CEBR2-08

Mapping QTLs For Traits Linked To Heat Tolerance Genes During Grain Filling in Spring Wheat

Researchers

Dr. Mohamed N. R. Barakat

Dr. Abdullah A. A. AL-Doss

Dr. Khaled A. A. Moustafa

ABSTRACT:

Environmental stresses such as heat, cold, drought, and high salinity influence plant growth and productivity of wheat (Triticum aestivum L.). Post-anthesis high temperature stress in wheat is a major cause of yield reduction in some regions in Saudi Arabia. Understanding the genetic basis of the tolerance to high temperature is important for improving the productivity of new spring wheat cultivars developed for the regions where the stress occurs. This project aims to understand the genetic basis of heat tolerance by mapping quantitative trait loci (QTL) linked to heat tolerant genes to identify and describe and localize quantitative trait locus (QTL) alleles for the improvement heat tolerant in new wheat populations.

The project includes two methods:

The first method will attempt to identify and map quantitative trait loci (QTL) linked to heat tolerance in F2 populations. For this purpose, the F2 populations will be developed from a cross between heat tolerant parents (such as KSU 106 from Saudi Arabia, Danbata from Nigeria or Debra from Sudan) and heat–sensitive (Yecora Rojo). Wheat germplasms (parents and F2 populations) will be screened under stress and non-stress conditions to identify heat tolerant wheat lines during grain filling. The populations will be characterized for agronomic traits including grain filling duration (GFD), kernels per spike (KS), thousand kernel weight (TKW), grain filling rate (GFR) and grain yield(GY). Molecular markers, mainly Random amplified polymorphic DNA (RAPD), Inter-simple Sequence repeat polymorphic DNA (ISSR), Sequence characterized amplified region (SCAR), Microsatellites (SSR) and a Sequence tag site (STS) will be used to construct a linkage map and will be mapped using Mapmaker software.

The second method will attempt to detect and transfer valuable QTLs alleles of heat tolerance from an unadapted wheat germplasm into adapted cultivar (Yecora Rojo) using advanced backcross QTL strategy and microsatellite markers. DNA fragments of specific marker for heat tolerance will be sequenced. Original and known collected sequences of the tolerant genes will be aligned using ClustalX 1.64 with default options.

OBJECTIVES:

The main objectives of the project can be summarized as follows:

  1. To identify RAPD, ISSR, STS and SSR markers linked to heat tolerance genes using bulked segregate analysis in F2 population. The RAPD and ISSR makers will be transformed to SCAR markers, which is more useful for practical breeding purpose.
  2. To determine the contribution of the mapped QTL to variation in heat tolerance genes in an F2 population.
  3. Characterization and mapping QTL linked to high – temperature tolerance genes under controlled temperature using SSR and STS markers and to establish a relationship between loci that are linked to yield – related traits under high temperature.
  4. Detecting and transferring valuable QTLS alleles of heat tolerance from unadapted wheat germplasm into elite cultivar using advanced backcross QTL strategy and microsatellite markers.