Screening Strains of the Mulberry Silkworm, Bombyx mori, for Thermotolerance

A tropical climate prevails in most of the sericultural areas in India, where temperature increases during the summer lead to adverse effects on temperate bivoltine silkworm rearing and cause crop losses. Screening for thermotolerance in the silkworm, Bombyxmori L. (Lepidoptera: Bombycidae) is an essential prerequisite for the development of thermotolerant breeds/hybrids. In the current study, the aim was to identify potential bivoltine silkworm strains specific for tolerance to high temperature. The third day of fifth stage silkworm larvae of bivoltine strains were subjected to high temperature of 36 ± 1° C with RH of 50 ± 5 % for six hours (10:00–16:00) every day until spinning for three consecutive generations. Highly significant differences were found among all genetic traits of bivoltine silkworm strains in the treated groups. Three groups of silkworm resulted including susceptible, moderately tolerant, and tolerant by utilizing pupation rate or survival rate with thermal stress as the index for thermotolerance. Furthermore, based on the overall silkworm rearing performance of nine quantitative genetic traits such as larval weight, cocoon yield by number and weight, pupation, single cocoon and shell weight, shell ratio, filament length and denier, three bivoltine silkworm strains, BD2-S, SOF-BR and BO2 were developed as having the potential for thermotolerance. The data from the present study enhance knowledge for the development of thermo tolerant silkworm breeds/ hybrids and their effective commercial utilization in the sericulture industry

MaizeGDB: curation and outreach go hand-in-hand

First released in 1991 with the name MaizeDB, the Maize Genetics and Genomics Database, now MaizeGDB, celebrates its 20th anniversary this year. MaizeGDB has transitioned from a focus on comprehensive curation of the literature, genetic maps and stocks to a paradigm that accommodates the recent release of a reference maize genome sequence, multiple diverse maize genomes and sequence-based gene expression data sets. The MaizeGDB Team is relatively small, and relies heavily on the research community to provide data, nomenclature standards and most importantly, to recommend future directions, priorities and strategies. Key aspects of MaizeGDB's intimate interaction with the community are the co-location of curators with maize research groups in multiple locations across the USA as well as coordination with MaizeGDB’s close partner, the Maize Genetics Cooperation—Stock Center. In this report, we describe how the MaizeGDB Team currently interacts with the maize research community and our plan for future interactions that will support updates to the functional and structural annotation of the B73 reference genome

Distinct Genetic Architectures for Male and Female Inflorescence Traits of Maize

We compared the genetic architecture of thirteen maize morphological traits in a large population of recombinant inbred lines. Four traits from the male inflorescence (tassel) and three traits from the female inflorescence (ear) were measured and studied using linkage and genome-wide association analyses and compared to three flowering and three leaf traits previously studied in the same population. Inflorescence loci have larger effects than flowering and leaf loci, and ear effects are larger than tassel effects. Ear trait models also have lower predictive ability than tassel, flowering, or leaf trait models. Pleiotropic loci were identified that control elongation of ear and tassel, consistent with their common developmental origin. For these pleiotropic loci, the ear effects are larger than tassel effects even though the same causal polymorphisms are likely involved. This implies that the observed differences in genetic architecture are not due to distinct features of the underlying polymorphisms. Our results support the hypothesis that genetic architecture is a function of trait stability over evolutionary time, since the traits that changed most during the relatively recent domestication of maize have the largest effects

Towards molecular breeding of reproductive traits in cereal crops

The transition from vegetative to reproductive phase, flowering per se, floral organ development, panicle structure and morphology, meiosis, pollination and fertilization, cytoplasmic male sterility (CMS) and fertility restoration, and grain development are the main reproductive traits. Unlocking their genetic insights will enable plant breeders to manipulate these traits in cereal germplasm enhancement. Multiple genes or quantitative trait loci (QTLs) affecting flowering (phase transition, photoperiod and vernalization, flowering per se), panicle morphology and grain development have been cloned, and gene expression research has provided new information about the nature of complex genetic networks involved in the expression of these traits. Molecular biology is also facilitating the identification of diverse CMS sources in hybrid breeding. Few Rf (fertility restorer) genes have been cloned in maize, rice and sorghum. DNA markers are now used to assess the genetic purity of hybrids and their parental lines, and to pyramid Rf or tms (thermosensitive male sterility) genes in rice. Transgene(s) can be used to create de novo CMS trait in cereals. The understanding of reproductive biology facilitated by functional genomics will allow a better manipulation of genes by crop breeders and their potential use across species through genetic transformation

Genetics of Maize Inflorescence Architecture

150 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.Maize inflorescences have become a model system for functional genomics from agronomic, developmental, and evolutionary viewpoints. The purpose of this research was to gain deeper insights into genetic control of quantitative variation for maize inflorescence architecture. Two biparental populations with different genetic backgrounds and mating structures were used to identify the locations and effects of quantitative trait loci (QTL) influencing the different components of maize inflorescences. A comprehensive set of maize inflorescence architecture traits were measured in multiple replicates and environments. The use of the intermated B73 x Mo17 (IBM) population revealed a relatively large number of significant QTL for all the inflorescence traits. Tassel architecture showed strong modular development, with traits integrating into modules that are consistent with different orders of meristems involved in tassel development. The central spike of the tassel and kernel row number showed strong positive correlation and also explained most of the common variation between the tassel and ear. Novel methodology was developed for detecting QTL with pleiotropic effects on inflorescence traits that integrated or showed high correlations. The maize nested association mapping (NAM) panel, a tremendous genetic resource developed for genome-wide high-resolution mapping, was used to more precisely understand the genetic architecture of tassel traits. This resource will help considerably to identify the genes underlying the QTL controlling inflorescence architecture. We propose a few candidate genes that underlie inflorescence architecture QTL in all three studies on the basis of positional information and functional relevance. The overall findings indicate that the majority of variation in inflorescence architecture is controlled by many genes, mostly with small effects, and their identity is mostly still unknown. The NAM strategy appears to be a promising tool for high resolution mapping and discovery of candidate genes controlling the development of maize inflorescences.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD