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United States Department of Agriculture (USDA) 2013

WIDENING THE GENETIC BASE OF US RICE GERMPLASM THROUGH INTROGRESSION OF NOVEL ABIOTIC STRESS TOLERANCE GENES FROM EXOTIC DONORS

Genetic Rice

United States Department of Agriculture (USDA) Research, Education & Economics Information System (REEIS)

Titre : WIDENING THE GENETIC BASE OF US RICE GERMPLASM THROUGH INTROGRESSION OF NOVEL ABIOTIC STRESS TOLERANCE GENES FROM EXOTIC DONORS

Identification : LAB04205

Pays : Etats Unis

Durée : Sep 1, 2013 à Aug 31, 2017

Domaine : qtl ; abiotic stress ; drought ; introgression lines ; marker assisted selection ; rice ; salinity

Partenaire : LOUISIANA STATE UNIVERSITY 202 HIMES HALL BATON ROUGE,LA 70803-0100

Objectifs
The overall goal of this proposal is to develop prebreeding lines with enhance abiotic stress tolerance and to dissect the genetic network associated with the complex abiotic stress tolerance mechanisms in rice using classical breeding, modern genomics, and physiological tools. This will be accomplished through the development and genetic characterization of several mapping populations developed from crosses involving known abiotic stress tolerant germplasm. Individual quantitative trait loci (QTL) will be studied for variation in abiotic stress tolerance within a nearly isogenic background. Our specific objectives are : To identify abiotic stress tolerance quantitative trait loci (QTLs) for marker-assisted selection in breeding program. To validate the identified QTLs in introgression line (IL) populations developed from abiotic stress tolerant donors in elite cultivar backgrounds. To fine map salt tolerance QTLs and select prebreeding lines with improved abiotic stress tolerance through marker-assisted pyramiding of beneficial QTLs.

Descriptif
Two recombinant inbred line (RIL) mapping populations will be developed from crosses involving elite US cultivars and abiotic stress (salinity and drought) tolerant donors. Both simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers will be used for linkage map construction and QTL analysis. Salt tolerance screening will be done at both seedling and reproductive stage following the procedures developed at the International Rice Research Institute. In addition to the standard evaluation score (SES) that is used to evaluate the symptoms of damage of salt injury, seedling height, root length, dry shoot weight, dry root weight, chlorophyll content, Na content, K content in root and shoot will be recorded. In case of salinity tolerance screening at the reproductive stage, observations will be recorded on plant yield and yield components, spikelet sterility, thousand grain weight, and chlorophyll content. Relative growth reduction from the measured parameters will be used for determining tolerance. Drought tolerance in mapping population will be evaluated in field and pot culture experiments. Observations will be taken on yield and yield related traits in both stress and control growing conditions. The physiological traits will include chlorophyll content, leaf water potential, membrane stability, relative water content, pollen viability, and spikelet sterility. In pot culture experiments, observations will be taken on root characteristics. A core set of introgression lines covering the whole genome of donors for salinity and drought tolerance will be developed in recurrent parental backgrounds and will be evaluated for abiotic stress tolerance. Observations will be recorded on traits as described above. If the difference in phenotypic values for the target traits between an introgression line and recurrent parent is statistically significant, QTL for salinity or drought tolerance will be assigned to the introgressed donor chromosome segment. The coincidence of the known salinity and drought tolerance genes with the QTL regions and consistency of the QTL discovered at both growth stages will be examined. All statistical analysis will be done using SAS procedures. For fine mapping of salt tolerance QTLs with large effects, large mapping populations will be developed using the ILs harboring the QTLs. Genotyping will be done to identify the recombinant individuals, which will be evaluated for salinity tolerance at both seedling and reproductive stages followed by progeny testing. Candidate genes will be identified from the fine mapped QTL region and their expression will be quantitated in both unstressed and stressed tissue samples of parents and selected ILs. The ILs harboring drought or salt tolerance QTLs will be selected and crossed to develop pyramided lines for evaluation of abiotic stress tolerance, plant characteristics, yield attributes, and grain quality. Important milestones in this project are salinity and drought tolerance QTL identification, IL development and evaluation, QTL validation, candidate gene identification, and development of prebreeding lines with favorable QTL combinations. These accomplishments will be disseminated to the intended audience through publications in refereed journals, presentations in professional meetings.

Présentation : USDA

Page publiée le 30 octobre 2015, mise à jour le 23 novembre 2017