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Showing papers by "Amit Singh published in 2002"


Journal ArticleDOI
TL;DR: Repeat unit length and restriction site variation in ribosomal RNA gene clusters (rDNA) was surveyed in 77 Arachis accessions and found that some SacI, BamHI and TaqI cleavage sites in rDNA unit were highly conserved.
Abstract: Repeat unit length and restriction site variation in ribosomal RNA geneclusters (rDNA) was surveyed in 77 Arachis accessions, includingsamples from 39 accessions of cultivated Arachis hypogaea(2n=4x=40), 36 accessions representing 15 related tetraploid and diploidwild species, and two synthetic amphidiploids. Total genomic DNA wasdigested with five restriction enzymes, and probed with three heterologousribosomal clones of wheat and broad bean. Four rDNA repeat unit lengthclasses were recognized in the Arachis species. Restriction site analysisshowed that some SacI, BamHI and TaqI cleavage sites in rDNA unit werehighly conserved. With few exceptions, the variable BamHI and EcoRV siteswere able to differentiate the taxonomic sections and species, respectively.Arachis hypogaea and A. duranensis accessions produced fourrDNA length classes. Among these, three were identical with those of otherArachis species. A SacI restriction site (s) from probe (Ver6-5) cangenerally distinguish the two subspecies A. hypogaea ssp. hypogaea and A. hypogaea ssp. fastigiata. Forty nine per centof bands were polymorphic across the A. hypogaea accessionsanalysed. This study does not support A. batizocoi to be a progenitorof A. hypogaea. For the gene array, the contribution from eachparental genome can be detected in the two synthetic amphidiploids.

17 citations


Journal ArticleDOI
TL;DR: The inhibitory activity of ent-norsecurinine alkaloid was evaluated against spore germination of some plant pathogenic fungi and Curvularia maculans, C. species, and C. palliscens were the most sensitive as complete inhibition of spore Germination was observed at 1000 ppm.
Abstract: Increased agricultural production is attributed to excessive use of synthetic chemicals during the last century. This has raised a number of ecological and human health problems as most of them are associated with several harmful effects, e.g., prolonged existence of these chemicals in the environment leads to resurgence of resistance among various fungi, and contaminates environment and food chain, which cause serious ecological imbalance. Increasing awareness of possible deleterious effects of fungicides on the ecosystem and growing interest in pesticide-free agricultural products have led to diversion of attention towards environment friendly approaches, such as genetic engineering for evolving resistant varieties and use of induced

14 citations