Abstract
Key messageChromosome regions affecting grain yield, grain yield components and plant water status were identified and validated in fall-sown spring wheats grown under full and limited irrigation.Increases in wheat production are required to feed a growing human population. To understand the genetic basis of grain yield in fall-sown spring wheats, we performed a genome-wide association study (GWAS) including 262 photoperiod-insensitive spring wheat accessions grown under full and limited irrigation treatments. Analysis of molecular variance showed that 4.1% of the total variation in the panel was partitioned among accessions originally developed under fall-sowing or spring-sowing conditions, 11.7% among breeding programs within sowing times and 84.2% among accessions within breeding programs. We first identified QTL for grain yield, yield components and plant water status that were significant in at least three environments in the GWAS, and then selected those that were also significant in at least two environments in a panel of eight biparental mapping populations. We identified and validated 14 QTL for grain yield, 15 for number of spikelets per spike, one for kernel number per spike, 11 for kernel weight and 9 for water status, which were not associated with differences in plant height or heading date. We detected significant correlations among traits and colocated QTL that were consistent with those correlations. Among those, grain yield and plant water status were negatively correlated in all environments, and six QTL for these traits were colocated or tightly linked (< 1 cM). QTL identified and validated in this study provide useful information for the improvement of fall-sown spring wheats under full and limited irrigation.
Highlights
Wheat (Triticum aestivum L.) is an important crop for global food security that provides roughly one-fifth of the daily calories and dietary proteins consumed by the human population (FAOSTAT 2015)
The close relationship between the wheat lines from SDK and University of Minnesota (UMN) is evident in both the STRUCTURE and principal component analyses (PCA, Fig. 1b)
We found nine Heading date (HD) and HT QTL that were colocated with grain yield, yield components and water status QTL (Table 5), which is consistent with the significant correlations among these traits (Table 3)
Summary
Wheat (Triticum aestivum L.) is an important crop for global food security that provides roughly one-fifth of the daily calories and dietary proteins consumed by the human population (FAOSTAT 2015). More than 700 million metric tons of wheat are produced every year, further increases are required to feed a rapidly growing human population. These increases need to be achieved in environments with changing climatic conditions and with increasing limitations in water and agricultural land (Shiferaw et al 2013; Curtis and Halford 2014). A better understanding of the genetic basis of yield and yield components under limited irrigation conditions will be required for securing the necessary increases in wheat production. A narrow definition of water stress is required to identify genes affecting
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