recessive genes. Structural differences : Structural differences in the chromosomes.

15. Methods to overcome barriers in vigna species 1. Embryo rescue 2. Use of growth regulators 3. Use of bridge species 4. Reciprocal crosses 5. Chromosome doubling using colchicine treatment

16. Genetic transformation in Vigna species Crosses between mungbean and urdbean were attempted to combine desirable features such as durable resistance to MYMV and cercospora leaf spot, synchronous maturity, resistance to shattering and high methionine and more seeds per pod, erect growth habit

17. Some promising recombinants obtained from crosses between V. radiata × V. mungo

18. In the above traits, such as long pods, number of seeds per pod, and erect plant type may be transferred from mung bean, while increased no. of pod bearing and multiple clusters per peduncle may be transferred from urd bean into mung bean.

19. Some outstanding derivatives obtained from V. radiata × V. mungo crosses

20. CASE STUDY 1 Cross-compatibility of cultivated Adzuki Bean ( Vigna angularis ) and Rice Bean ( Vigna umbellata ) with their wild relatives

21. Cross-compatibility of cultivated Adzuki Bean ( Vigna angularis ) and Rice Bean ( Vigna umbellata ) with their wild relatives

22. RESULTS Siriwardhane et al., 1991 suggested that V. nakashimae and V. riukiuensis could be used as gene sources for the adzuki bean breeding programme though interspecific hybridization. Successful hybrids between adzuki bean and rice bean can not easily be produced. However, since V. riukiuensis is cross-compatible with both adzuki bean and rice bean , V. riukiuensis could be useful as a bridge species between adzuki bean and rice bean.

23. CASE STUDY 2 Interspecific hybridization of Vigna radiata x wild Vigna species for developing MYMV donar

24. The result of number of seed set and extent of germination in different interspecific crosses attempted are presented below

25. RESULTS In direct cross combinations, the highest pod set of 25 and crossability of 21.92 per cent were recorded by the cross V. radiata x V. radiata var. sublobata and lowest pod set of 2.0 per cent recorded by the cross V. radiata x V. dalzelliana .

26. CONCLUSION Vigna Species are important group of pulses and consisted of more than 200 species. Economic Vigna species are important source of legume protein for food supply. Crosses between species of same genera have contributed immensely to crop improvement. Thus ultimate goal of distant hybridization is to transfer useful genes from alien species into cultivated species. Among the Vigna species, Vigna radiata is genetically compatible with all other Vigna species as an female parent so it can be utilized as an bridge species in the interspecific hybridization programme. Crossability barriers during hybridization i.e. cross compatibility, hybrid inviability , hybrid sterility and its breakdown frustrate breeders’ efforts in successful hybridization between Vigna species. These barriers can be overcome through novel technologies. The interspecific hybridization in Vigna species can be useful in broadening of genetic base, bringing the characters like pod shattering, dormancy breakdown, biotic and abiotic resistance in cultivated economic Vigna species.

27. References Siriwardhane et al . (1991), Cross-Compatibility of cultivated Adzuki Bean ( Vigna angularis ) and Rice Bean (V. umbellata ) with their Wild Relatives, Plant Breeding 107, 320—325 Pandiyan et al. (2010) ,Interspecific hybridization of Vigna radiata x 13 wild Vigna species for developing MYMV donar , Electronic Journal of Plant Breeding, 1(4): 600-610