Le Tuan Ngoc, Blomstedt Cecilia K, Kuang Jianbo, Tenlen Jennifer, Gaff Donald F, Hamill John D, Neale Alan D
School of Biological Sciences, Monash University, Vic. 3800, Australia.
Funct Plant Biol. 2007 Aug;34(7):589-600. doi: 10.1071/FP06231.
The desiccation tolerant grass Sporobolus stapfianus Gandoger can modulate cellular processes to prevent the imposition of irreversible damage to cellular components by water deficit. The cellular processes conferring this ability are rapidly attenuated by increased water availability. This resurrection plant can quickly restore normal metabolism. Even after loss of more than 95% of its total water content, full rehydration and growth resumption can occur within 24 h. To study the molecular mechanisms of desiccation tolerance in S. stapfianus, a cDNA library constructed from dehydration-stressed leaf tissue, was differentially screened in a manner designed to identify genes with an adaptive role in desiccation tolerance. Further characterisation of four of the genes isolated revealed they are strongly up-regulated by severe dehydration stress and only in desiccation-tolerant tissue, with three of these genes not being expressed at detectable levels in hydrated or dehydrating desiccation-sensitive tissue. The nature of the putative proteins encoded by these genes are suggestive of molecular processes associated with protecting the plant against damage caused by desiccation and include a novel LEA-like protein, and a pore-like protein that may play an important role in peroxisome function during drought stress. A third gene product has similarity to a nuclear-localised protein implicated in chromatin remodelling. In addition, a UDPglucose glucosyltransferase gene has been identified that may play a role in controlling the bioactivity of plant hormones or secondary metabolites during drought stress.
耐旱草种斯氏鼠尾粟（Sporobolus stapfianus Gandoger）能够调节细胞过程，以防止水分亏缺对细胞成分造成不可逆转的损害。赋予这种能力的细胞过程会因水分供应增加而迅速减弱。这种复苏植物能够迅速恢复正常代谢。即使其总含水量损失超过95%，在24小时内仍可完全复水并恢复生长。为了研究斯氏鼠尾粟耐旱性的分子机制，我们从脱水胁迫的叶片组织构建了一个cDNA文库，并以一种旨在鉴定在耐旱性中具有适应性作用的基因的方式进行了差异筛选。对分离出的四个基因的进一步表征表明，它们在严重脱水胁迫下强烈上调，且仅在耐旱组织中表达，其中三个基因在水合或脱水敏感组织中未检测到表达。这些基因编码的假定蛋白质的性质表明它们参与了保护植物免受干旱损害的分子过程，包括一种新型的类胚胎发育晚期丰富蛋白（LEA-like protein），以及一种可能在干旱胁迫期间过氧化物酶体功能中起重要作用的孔状蛋白。第三个基因产物与一种参与染色质重塑的核定位蛋白相似。此外，还鉴定出一个UDP葡萄糖糖基转移酶基因，它可能在干旱胁迫期间控制植物激素或次生代谢物的生物活性方面发挥作用。
