Browsing by Author "Brasier, Kyle G."
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- Accelerated senescence and nitrogen remobilization in flag leaves enhance nitrogen use efficiency in soft red winter wheatAlpuerto, Jasper B.; Brasier, Kyle G.; Griffey, Carl A.; Thomason, Wade E.; Fukao, Takeshi (2021-01)Wheat (Triticum aestivum L.) production requires a large amount of nitrogen (N) supply because growers aim to achieve high grain yield and appropriate grain protein content simultaneously. A comprehensive understanding of the mechanisms that underpin efficient N usage at limited N in wheat can facilitate the development of new N-saving varieties in this major crop. Here, we performed comparative analysis of flag leaf responses to N availability in soft red winter wheat with contrasting N use efficiency (NUE); VA08MAS-369 (high NUE) and VA07W-415 (low NUE). This study demonstrated that accelerated senescence along with enhanced breakdown of protein and starch in flag leaves was correlated with higher grain yield, NUE for grain yield, and NUE for grain protein under N limitation. The more dramatic reductions in flag leaf N compounds and carbohydrate reserves in VA08MAS-369 were linked with significantly elevated expression of genes and enzymes associated with these metabolic pathways in this high NUE genotype. Consistent with the gene expression data, nitrate reductase, glutamine synthetase, and NAD-dependent glutamate dehydrogenase activities were highly induced under limited N in VA08MAS-369. It was previously reported that accelerated senescence contributes to increased grain protein content in wheat under regular N supply. This study provides molecular and physiological evidence that vigorous senescence and N remobilization also benefit grain yield under N deprivation.
- Differential responses of grain yield, grain protein content and their associated traits to nitrogen supply in soft red winter wheatTamang, Bishal Gole; Brasier, Kyle G.; Thomason, Wade E.; Griffey, Carl A.; Fukao, Takeshi (2017)Increased application of nitrogen fertilizers has significantly raised grain yield and protein concentration in wheat. However, only 30–50% of applied fertilizer nitrogen are usually utilized by the plant. In this study, four soft red winter wheat genotypes (Triticum aestivum L., IL07-4415, MD05W10208-11-8, OH06-150-57 and Sisson) were grown under three different nitrogen regimes (high, medium, and low) in a greenhouse, and grain yield, grain protein concentration, nitrogen use efficiency (NUE) and their associated traits were evaluated. Among the four genotypes, a high-yielding cultivar, Sisson, exhibited superior performance in terms of grain weight plant–1 and NUE for yield (NUEY) at low nitrogen due to maintained grain number spike–1 and harvest index. Significant yield losses due to nitrogen limitation were attributable to reduced spike number plant–1 and grain number spike–1 in the other genotypes. Interestingly, a linear relationship between NUEY and NUE for grain protein (NUEP) was detected at high (R2 = 0.67) and low (R2 = 0.42) nitrogen; both of these traits were positively correlated with grain number spike–1, 1000-seed weight, and harvest index under nitrogen-limited conditions (R2 = 0.35–0.48). These results suggest that simultaneous improvement of NUEY and NUEP could be achieved through the selection of the three yield components (grain number spike–1, 1000-seed weight, and harvest index) at low nitrogen.
- Identification of quantitative trait loci associated with nitrogen use efficiency in winter wheatBrasier, Kyle G.; Ward, Brian P.; Smith, Jared; Seago, John E.; Oakes, Joseph C.; Balota, Maria; Davis, Paul H.; Fountain, Myron O.; Brown-Guedira, Gina L.; Sneller, Clay H.; Thomason, Wade E.; Griffey, Carl A. (2020-02-24)Maintaining winter wheat (Triticum aestivum L.) productivity with more efficient nitrogen (N) management will enable growers to increase profitability and reduce the negative environmental impacts associated with nitrogen loss. Wheat breeders would therefore benefit greatly from the identification and application of genetic markers associated with nitrogen use efficiency (NUE). To investigate the genetics underlying N response, two bi-parental mapping populations were developed and grown in four site-seasons under low and high N rates. The populations were derived from a cross between previously identified high NUE parents (VA05W-151 and VA09W-52) and a shared common low NUE parent, 'Yorktown.' The Yorktown x VA05W-151 population was comprised of 136 recombinant inbred lines while the Yorktown x VA09W-52 population was comprised of 138 doubled haploids. Phenotypic data was collected on parental lines and their progeny for 11 N-related traits and genotypes were sequenced using a genotyping-by-sequencing platform to detect more than 3,100 high quality single nucleotide polymorphisms in each population. A total of 130 quantitative trait loci (QTL) were detected on 20 chromosomes, six of which were associated with NUE and N-related traits in multiple testing environments. Two of the six QTL for NUE were associated with known photoperiod (Ppd-D1 on chromosome 2D) and disease resistance (FHB-4A) genes, two were reported in previous investigations, and one QTL, QNue.151-1D, was novel. The NUE QTL on 1D, 6A, 7A, and 7D had LOD scores ranging from 2.63 to 8.33 and explained up to 18.1% of the phenotypic variation. The QTL identified in this study have potential for marker-assisted breeding for NUE traits in soft red winter wheat.