Development of a molecular marker for a bruchid (Callosobruchus chinensis L.) resistance gene in mungbean

Abstract

Bruchid, Callosobruchus spp. (Coleoptera: Bruchidae), is a serious pest during storage of seeds of mungbean (Vigna radiata (L.) Wilczek) and other Vigna species. A source of resistance to this pest has been identified in Vigna sublobata (Roxb.) Bairig. accession TC1966. Two hundred recombinant inbred lines at the F(12) generation have been developed for molecular mapping of bruchid resistance (Br) gene in TC1966. Through bulked segregant analysis (BSA), ten randomly amplified polymorphic DNA (RAPD) markers associated with the bruchid resistance gene were successfully identified. A total of four closely linked RAPDs were cloned and transformed into sequence characterized amplified region (SCAR) and cleaved amplified polymorphism (CAP) markers. Seven CAPs developed from the identified RAPD markers showed tighter linkage with the Br gene than the original RAPD. Through transformation of RAPDs into CAPs, codominant markers for bruchid resistance were successfully obtained. Homozygous genotypes of these PCR-based markers were estimated to contribute 85% of the variance for seed damage when the insect assay was performed under favorable growth conditions for bruchid

Breeding Food Legumes for Resistance to Storage Insect Pests: Potential and Limitations

“…It is likely that prices of agrochemicals in general and chemical insecticides in particular will rather rise in the future as the reserves of non-renewable raw materials are dwindling and the world is currently facing unprecedented economic crises [18]. The storage structures in use under small-scale production conditions of the Tropics and Sub-tropics are not suitable for the use of chemical insecticides especially for formulations like fumigants [15]. In most cases, the storage structures are built within the same houses the families dwell and this makes the use of chemical insecticides more hazardous to human health.…”

“…In most cases, the storage structures are built within the same houses the families dwell and this makes the use of chemical insecticides more hazardous to human health. Since seed lots used for consumption and planting are kept in the same granaries, the use of chemical insecticides as a means of controlling storage insects is not advisable [15,19]. Furthermore, the prevalence of large stocks of sub-standard and poor quality insecticides in a number of developing countries further aggravates the problem.…”

“…The higher the levels of these components for a given trait, the higher will be the genetic gain expected from each cycle of selection. In many legumes, different sources of resistance to storage insect pests have been identified from cultivated varieties, germplasm collections and species of wild relatives [10,15,16,22,24].…”

“…While genes for complete resistance to insect pests in general and storage insects in particular are of rare occurrence in nature for cultivated species [25], they have often been reported in species of wild relatives for a number of legume crops [10,[15][16][17]24,26]. Nevertheless, a few cases of complete resistance were also reported in cultivated or germplasm collections of haricot bean [26][27][28], field pea [29,30], cowpea [31][32][33], black gram [34] and chickpea [13,35].…”

“…An effective and environment-friendly management option against storage insect pest in different legume crops could be achieved by improving the genetic resistance of the host plant [10,[13][14][15][16][17]. Nevertheless, most of the breeding programs pursued hitherto focus more on improving seed yield and quality than improving resistance against storage insect pests.…”