WILD RELATIVES OF CROP PLANTS IN INDIA: ISSUES AND PRIORITIES

WILD RELATIVES OF CROP PLANTS IN INDIA: ISSUES AND PRIORITIES

Dr. E. Roshini Nayar
Principal Scientist,
National Bureau of Plant Genetic Resources,
New Delhi 110012

Indian region is one of twelve megacentres of diversity for crop plants. Based on the number of species available in the region, their characters vis-à-vis crop plants, distribution patterns and areas/ habitats of build-up of diversity the Indian region has been designated as a primary centre of diversity of several crops such as rice, black gram, jute, and a wide regional centre of diversity for green gram, wheat, Citrus. It is also a secondary centre of diversity of several crops namely Carthamus, Crotalaria and Corchorus. Importance of wild species of crop taxa, in the wake of technological advances in study and utilization of species as a source of germplasm for pre-breeding and genetic enhancement of crops for specific traits, have made these a priority for exploration and collection, exchange and conservation. At the same time, post-CBD (Convention on Biological Diversity), concerns of habitat loss and genetic erosion have resulted in emphasis on in-situ conservation; problems of access and benefitsharing and sovereign rights and other policy issues too have come to the forefront. The issues and priorities in this important group of agro-diversity are highlighted.

Selected wild species of crop taxa have been a priority for collection and screening for their potential importance. Oryza nivara, in Vigna, sublobata-silvestris types related to green and black gram, Abelmoschus tuberculatus, in Solanum, insanum-incanum types closest to brinjal, have been the focus for collection and crossability studies in India and elsewhere. Endemic species, related to the crop taxa have been the focus for representation of diversity in the gene-bank, which include Cajanus cajanifolia, species closest to pigeon pea and found in the Eastern Ghats, Vigna khandalensis endemic to Western Ghats and others. Among the priority species, of over 115 species (more than 2500 accessions) collected, nearly 90 species (more than 1100 accessions) had been conserved (analysis done upto 2005).

Taxonomic and biosystematic studies have focused on crop groups, represented by a large number of species in the Indian region. Studies in Vigna have focused on crossability studies to establish relationships and estimate distances between the cultivated and wild types of V. umbellata (rice bean), V. radiata-V. mungo (green gram and black gram), delineating the diagnostic characters among morphologically similar species of the Asiatic Vigna group (subgenus Ceratotropis) and molecular characterization of distinct variants among these. Macrotyloma has similarly been the focus of study on a morphological and molecular basis for delineating species closest to the crop (Macrotyloma uniflorum, horse gram) and relationship with newly collected and described species M. sar-garhwalensis, as also the Solanum melongena complex of species. Citrus is another taxon, which was initially thought to be a recalcitrant species but was experimentally proven to be orthodox; C. indica, the species native to parts of the north eastern region, has been the focus for collection and study in recent programmes.

Crotalaria, a large genus with a secondary centre of diversity in India, was studied from the point of view of diversity distribution of species closest to the crop species. In Allium, represented by several crop and locally useful economic species, all species have been collected except for three species which could not even be located in their type localities; a key to the identification of species was developed.

The focus in wild relatives of crop plants as a genetic resource thus requires consolidation and analysis of information on taxonomy, distribution, reproductive behaviour vis-à-vis their population structure, strategies for conservation of seeds and populations, the genetics of resistance to abiotic and biotic stresses and the potential for use in crop breeding programmes. Herbarium-based and experimental studies are therefore needed on this group to identify areas of diversity, alternative conservation strategies, including in-situ conservation. Species/ species complexes that have been studied are few considering the large number of native economically important taxa in India. Species introduced for their potential importance are another large resource which needs to be conserved on a priority basis as future introductions are likely to be few especially since these are now exchanged only with prior consent and under material transfer and benefit- sharing agreements.