Understanding the genetic basis of spike fertility to improve grain number, harvest index, and grain yield in wheat under high temperature stress environments

Authors: PRADHAN, SUMIT - University Of Florida; BABAR, MD ALI - University Of Florida; ROBBINS, KELLY - Cornell University; Bai, Guihua; MASON, RICHARD - University Of Arkansas; KHAN, JAHANGIR - University Of Florida; SHAHI, DIPENDRA - University Of Florida; AVCI, MUHSIN - University Of Florida; GUO, JIA - University Of Florida; HOSSAIN, MOHAMMAD - University Of Florida; BHATTA, MADHAV - University Of Florida; MERGOUM, MOHAMED - University Of Georgia; ASSENG, SENTHOLD - University Of Florida; St Amand, Paul; GEZAN, SALVADOR - University Of Florida; Baik, Byung-Kee; BLOUNT, ANN - University Of Florida; Bernardo, Amy

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2019
Publication Date: 11/29/2019
Citation: Pradhan, S., Babar, M., Robbins, K., Bai, G., Mason, R., Khan, J., Shahi, D., Avci, M., Guo, J., Hossain, M., Bhatta, M., Mergoum, M., Asseng, S., St. Amand, P.C., Gezan, S., Baik, B.V., Blount, A., Bernardo, A.E. 2019. Understanding the genetic basis of spike fertility to improve grain number, harvest index, and grain yield in wheat under high temperature stress environments. Frontiers in Plant Science. 10. Article 1481. https://doi.org/10.3389/fpls.2019.01481.
DOI: https://doi.org/10.3389/fpls.2019.01481

Interpretive Summary: Heat stress during the post-flowering stage can cause substantial yield losses in most US wheat-growing areas. Increasing spike fertility (SF) and improving the partitioning of carbohydrate assimilates can improve wheat yield potential under heat stress environments. We conducted a genome-wide association study on 236 soft wheat elite lines that were tested for yield traits in two heat stress locations over three years. We identified DNA markers for eight yield-related traits. Heat stress tolerance genes detected on chromosomes 1B, 3A, 3B, and 5A could be used in marker-assisted breeding for improving wheat grain yield under post-flowering heat stress conditions.

Technical Abstract: Moderate heat stress accompanied by short episodes of extreme heat during the post anthesis stage is common in most US wheat growing areas and causes substantial yield losses. Sink strength (grain number) is a key yield limiting factor in modern wheat varieties. Increasing spike fertility (SF) and improving the partitioning of assimilates can optimize sink strength which is essential to improve wheat yield potential under a hot and humid environment. A genome-wide association study (GWAS) allows identification of novel quantitative trait loci (QTLs) associated with SF and other partitioning traits that can assist in marker assisted breeding. In this study, GWAS was performed on a soft wheat association mapping panel (SWAMP) comprised of 236 elite lines using 27,466 single nucleotide polymorphisms (SNPs). The panel was phenotyped in two heat stress locations over three years. GWAS identified 103 significant marker-trait associations (MTAs) (p = 9.99 x 10-5) related to eight phenotypic traits including SF (a major component of grain number) and spike harvest index (SHI, a major component of grain weight). MTAs detected on chromosomes 1B, 3A, 3B, and 5A were associated with multiple traits and are potentially important targets for selection. More than half of the significant MTAs (60 out of 109) were found in genes encoding different types of proteins related to metabolism, disease, and abiotic stress including heat stress. These MTAs could be potential targets for further validation study and may be used in marker-assisted breeding for improving wheat grain yield under post-anthesis heat stress conditions. This is the first study to identify novel QTLs associated with SF and SHI which represent the major components of grain number and grain weight, respectively, in wheat.