Karunarathne Sakura D, Han Yong, Zhang Xiao-Qi, Zhou Gaofeng, Hill Camilla B, Chen Kefei, Angessa Tefera, Li Chengdao
Western Barley Genetics Alliance, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA, Australia.
Western Australian State Agricultural Biotechnology Centre, Murdoch University, Perth, WA, Australia.
Front Plant Sci. 2020 Sep 4;11:571912. doi: 10.3389/fpls.2020.571912. eCollection 2020.
Nitrogen (N) fertilizer is largely responsible for barley grain yield potential and quality, yet excessive application leads to environmental pollution and high production costs. Therefore, efficient use of N is fundamental for sustainable agriculture. In the present study, we investigated the performance of 282 barley accessions through hydroponic screening using optimal and low NHNO treatments. Low-N treatment led to an average shoot dry weight reduction of 50%, but there were significant genotypic differences among the accessions. Approximately 20% of the genotypes showed high (>75%) relative shoot dry weight under low-N treatment and were classified as low-N tolerant, whereas 20% were low-N sensitive (≤55%). Low-N tolerant accessions exhibited well-developed root systems with an average increase of 60% in relative root dry weight to facilitate more N absorption. A genome-wide association study (GWAS) identified 66 significant marker trait associations (MTAs) conferring high nitrogen use efficiency, four of which were stable across experiments. These four MTAs were located on chromosomes 1H(1), 3H(1), and 7H(2) and were associated with relative shoot length, relative shoot and root dry weight. Genes corresponding to the significant MTAs were retrieved as candidate genes, including members of the asparagine synthetase gene family, several transcription factor families, protein kinases, and nitrate transporters. Most importantly, the () was identified as a promising candidate on 7H for root and shoot dry weight. The identified candidate genes provide new insights into our understanding of the molecular mechanisms driving nitrogen use efficiency in barley and represent potential targets for genetic improvement.
氮肥在很大程度上决定了大麦的籽粒产量潜力和品质，但过量施用会导致环境污染和高生产成本。因此，高效利用氮肥是可持续农业的基础。在本研究中，我们通过水培筛选，利用最佳和低NHNO处理研究了282份大麦种质的表现。低氮处理导致地上部干重平均降低50%，但种质间存在显著的基因型差异。约20%的基因型在低氮处理下表现出较高（>75%）的相对地上部干重，被归类为耐低氮型，而20%为低氮敏感型（≤55%）。耐低氮种质表现出发达的根系，相对根干重平均增加60%，以促进更多的氮吸收。全基因组关联研究（GWAS）确定了66个赋予高氮利用效率的显著标记-性状关联（MTA），其中4个在各实验中稳定。这4个MTA位于1H(1)、3H(1)和7H(2)染色体上，与相对地上部长度、相对地上部和根干重相关。与显著MTA对应的基因被检索为候选基因，包括天冬酰胺合成酶基因家族成员、几个转录因子家族、蛋白激酶和硝酸盐转运蛋白。最重要的是，（此处原文缺失信息）被确定为7H染色体上根和地上部干重的一个有前景的候选基因。所鉴定的候选基因为我们理解大麦中驱动氮利用效率的分子机制提供了新的见解，并代表了遗传改良的潜在靶点。
