Plant growth and cultivation under environmental stresses

我们研究了植物适应环境胁迫的机制。(1)利用水稻和大麦的增重性突变体发现了一种新的植物增重现象。此外，我们还发现重力对葫芦属植物幼苗的重力形态形成具有负向控制作用，这与生长素浓度阈值理论有关。通过对生长素诱导基因及其转录因子的克隆和表达分析，建立了生长素调控重力负调控的工作假说。(2)红芒麦品种对赤霉素诱导第一节间强伸长的超敏感，对半干旱区深播条件具有较强的耐性。令人惊讶的是，培养基中钾的存在对于ga诱导的伸长是绝对必要的。(3)建立了黄瓜和拟南芥根系亲水性研究的实验体系。研究发现，生长素运输和分布、钙离子、脱落酸和内切木聚糖转移酶在根嗜水性中起重要作用。(4)建立了大麦生殖生长高温损伤的模型系统。提示高温胁迫下雄性不育可能与钙依赖性蛋白激酶的表达有关。通过对基因表达的序列分析，我们还发现了一些在高温下可以被诱导或抑制的基因。我们克隆了几个与植物上述反应有关的基因，至少部分解释了植物对引力场和干旱等特定环境的适应机制。本研究成果可为植物新品种的开发和植物生长调控方法的开发提供指导，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.