A review of the implications of heterozygosity and inbreeding on germplasm biodiversity and its conservation in the silkworm, Bombyx mori
1Central Sericultural Germplasm Resources Centre, Central Silk Board, Thally Road, Hosur, Tamil Nadu-635 109,
India
2Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan-115, ROC.
Abstract
Silkworm genebanks assume paramount importance as the reservoirs of biodiversity and source of alleles that can be easily retrieved for genetic enhancement of popular breeds. More than 4000 Bombyx mori L (Lepidoptera: Bombycidae) strains are currently available and these strains are maintained through continuous sibling mating. This repeated sibling mating makes the populations of each strain more homozygous, but leads to loss of unique and valuable genes through the process of inbreeding depression. Hence, it is essential to maintain a minimal degree of heterozygosity within the population of each silkworm strain, especially in the traditional geographic strains, to avoid such loss. As a result, accurate estimation of genetic diversity is becoming more important in silkworm genetic resources conservation. Application of molecular markers help estimate genetic diversity much more accurately than that of morphological traits. Since a minimal amount of heterozygosity in each silkworm strain is essential for better conservation by avoiding inbreeding depression, this article overviews both theoretical and practical importance of heterozygosity together with impacts of inbreeding depression and the merits and demerits of neutral molecular markers for measurements of both heterozygosity and inbreeding depression in the silkworm Bombyx mori.
Keywords: conservation, genetic diversity, inbreeding depression, molecular markers
Abbreviations: HFC, heterozygosity fitness correlations; ID, inbreeding depression; SNP, single nucleotide polymorphisms; SSR, microsatellites
Correspondence: a*anujnh@yahoo.co.in, bkvijayan01@yahoo.com, cdrpsunder@rediffmail.com, dbabu_jica@yahoo.co.in, edirector_csgrc@yahoo.com. *Corresponding author
Editor: Brad Coates was editor of this paper.
Received: 31 October 2009 | Accepted: 26 March 2010 | Published: 26 January 2011
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 11, Number 8
Jingade AH, Vijayan K, Somasundaram P, Srinivasababu GK, Kamble CK. 2011. A review of the implications of heterozygosity and inbreeding on germplasm biodiversity and its conservation in the silkworm, Bombyx mori. Journal of Insect Science 11:8 available online: insectscience.org/11.8