Location: Dale Bumpers National Rice Research Center
Project Number: 6028-21000-012-018-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jul 1, 2024
End Date: Jun 30, 2028
Objective:
The main object of this research is to develop climate-resilient varieties that are high yielding and have good grain quality. The researchers also aim to understand the impact high temperatures have on yield and grain quality, phenotypic plasticity, genetic basis for heat tolerance and their interactions. High temperatures during grain-filling have been shown to reduce photosynthetic efficiency, grain yield, cooking quality and sensory quality, and increased grain chalkiness. The specific objectives are to: (1) phenotype a 400 line Heat- Multi-parent Advanced Generation Inter-Cross (MAGIC) population at flowering and grain-filling under high temperatures in the field and greenhouse; (2) conduct genome-wide association analysis to identify genetic regions associated with good yield and grain quality; (3) characterize physiology of haplotypes carrying favorable loci for improved tolerance to heat stress; and (4) perform transcriptome analysis of selected Heat-MAGIC lines and to develop SNP assays for high temperature resilience loci.
Approach:
(1) To identify high temperature tolerant lines, (a) 250 Heat- Multi-parent Advanced Generation Inter-Cross (MAGIC) lines will be evaluated in two locations in the US, Stuttgart, and Mississippi, under field conditions. There will be two treatments, a control (regular planting) and a late planting (about early June) to experience air temperatures greater than 34 0C . 400 Heat-MAGIC lines will be evaluated in two locations, Philippines, and India, under field conditions. Additionally, the 400 Heat-MAGIC lines will be evaluated under greenhouse conditions at IRRI under control and high temperature. Standard agronomic data as well as canopy temperature and stomatal conductance will be collected. (b) Grain size, iron and zinc content of each plot will be determined, and a heat susceptibility index will be determined.
(2) To identify genetic regions associated with high temperature tolerance during the flowering and grain-filling (a) phenotypic data collected from all evaluations will be used for genome-wide association analysis. A mixed model approach will be used for each individual environment and combined environments for each treatment condition, control, and high temperature. (b) A set of 20 lines with contrasting haplotypes will be selected for transcriptome analysis for yield and nutritional quality. (c) Plausible candidate genes of detected genetic loci will be identified by in silico analysis of gene functions and querying rice gene networks.
(3) To develop a high temperature SNP assay (a) RNA will be extracted and sequenced, and transcriptomes will be analyzed, and interaction networks developed. (b) High temperature validated SNPs with the best contrasting alleles will be added to IRRI’s exiting breeding SNP chip. (c) Release high temperature Heat-MAGIC lines for use in US rice breeding programs.
