QTL mapping for leaf rust resistance in bread wheat using PBW343/W8627 RIL population.

Area of Science:

• Plant Breeding and Genetics
• Agronomy
• Molecular Biology

Background:

• Leaf rust, caused by *Puccinia triticina*, significantly reduces bread wheat yields (10-50%) due to evolving virulent pathotypes that overcome existing resistance genes.
• Developing durable resistance is crucial for sustainable wheat production, necessitating the identification of novel genetic loci conferring resistance.

Purpose of the Study:

• To map quantitative trait loci (QTLs) associated with leaf rust resistance in bread wheat at both seedling and adult plant stages.
• To identify potential candidate genes for leaf rust resistance and their utility in breeding programs.

Main Methods:

• A recombinant inbred line (RIL) population derived from a cross between PBW343 and W8627 was evaluated for leaf rust resistance over two crop seasons.
• Genotyping of the RIL population was performed using 3.9K DArT SNPs for QTL mapping.
• In silico analysis was conducted to identify putative candidate genes associated with mapped QTLs.

Main Results:

• Significant differences in leaf rust resistance were observed among RILs across different years.
• Two QTLs for all-stage resistance (*QLr.iiwbr.2B.1* on chromosome 2B and *QLr.iiwbr.5B.1* on chromosome 5B) and one QTL for adult plant resistance (*QLr.iiwbr.6B.1* on chromosome 6B) were identified.
• A putative candidate gene encoding Annexin (*TraesCS5B02G201700*) was identified through in silico analysis, implicated in wheat disease resistance.

Conclusions:

• The study successfully identified novel QTLs conferring resistance to wheat leaf rust, providing valuable genetic resources for breeding programs.
• Further characterization of these QTLs and the candidate Annexin gene will enhance their application in developing durable rust-resistant wheat varieties.