Molecular Markers for Biomass Traits: Association, Interaction and Genetic Divergence in SilkwormBombyx mori

Abstract

Improvement of high yielding, disease resistant silkworm strains became imminent to increase production of silk, which is a major revenue earner for sericulturists. Since environment interacts with phenotype, conventional breeding did not result in commendable yield improvement in synthetic strains of silkworm, Bombyx mori. Identification of DNA markers associated with different economically important biomass traits and its introgression could assist molecular breeding and expression of stabilized high yielding characters, but genetic basis of most quantitative traits in silkworm is poorly understood due to its polygenic control. Correlation analysis (R = 0.9) revealed significant interrelation among biomass traits viz., larval duration (TLD), larval weight (LWT), cocoon weight (CWT), shell weight (SWT), shell ratio (SR) and floss content. PCR using inter simple sequence repeat (ISSR) primers revealed 92% polymorphism among 14 tropical and temperate strains of B. mori, with average diversity index of 0.747. Stepwise multiple regression analysis (MRA) selected 35 ISSR markers positively or negatively correlated with different biomass traits, illustrated polygenic control. ISSR marker 830.81050bp was significantly associated with LWT, CWT, SWT, SR and floss content, indicated its pleiotropic role. Two ISSR markers, 835.51950bp and 825.9710bp showed significant association with floss content and TLD. These markers were segregated in F2 generation and Chi-square test confirmed (χ2 = ~45; P < 0.05) its genetic contribution to the associated biomass traits. Strains, with both positively and negatively correlated markers, had intermediate mean value for biomass traits (eg. SWT = 0.17 ± 0.014 g in GNM and Moria) indicated interaction of loci in natural populations. Low yielding Indian strains grouped together by Hierarchical clustering. Chinese and Japanese strains were distributed in the periphery of ALSCAL matrix indicated convergence of genetic characters in Indian strains. Average genetic distance between Chinese strains and Indian strains (0.193) significantly (P < 0.01) varied from that between Chinese and Japanese strains. Interaction of loci and allelic substitutions induced phenotypic plasticity in temperate B. mori populations on tropic adaptation in India. These outcomes show possibility to combine favorable alleles at different QTL to increase larval, cocoon and shell weight.

Assessment the Protective Role of Quercetin on Acrylamide-Induced Oxidative Stress in Rats

“…The present results indicated that depletion of GSH in ACR received group, which may be partially responsible for the increased lipid peroxidation agreement (Pradeep et al . ).…”

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene

“…The observed values of Tajima's D and Fu's F S neutrality tests were -1.83527 (p < 0.05) and -15.020 (p = 0.000), respectively. 819, with Hemiptera (Abbot 2001;Taylor et al 2011); UBC-836, UBC-840, UBC-856 and UBC-880 with Hymenoptera (Borba et al 2005;Nascimento 2008); and the primers UBC-809, UBC-810, UBC-812, UBC-818, UBC-836, UBC-840 and UBC-886 were reported for Lepidoptera (Kar et al 2005;Pradeep et al 2007;Velu et al 2008).…”

Identification of ISSR markers associated with valerenic acid content and antioxidant activity in Valeriana jatamansi Jones in the West Himalaya

“…Bocianowskia and Katarzyna (2012) studied the relationships between randomly amplified polymorphic DNA (RAPD) markers and 22 quantitative traits of caraway (Carum carvi L.) using regression analysis and found 44 RAPD markers to be associated with at least one trait. Similarly, several markers which have been identified to be associated with valerenic acid content and antioxidant activity were found to show an interactive effect of selected independent variables on the dependent variable (Steel and Torrie 1980;Pradeep et al 2007). Multigenic control of the valerenic acid content or antioxidant activity traits has also been substantiated (Shibukawa et al 1986).…”