title: Effect of post-silking drought on nitrogen partitioning and gene expression patterns of glutamine synthetase and asparagine synthetase in two maize (Zea mays L.) varieties.
abstract: Glutamine synthetase (GS) and asparagine synthetase (AS) are proposed to have important function in plant nitrogen (N) remobilization, but their roles under drought stress are not well defined. In this study, the expression dynamics of GS and AS genes were analyzed in two maize varieties (ZD958 and NH101) in relation to post-silking drought stress induced nitrogen partitioning. ZD958 was a 'stay-green' variety with 5% nitrogen harvest index (NHI) lower than NH101. From silking to maturity, the amount of nitrogen remobilized from ear-leaves in ZD958 was evidently lower than NH101, and post-silking drought stress increased the nitrogen remobilization for both varieties. In ear-leaves, the expression of ZmGln1-3 was enhanced under drought stress. Three AS genes (ZmAS1, ZmAS2 and ZmAS3) were differentially regulated by post-silking drought treatment, of which the expression of ZmAS3 was stimulated at late stage of leaf senescence. In NH101, the expression level of ZmAS3 was markedly higher than that in ZD958. In developing grains, there were no significant differences in expression patterns of GS and AS genes between well water and drought treated plants. Drought stress altered maize N partitioning at the whole-plant level, and the up-regulation of GS and AS genes may contribute to the higher leaf nitrogen remobilization when exposed to drought treatments.
authors.affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Meiling
authors.initials: M
authors.lastname: Wang
authors.affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Zhang
authors.affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Yadong
authors.initials: Y
authors.lastname: Xu
authors.affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Qin
authors.affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China. Electronic address: wenxiaoxia6811@163.com.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Wen
mesh_terms: D001217:Aspartate-Ammonia Ligase / Q000096:biosynthesis*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005974:Glutamate-Ammonia Ligase / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism*; D013312:Stress, Physiological; D003313:Zea mays / Q000201:enzymology*
chemical_list: D001217:Aspartate-Ammonia Ligase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen
keywords: Asparagine synthetase; Drought; Glutamine synthetase; Maize; Nitrogen