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1. Resistant donors, Wild species and its role in pulse crop improvement By: Sunsitha.K Suriya.K

2. Introduction Pulses are an integral part of sustainable agriculture and human nutrition, providing essential protein, minerals, and vitamins,  However, the productivity of pulse crops such as is often hampered by several biotic and abiotic stresses. Diseases like fusarium wilt, ascochyta blight, and sterility mosaic virus, and pests such as pod borer and aphids cause significant yield losses. Likewise, environmental stresses like drought, salinity, and heat further reduce production potential. In this context, resistant donors and wild species play a critical role in developing improved pulse varieties that can withstand these challenges.

3. Importance of Genetic resistance Genetic resistance is  an inherent ability of an organism to reduce the likelihood of developing a specific disease , or to withstand environmental stressors, to its unique genetic makeup . The use of host plant resistance is one of the most economical, eco-friendly, and sustainable approaches for managing pests and diseases. Unlike chemical control measures, genetic resistance does not harm the environment or increase production costs. However, genetic resistance within cultivated species is often limited due to narrow genetic bases. Therefore, resistant donors and wild relatives serve as reservoirs of untapped genetic variation for resistance against biotic and abiotic stresses.

4. Wild Species and their role in crop improvement Wild species are the wild relatives of cultivated crops that have evolved naturally under various environmental conditions without human selection. They possess a wide range of  genetic diversity  and often harbour genes for  resistance to diseases, pests, and environmental stresses  that are absent in cultivated varieties. Utilising wild species in breeding programs has become an essential approach to enhance  crop yield, stability, and resilience  under changing climatic conditions.

5. Wild species in pulses and their applications S.no Wild species Major traits contributed Utility in crop improvement 1 Vigna mungo var silvestris ( Wild progenitor ) Strong resistance to YMV, Cercospora leaf spot, powdery mildew , drought tolerance, bruchid resistance Primary donor for major disease resistance genes; Development of CO 5, VBN (Bg) series. 2 Vigna trilobata Drought tolerance , root vigour ,tolerance to heat stress Exploited through hybridisation and recurrent selection for rainfed adaptation 3 Vigna mungo var glabra Tolerant to foliar diseases, improved pod traits Contributed to foliar disease tolerance in advanced selections; Source used in early screening procedures 1) Blackgram ( Vigna mungo)

6. 2.Green gram( Vigna radiata): Wild species Major traits contributed Utility in Crop improvement Vigna radiata var . sublobata ( wild progenitor) Resistance to MYMV, Powdery mildew and bruchid ; also confers drought tolerance Most widely used wild donor; Utilised in development of varieties CO 8, VBN(Gg) 3, VBN(Gg) 4,VBN (Gg) 5 Vigna radiata var . setulosa Early maturity and high seed protein ; Resistant to MYMV and Powdery mildew Genetic material used in resistant germplasm selection; donor for quality traits Vigna trilobata Drought and heat tolerance , earliness Used for improving dryland adaptability and early maturity lines like CO 6, and VBN(Gg)3 Vigna umbellata Bruchid resistance, improved pod wall strength and heat tolerance Evaluated as part of wild germplasm resources, for bruchid tolerance breeding.

7. 3.Red gram( Cajanus cajan): Wild species Major traits contributed Utility in Crop improvement Cajanus cajanifolius Source of A4 cytoplasm – major CGMS source Used for Hybrid development in CGMS system Cajanus scarabaeoides Resistant to pod borer, Sterility Mosaic Virus , Fusarium wilt and drought tolerance; Source of A2 cytoplasm Most widely used donor ; primary source of SMD and pod borer resistant genes. Development of CO ( Rg) 7, VBN (Rg) 3, and VBN (Rg)4. Used for CGMS source Cajanus acutifolius Resistance of Fusarium wilt , heat and moisture stress. Used in early hybrid and pure lines suited for dryland farming Cajanus platycarpus Strong resistance to pod borer, bruchid and leaf webber.Source of A7 cytoplasm . The accessions in germplasm maintenance use for resistance introgression Cajanus sericeus Resistance to Cercospora leaf spot , Alternaria blight and sterility mosaic. Source of A1 cytoplasm . Used for foliar disease resistance and protein enrichment

8. 4.Cowpea( Vigna unguiculata ): Wild species Major traits contributed Utilisation in Crop improvement Vigna unguiculata subsp . Dekindtiana ( wild progenitor ) Resistance to aphids , thrips , bruchid and bacterial blight; tolerant to drought and heat Used in the development of CO 5, VBN 3, and VBN 4 which show improved pest resistance Vigna vexillata Resistance to bruchids , pod borer and nematodes Used in wide hybridisation and pre breeding to transfer insect and abiotic stress resistance. Vigna luteola Tolerant to water logging, salinity and some foliar pathogens. Serves as donor for developing cowpea suitable for coastal and lowland conditions. Wild species Major traits contributed Utilisation in crop improvement Glycine soja Resistance to soybean rust , Cyst nematodes, drought and heat tolerance, high protein content Primary wild donor for disease and stress resistance. Used in MAS and hybridisation Glycine tomentolla Resistance to fungal pathogens, pod borer tolerance Donor of resistance genes for fungal disease and stress adaptation 5.Soybean( Glycine max):

9. Challenges in utilisation of Wild species Despite their potential, the use of wild species in breeding programs faces several challenges: Crossability barriers and hybrid sterility. Linkage drag ( undesirable traits transferred along with resistance genes). Limited availability of well characterised wild germplasm. Time-consuming and complex breeding process. Need for advanced biotechnological tools and expertise.

10. Resistant donors in Pulse breeding A resistant donor is a plant or genotype that possesses genes conferring resistance to a specific pest, disease, or environmental stress . These donors are used in breeding programs as parents to transfer resistance traits into high-yielding but susceptible cultivars through hybridisation and selection Resistant donors are identified through: * Screening germplasm collections under natural or artificial infestation. *Evaluation of genotypes in hotspot locations. * Use of molecular markers for identifying resistance-linked genes. These donors have been extensively used in breeding programs to develop improved cultivars suited for different agro-climatic zones. The most common sources of resistant donors for crop improvement are crop wild relatives, landraces, and germplasm collections

11. Major resistant donors in pulses Donor/accession Resistance/ Trait Application in Crop improvement Pant U-84; UPU-2  (cultivar/elite donor) Strong resistance to Mungbean Yellow Mosaic Virus (MYMV / YMD). Used as primary donor in crosses to transfer MYMV resistance; material used in inheritance studies and as source for mapping resistance. VBN series (VBN-4, VBN-6, VBN-7, VBN-8, VBN-11) Varieties/lines reported with field resistance/tolerance to YMV and adapted agronomic traits. Used as resistant parents for hybridisation, multi-location testing, TU 68 (advanced donor line) Bruchid (seed beetle) resistance reported in donor-derived crosses. Donor for introgressing post-harvest resistance into high-yielding cultivars via backcrossing and selection PU 31 Aphid tolerance Pest resistance donor 1. Blackgram

12. 2.Greengram Donor/ Variety/ Accesion Resistance/ Trait Utilisation in Crop improvement VBN (Gg) series – VBN 2, VBN 3, VBN 4 Resistant to Mungbean Yellow Mosaic Virus (MYMV) Used as donor parent for MYMV resistance in breeding and varietal development programs.( VBN 2 – parent of VBN 5 variety ) ADT 7 Resistant to MYMV Serves as resistant check and donor parent in hybridization programmes Pusa 105 Resistant to Powdery mildew Source of single gene-based powdery mildew resistance in breeding programs KU 301 Aphid tolerance Pest resistance

13. 3.Redgram Donor/ Variety / Accesion Resistance/ Trait Utilisation in Crop improvement Co(Rg) 7 Resistant to  Sterility Mosaic Disease (SMD)  and root rot Used as a donor parent in breeding for SMD and root disease resistance  VBN(Rg)3 Moderately resistant to SMD and tolerant to wilt Utilised in TNAU breeding programs to combine SMD and wilt tolerance with high yield and adaptability ICPL 87119 Resistant to Fusarium wilt and SMD Acts as a standard national donor for dual disease resistance; widely used in introgression breeding and gene pyramiding resistant to Fusarium wilt and SMD ICP 7035 Resistant to Fusarium wilt, SMD, and pod borer Highly used as a universal resistant donor ; parent for multiple resistant cultivars across India

14. 4.Cowpea Variety/ Accesion Resistance / Trait Utilisation in Crop Improvement VBN 1 Root rot tolerance Used as traditional check variety in development of VBN 3 TVu 6464 Aphids,Thrips resistant Used for developing new, more resilient cowpea varieties for food and fodder production .  Donor/ Accesion Resistance/ Trait Utilisation in Crop improvement JS 335 Virus resistance- Resistant to Yellow Mosaic Virus Development of JS 335 MACS 450 Resistant to Foliar disease like Powdery mildew Developing MACs 450 derived lines 5.Soybean

15. Methods of Utilisation of Wild species and Resistant donors in Crop improvement 1. Direct Selection and Evaluation:   Wild species or germplasm accessions are screened under field or controlled conditions for desirable traits such as resistance to diseases, pests, or environmental stress. Example:  Screening of  Vigna mungo var. silvestris  for resistance to mungbean yellow mosaic virus (MYMV). 2. Hybridisation (Interspecific and Intraspecific Crosses)  Crosses are made between cultivated varieties and resistant donors (wild or cultivated) to transfer desirable traits. Example: Cajanus scarabaeoides  ×  Cajanus cajan  to introduce sterility mosaic resistance in redgram . Vigna radiata var. sublobata  used for bruchid resistance in greengram .

16. 3.Backcross Breeding  After obtaining a hybrid between a cultivated and wild species, the hybrid is repeatedly backcrossed to the cultivated parent to recover the agronomic traits while retaining the resistance gene. Example:  Transfer of yellow mosaic virus resistance in blackgram through successive backcrosses with elite cultivars. 4.Embryo Rescue and Tissue Culture Techniques In wide crosses (cultivated × wild), embryos may abort due to incompatibility barriers. Embryo rescue and in vitro culture techniques help recover viable hybrids. Example:  Used in soybean and pigeonpea wide hybridization programs.

17. 5.Mutation Breeding Resistance donors can be developed artificially by inducing mutations in cultivated varieties using physical or chemical mutagens. Example:  MYMV-resistant blackgram mutant “Co 5” (TNAU). 6.Marker-Assisted Selection (MAS) and Genomic Approaches Molecular markers linked to resistance genes help identify and transfer desired traits precisely without linkage drag. Example:  Use of SSR and SNP markers in soybean for rust and root-knot nematode resistance. Other techniques include Somatic hybridisation, Genetic engineering and transgenic approach,Participatory varietal selection.

18. Conclusion Resistance donors and wild species are invaluable genetic resources for pulse crop improvement. They provide novel genes for resistance to pests , diseases and environmental stresses , contributing to the development of high-yielding , resilient and sustainable varieties. Through the integration of traditional breeding with modern genomic tools, the genetic diversity of pulses can be effectively broadened.