Ren Meng Yun, Feng Ren Jun, Shi Hou Rui, Lu Li Fang, Yun Tian Yan, Peng Ming, Guan Xiao, Zhang Heng, Wang Jing Yi, Zhang Xi Yan, Li Cheng Liang, Chen Yan Jun, He Peng, Zhang Yin Dong, Xie Jiang Hui
College of Agronomy, Hainan University, Haikou, P.R. China.
Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (CATAS), Haikou, P.R. China.
PLoS One. 2017 May 23;12(5):e0177621. doi: 10.1371/journal.pone.0177621. eCollection 2017.
Drought is the one of the most important environment stresses that restricts crop yield worldwide. Cassava (Manihot esculenta Crantz) is an important food and energy crop that has many desirable traits such as drought, heat and low nutrients tolerance. However, the mechanisms underlying drought tolerance in cassava are unclear. Ethylene signaling pathway, from the upstream receptors to the downstream transcription factors, plays important roles in environmental stress responses during plant growth and development. In this study, we used bioinformatics approaches to identify and characterize candidate Manihot esculenta ethylene receptor genes and transcription factor genes. Using computational methods, we localized these genes on cassava chromosomes, constructed phylogenetic trees and identified stress-responsive cis-elements within their 5' upstream regions. Additionally, we measured the trehalose and proline contents in cassava fresh leaves after drought, osmotic, and salt stress treatments, and then it was found that the regulation patterns of contents of proline and trehalose in response to various dehydration stresses were differential, or even the opposite, which shows that plant may take different coping strategies to deal with different stresses, when stresses come. Furthermore, expression profiles of these genes in different organs and tissues under non-stress and abiotic stress were investigated through quantitative real-time PCR (qRT-PCR) analyses in cassava. Expression profiles exhibited clear differences among different tissues under non-stress and various dehydration stress conditions. We found that the leaf and tuberous root tissues had the greatest and least responses, respectively, to drought stress through the ethylene signaling pathway in cassava. Moreover, tuber and root tissues had the greatest and least reponses to osmotic and salt stresses through ethylene signaling in cassava, respectively. These results show that these plant tissues had differential expression levels of genes involved in ethylene signaling in response to the stresses tested. Moreover, after several gene duplication events, the spatiotemporally differential expression pattern of homologous genes in response to abiotic and biotic stresses may imply their functional diversity as a mechanism for adapting to the environment. Our data provide a framework for further research on the molecular mechanisms of cassava resistance to drought stress and provide a foundation for breeding drought-resistant new cultivars.
干旱是限制全球作物产量的最重要环境胁迫之一。木薯(Manihot esculenta Crantz)是一种重要的粮食和能源作物,具有许多优良性状,如耐旱、耐热和耐低养分。然而,木薯耐旱的潜在机制尚不清楚。乙烯信号通路,从上游受体到下游转录因子,在植物生长发育过程中的环境胁迫反应中发挥重要作用。在本研究中,我们使用生物信息学方法来鉴定和表征候选木薯乙烯受体基因和转录因子基因。通过计算方法,我们将这些基因定位到木薯染色体上,构建系统发育树,并在其5'上游区域鉴定胁迫响应顺式元件。此外,我们测量了干旱、渗透和盐胁迫处理后木薯鲜叶中的海藻糖和脯氨酸含量,结果发现脯氨酸和海藻糖含量对各种脱水胁迫的响应调控模式存在差异,甚至相反,这表明当胁迫来临时,植物可能采取不同的应对策略来应对不同的胁迫。此外,通过木薯的定量实时PCR(qRT-PCR)分析,研究了这些基因在非胁迫和非生物胁迫下不同器官和组织中的表达谱。在非胁迫和各种脱水胁迫条件下,不同组织的表达谱表现出明显差异。我们发现,通过木薯中的乙烯信号通路,叶和块根组织对干旱胁迫的反应分别最大和最小。此外,通过木薯中的乙烯信号,块茎和根组织对渗透和盐胁迫的反应分别最大和最小。这些结果表明,这些植物组织在响应所测试的胁迫时,参与乙烯信号传导的基因表达水平存在差异。此外,经过几次基因复制事件后,同源基因在时空上对非生物和生物胁迫的差异表达模式可能暗示它们作为适应环境机制的功能多样性。我们的数据为进一步研究木薯抗旱胁迫的分子机制提供了框架,并为培育抗旱新品种奠定了基础。