Plant growth and cultivation under environmental stresses

我们已经研究了植物适应环境胁迫条件的机制。(1)我们利用水稻和大麦的无重力向异性突变体发现了一种新的植物重力形态，并进一步发现葫芦科植物的重力形态发生受重力负控制，这可以用生长素浓度阈值理论来解释。通过对生长素诱导基因及其转录因子的克隆和表达分析，建立了生长素对重力负调控的工作假说。(2)红芒麦是一种耐深播的小麦品种，它对赤霉素超敏感，能诱导第一节间的伸长。令人惊讶的是，培养基中钾的存在是GA诱导的伸长所绝对需要的。(3)建立了黄瓜和拟南芥根向水性研究的实验体系。研究发现，生长素的运输与分配、钙离子、脱落酸和内切木葡聚糖转移酶在根系向水性化中起重要作用。(4)建立了高温对大麦生殖生长伤害的模型体系。高温胁迫导致雄性不育的机制可能与钙依赖蛋白激酶的表达有关。我们还通过基因表达系列分析发现了一些可以被高温诱导或抑制的基因，并克隆了几个负责植物上述反应的基因，这些基因至少部分解释了植物适应重力场和干旱地区等特定环境的机制。本研究的成果可能会导致新的植物和植物生长调节方法的发展，以提高作物产量。

We have studied the mechanisms useful for the adaptation of plants to the conditions of environmental stresses.(1) We found a new gravimorphism of plants using agravitropic mutants of rice and barley.Furthermore, we discovered that gravimorphogenesis of cucurbitaceous seedlings was negatively controlled by gravity, which was accounted by the threshold theory of auxin concentration. By cloning and expression analysis of auxin-inducible genes and its transcriptional factor, we established a working hypothesis for the auxin regulation of the gravity's negative control.(2) A variety of wheat, Hong Mang Mai, was found to be tolerant to deep-seeding conditions in semi-arid area because it was super-sensitive to gibberellins in inducing strong elongation of the first internode. Surprisingly, the presence of potassium in culture media was absolutely required for the GA-induced elongation.(3) We established the experimental system for the study of hydrotropism in the roots of cucumber and Arabidopsis. It was found that auxin transport and distribution, calcium ion, abscisic acid and endo-xyloglucan transferase played important roles in root hydrotropism.(4) We established a model system for the study of the high-temperature-induced injury of the reproductive growth in barley. It was suggested that the expression of a calcium-dependent protein kinase was involved in the male sterility caused by high-temperature stress. We also discovered some genes that could be induced or suppressed in response to high temperature by adopting the serial analysis of gene expression.We have cloned several genes responsible for above responses of plants, which accounted, at least in part, for the mechanisms of plant adaptation to particular environment such as gravitational field and arid area. The accomplishments of the present study may lead to the development of new plants and regulatory methods of plant growth for improving crop yield.