Location: Sunflower Improvement Research
Project Number: 3060-21220-034-017-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2019
End Date: Dec 31, 2024
Objective:
1. Identify, transfer and validate white mold (WM) resistance factors from P. coccineus and P. vulgaris in common bean breeding lines.
2. Define meta-QTL for resistance to white mold in common bean and verify their phenotypic effect.
3. Define physical regions of the common bean genome associated with major white mold resistance QTL and investigate candidate genes.
4. Genotype WM-MAGIC population with GBS/SNPs and phenotype for white mold reaction.
Approach:
Objective 1: Lines developed from inbred backcross populations from P. vulgaris //P. vulgaris x P. coccineus crosses will be used to identify QTL associated with WM resistance. Those QTL will be validated in separate populations and environments to determine if they are broadly expressed in multiple populations. Nested Association Mapping will be used to further characterize QTL found in P. coccineus derived breeding lines. New sources of resistance in P. vulgaris identified in the Snap Bean Diversity Panel (SBDP) through GWAS have been crossed to susceptible lines to create recombinant inbred (RI) populations to characterize potentially novel QTL for resistance.
Objective 2: Effect of major QTL alone or in combination with other known QTL will be elucidated. FY19-20 efforts will focus on completing the development of two RIL populations PT9-5-6/USPT-WM-12 (~150 lines) and PT12-37/VCP-13 (~150 lines), screening them in the greenhouse straw test, and increasing seed of them for field trials in 2020. Advanced dry bean lines from these populations with improved resistance to white mold will be entered into the Bean White Mold Nursery (BWMN) conducted by Steadman.
Objective 3: High molecular weight DNA will be isolated, and the lines will be sequenced to 8x coverage using Illumina Hi-Seq 2500 technology. The reads will be mapped to the reference genome, and the tolerant and susceptible lines will be compared to discover regions in which a high number of fixed SNPs are located. Those regions with excess number of fixed SNPs will represent the introgressed QTL. The WM5.4 QTL will be positioned relative to the position of the indel markers used for the traditional QTL analysis, and the region that overlaps between the sequencing and QTL analysis will be considered the region to search for candidate genes.
Objective 4: A MAGIC (Multi-parent Advanced Generation Inter-Cross) population obtained from crosses among eight parents representing diverse sources of white mold resistance will provide a) a high resolution mapping population that will augment the GWAS analysis; and b) a new source of germplasm for future cultivar development and variety release.
