Authors: Nangsol dolma bhutia , Boniface Lepcha
Genetic Improvement of Vegetable Crops Utilizing Crop Wild Relatives
The Crops Wild Relatives (CWR) includes wild forms, Progenitors and those species that are closely related to cultivated crops. These are the reservoir of Variation which provide raw material for the breeder. In the recent past the importance of CWR have been recognized globally for breeding high yielding varieties to feed the increasing population and to breed varieties that are tolerant to stresses arising due to climate change. The increasing genetic uniformity of crop varieties combined with climate change effects makes crops more vulnerable to various biotic and abiotic stresses. Crops Wild Relatives are therefore important for maintaining genetic diversity for and preventing losses as a result of genetic uniformity (eg-potato famine in Ireland) which may have serious consequences for food, nutrition and environmental security.
Despite having valuable genes with immense value for crops improvement and adaptation to changing environment conditions, utilization of CWR has enjoyed a great success only in few crops. In potato, use of Solanum demissum provided resistance to late blight while in tomato more than 40 resistance genes have been derived fromS.peruvianum, S.pennellii Correl var.pennelli, Lycopersicon cheesmanii, L.pimpenefolium for traits such as increased soluble solid content, fruit colour, against tomato leaf curl virus and Late blight (Rick and Chetelat).Using genes obtained from wild Italian Brassica oleracea, varieties with high levels of anti-cancer compounds have been developed in Broccoli.The species of Solanum complex such as S.incanum, S.viarum, S.melongena var.insanum, S.khasianum have provided gene for resistance to Fusarium wilt, bacterial wilt, frost tolerance and fruit & shoot borer. The wild species of Okra Abelmoschus tuberculatus to Yellow vein mosaic virus and wild cucumbers Cucumis hardwickii and C.callous have resistance to downy mildew and fruit fly, Cucumis melo var. chito for Fusarium wilt resistance.
Wild species/species complexes that have studied and utilized are few considering the large number of native economically important taxa.To cope with problems arising from intensive modern agriculture and climate change, it is essential to maintain genetic diversity within crop gene pools. In the past crop breeders had been struggling with the problem of linkage drag while dealing with CWR. Nevertheless, now the advances in DNA sequencing technology particularly combination of de novo sequencing and resequencing are being used efficiently to explore useful genetic variation in CWR. Therefore, plant breeders have to work closely with genetic engineers to develop new cultivars. There is need to design altogether new crops, plant types and varieties, which have the ability to perform well under adversities. Nature does not produce individual plants resistant to all stresses and neither can the breeder. It is natural genetic diversity, in which many individuals, each somewhat different genetically, thrive together, allows a population to withstand challenges to its survival and produce traits of needs.
About Author / Additional Info:
Indian Agricultural Research Institute