Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.
Plant Physiol Biochem. 2010 Apr;48(4):256-64. doi: 10.1016/j.plaphy.2009.12.005. Epub 2010 Feb 1.
Heat shock proteins (HSPs) are induced not only under heat stress conditions but also under other environmental stresses such as water stress. In plants, HSPs families are larger than those of other eukaryotes. In order to elucidate a possible connection between HSP expression and photosynthetic acclimation or conditioning, we conducted a water stress experiment in loblolly pine (Pinus taeda L.) seedlings involving progressive treatment consisting of one cycle of mild stress (-1 MPa) followed by two cycles of severe stress (-1.7 MPa). Net photosynthesis was measured at each stress level. Photosynthetic acclimation occurred in the progressive treatment after the first cycle, but not in the severe treatment, suggesting that a cycle of mild stress conditioned the trees to adapt to a more severe stress. Real time results indicated specific patterns in needles in the expression of HSP70, HSP90 and sHSP genes for each treatment, both at maximum stress and at recovery. We identified a pine homolog to GRP94 (ER resident HSP90) that was induced after rehydration coincident with acclimation. Further analysis of the promoter region of the pine GRP94 showed putative cis-elements associated with water stress and rehydration, corresponding to the expression pattern observed in our experiment.
热休克蛋白（HSPs）不仅在热应激条件下，而且在其他环境应激下如水分胁迫下被诱导产生。在植物中，HSPs 家族比其他真核生物的更大。为了阐明 HSP 表达与光合作用适应或驯化之间可能存在的联系，我们在火炬松（Pinus taeda L.）幼苗中进行了水分胁迫实验，包括一个轻度胁迫（-1 MPa）周期和两个严重胁迫（-1.7 MPa）周期的渐进处理。在每个胁迫水平下测量净光合作用。渐进处理在第一周期后发生光合作用适应，但在严重处理中没有发生，这表明轻度胁迫周期使树木适应更严重的胁迫。实时结果表明，在每个处理的针叶中，HSP70、HSP90 和 sHSP 基因的表达都有特定的模式，无论是在最大胁迫下还是在恢复时。我们鉴定了一个与 GRP94（内质网驻留 HSP90）同源的松树同源物，该同源物在与适应同时发生的再水合后被诱导。对松树 GRP94 启动子区域的进一步分析显示，与水分胁迫和再水合相关的顺式元件与我们实验中观察到的表达模式相对应。
