Wei Zexiu, Zeng Xingquan, Qin Cheng, Wang Yulin, Bai Lijun, Xu Qijun, Yuan Hongjun, Tang Yawei, Nyima Tashi
Tibet Academy of Agricultural and Animal Husbandry SciencesLhasa, China; State Key Laboratory of Barley and Yak Genetic Resources and ImprovementLhasa, China; Institute of Agricultural Resources and Environment Science, Tibet Academy of Agricultural and Animal Husbandry SciencesLhasa, China.
Tibet Academy of Agricultural and Animal Husbandry SciencesLhasa, China; State Key Laboratory of Barley and Yak Genetic Resources and ImprovementLhasa, China; Agricultural Research Institute, Tibet Academy of Agricultural and Animal Husbandry SciencesLhasa, China.
Front Plant Sci. 2016 Jul 21;7:1067. doi: 10.3389/fpls.2016.01067. eCollection 2016.
Nitrogen (N) deprivation or excess can lead to dramatic phenotype change, disrupt important biological processes, and ultimately limit plant productivity. To explore genes in Tibetan hulless barley responsive to varied N stress, we utilized a comparative transcriptomics method to investigate gene expression patterns under three nitrate treatments. The transcriptome of the control (optimal-nitrate, ON) sample was compared with that of free-nitrate (FN), low-nitrate (LN), and high-nitrate (HN) treatment samples, identifying 2428, 1274, and 1861 genes, respectively, that exhibited significant differences in transcript abundance. Among these, 9 genes encoding ribulose bisphosphate carboxylases exhibited up-regulated expression under varied N stress. We further compared FN vs. ON and LN vs. ON to investigate the impact of stress degree on gene expression. With the aggravation of stress, more genes were differentially expressed and thus possibly involved in the response to nitrogen deficiency. Cluster and functional enrichment analysis indicated that the differentially expressed genes (DEGs) in FN were highly enriched in response to stress, defense response, and gene expression regulation. Comprehensive comparison analysis further suggested that Tibetan hulless barley could respond to varied N stress by regulating multiple common biological processes and pathways such as nitrogen metabolism, carbon metabolism, and photosynthesis. A large number of specific DEGs involved in diverse biological processes were also detected, implying differences in the potential regulatory patterns of low- and high-N stress response. Notably, we also identified some NIN-like proteins and other transcription factors significantly modulated by these stresses, suggesting the involvement of these transcription factors in N stress response. To our knowledge, this study is the first investigation of the Tibetan hulless barley transcriptome under N stress. The identified N-stress-related genes may provide resources for genetic improvement and promote N use efficiency.
氮素（N）缺乏或过量会导致显著的表型变化，扰乱重要的生物过程，并最终限制植物生产力。为了探索青稞对不同氮胁迫的响应基因，我们采用比较转录组学方法研究了三种硝酸盐处理下的基因表达模式。将对照（最佳硝酸盐，ON）样本的转录组与无硝酸盐（FN）、低硝酸盐（LN）和高硝酸盐（HN）处理样本的转录组进行比较，分别鉴定出2428、1274和1861个在转录丰度上表现出显著差异的基因。其中，9个编码核酮糖二磷酸羧化酶的基因在不同氮胁迫下表达上调。我们进一步比较了FN与ON以及LN与ON，以研究胁迫程度对基因表达的影响。随着胁迫的加剧，更多基因差异表达，因此可能参与了对氮缺乏的响应。聚类和功能富集分析表明，FN中的差异表达基因（DEGs）在应激反应、防御反应和基因表达调控方面高度富集。综合比较分析进一步表明，青稞可以通过调节氮代谢、碳代谢和光合作用等多种常见生物过程和途径来响应不同的氮胁迫。还检测到大量参与不同生物过程的特异性DEGs，这意味着低氮和高氮胁迫响应的潜在调控模式存在差异。值得注意的是，我们还鉴定出一些受这些胁迫显著调节的NIN样蛋白和其他转录因子，表明这些转录因子参与了氮胁迫响应。据我们所知，本研究是首次对氮胁迫下青稞转录组进行的研究。鉴定出的与氮胁迫相关的基因可能为遗传改良提供资源，并提高氮利用效率。
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