控制水稻胚乳淀粉合成代谢若干关键酶基因对花后高温的响应表达

以稻米品质温度敏感型的早籼稻品种嘉早935为材料，利用人工气候箱控温试验和实时荧光定量PCR技术，探讨了不同灌浆温度(日均温分别为22和32 ℃)处理下胚乳淀粉分支酶(SBE)、淀粉去分支酶(DBE)和淀粉合酶(SS)的10个同工型基因(sbe1、sbe3、sbe4、pul、isa1、isa2、isa3、Wx、sss1和sss2a)的相对表达量差异及动态变化特征.结果表明: 淀粉合成相关功能基因对水稻灌浆期高温胁迫的响应表达方式存在明显差异，而且因同工型的类型而不同.在高温处理下，sbe1和sbe3的相对表达量显著下降，二者属于SBE类基因中对高温胁迫较敏感的主要同工型；DBE基因中，pul属于高表达的同工型，而且其对高温胁迫响应比isa1、isa2和isa3敏感；在Wx、sss1和sss2a中，sss2a的相对表达量显著低于sss1和Wx, 但sss2a和sss1对高温胁迫响应比Wx敏感，因此二者可能也是高温胁迫对胚乳淀粉结构进行调控的重要位点，尤其在水稻灌浆的中后期发挥重要作用.

Taxonomy and phylogenetics of the genus Phaeocystis: Research progress

Phaeocystis (Haptophyceae) has its special characteristics in physiology, biochemistry, and ecology, and is recognized as a group of worldwide harmful and toxic algae. It has a heterogenic life history involving sexual reproduction between single cells and colonies. The single cells have three types, i.e., non-flagellate cell, macrozoospore, and microzoospore. The transformation between single cells and colonies is affected by nutrients, light, solid matrix, and water body disturbance, etc. The tiny body size and the polymorphic forms cause many flaws in the morphology-based taxonomy of Phaeocystis. The application of molecular marker technology promotes the classification and phylogenetics of Phaeocystis greatly. The molecular markers for Phaeocystis classification and phylogenetics mainly include both nuclear and chloroplast genes. The phylogeny based on 18S rDNA suggests that Phaeocystis originates as a warm-water species with a global distribution. P. jahnii and P. cordata are diverged at earlier time, and the cold-water species isolated from warm-water ancestors may be diverged sixty million years ago. A total of seven geographical strains of Phaeocystis in China coasts have been recorded, but the study progress of their origin and spreading is still slow. This paper reviewed the taxonomy, life history, and phylogeny of Phaeocystis, and its origin, distribution, and spreading pattern in China. The future study on the taxonomy and phylogenetics of Phaeocystis was prospected.