Understanding the Genetic Basis of Spike Fertility to Improve Grain Number, Harvest Index, and Grain Yield in Wheat Under High Temperature Stress Environments

Sumit Pradhan; Md Ali Babar; Kelly Robbins; Guihua Bai; Richard Esten Mason; Jahangir Khan; Dipendra Shahi; Muhsin Avci; Jia Guo; Mohammad Maksud Hossain; Madhav Bhatta; Mohamed Mergoum; Senthold Asseng; Paul St Amand; Salvador Gezan; Byung-Kee Baik; Ann Blount; Amy Bernardo

doi:10.3389/fpls.2019.01481

Understanding the Genetic Basis of Spike Fertility to Improve Grain Number, Harvest Index, and Grain Yield in Wheat Under High Temperature Stress Environments

Front Plant Sci. 2019 Nov 29:10:1481. doi: 10.3389/fpls.2019.01481. eCollection 2019.

Authors

Sumit Pradhan¹, Md Ali Babar¹, Kelly Robbins², Guihua Bai³, Richard Esten Mason⁴, Jahangir Khan¹, Dipendra Shahi¹, Muhsin Avci¹, Jia Guo¹, Mohammad Maksud Hossain¹, Madhav Bhatta⁵, Mohamed Mergoum⁶, Senthold Asseng⁷, Paul St Amand³, Salvador Gezan⁸, Byung-Kee Baik⁹, Ann Blount¹, Amy Bernardo¹⁰

Affiliations

¹ Department of Agronomy, University of Florida, Gainesville, FL, United States.
² School of Integrative Plant Science, Section of Plant Breeding and Genetics, Cornell University, Ithaca, NY, United States.
³ USDA-ARS, Manhattan, KS, United States.
⁴ Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR, United States.
⁵ Department of Agronomy, University of Wisconsin, Madison, WI, United States.
⁶ Department of Crop and Soil Sciences, University of Georgia, Griffin, GA, United States.
⁷ Agricultural and Biological Engineering, University of Florida, Gainesville, FL, United States.
⁸ School of Forest Resources and Conservation, University of Florida, Gainesville, FL, United States.
⁹ USDA-ARS, Wooster, OH, United States.
¹⁰ Department of Plant Pathology, Kansas State University, Manhattan, KS, United States.

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 3 years. GWAS identified 109 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.

Keywords: genome-wide association study; genotyping-by-sequencing; marker-assisted breeding; marker-trait associations; quantitative trait loci; single nucleotide polymorphisms; spike fertility; spike harvest index.