磷脂酶Dδ参与植物的低温驯化过程

对经低温驯化和未经低温驯化的磷脂酶Dδ（PLDδ）基因敲除突变体与野生型植株进行冻害胁迫处理后,比较2种基因型植株的抗冻性。结果发现,经低温驯化的PLDδ敲除突变体的抗冻性明显低于野生型,而未经低温驯化的PLD礅除突变体与野生型的抗冻性没有显著差异,表明PLDδ参与植物的低温驯化过程。对PLDδ的作用途径进行分析,发现PLDδ在低温驯化过程中不参与抗氧化酶活性的调节,对脯氨酸和可溶性糖的积累起负调节作用,但是参与低温信号转导物质ABA诱导抗冻性的过程。     

Efficiency of cold hardiness induction by desiccation stress in four winter cereals

A number of defined desiccation treatments without low temperature exposure were able to induce freezing tolerance in 20 cultivars of winter cereals. A maximal degree of freezing tolerance was induced in epicotyls at 24°C in 24 hours at 40% relative humidity in rye and wheat, 7 days at 54% RH in barley, and 4 days at 70% RH in oats. Freezing tolerance was not correlated to water content of the plants after desiccation treatment but was related to the genetic capacity of the cultivars to frost harden. Levels of freezing tolerance induced by desiccation were similar to those induced by cold acclimation in rye and wheat, but considerably less in barley and oats. This is associated with a more rapid desiccation injury in barley and oats, precluding the completion of the hardening process.     

磷脂酶Dδ参与植物的低温驯化过程

对经低温驯化和未经低温驯化的磷脂酶Dδ (PLDδ)基因敲除突变体与野生型植株进行冻害胁迫处理后, 比较2种基因型植株的抗冻性。结果发现, 经低温驯化的PLDδ敲除突变体的抗冻性明显低于野生型, 而未经低温驯化的PLDδ敲除突变体与野生型的抗冻性没有显著差异, 表明PLDδ参与植物的低温驯化过程。对PLDδ的作用途径进行分析, 发现PLDδ在低温驯化过程中不参与抗氧化酶活性的调节, 对脯氨酸和可溶性糖的积累起负调节作用, 但是参与低温信号转导物质ABA诱导抗冻性的过程。     

Sugars regulate cold-induced gene expression and freezing-tolerance in barley cell cultures

The hypothesis that the extracellular concentration of sugars helps regulate the acclimation of plant cells to cold was tested in this work. Suspension cultures were used to control the concentration of sugars in the medium supplied to barley cell cultures (Hordeum vulgare L. cv. Igri), replacing the medium daily to help maintain the concentration. Freezing tolerance and the levels of mRNA expression of the stress-response genes blt4.9 (coding for a non- specific lipid transfer protein) and dhn1 (coding for a dehydrin) were measured. Similar levels of freezing-tolerance and gene expression were obtained in the experiments as occur during cold-acclimation in the crown of the whole plant. In the cell cultures, cold (6/2 degrees C) did not induce an increase in freezing tolerance or in the expression of detectable levels of blt4.9 or dhn1 mRNAs when only 1 g l-1 sucrose was supplied. However, the cells in this low sucrose medium in the cold were not sugar-starved, indicating that this did not explain the failure of the cells to acclimate when grown in the cold environment. Ten g l-1 sucrose supplied to cells grown in the warm (25 degrees C) induced acclimation to freezing and up-regulation of expression of blt4.9 and dhn1 mRNAs. Osmolality of the medium did not explain this. Thirty g l-1 sucrose induced yet higher levels of freezing tolerance and of blt4.9 and dhn1 mRNAs in cultures grown in either the cold or the warm environment. The results implicate sugars in the regulation of cold acclimation     

植物抗寒及其基因表达研究进展

植物经过逐渐降低的温度从而提高抗寒能力 ,这个过程被人们称为低温驯化。植物低温驯化过程是一个复杂的生理、生化和能量代谢变化过程 ,这些变化主要包括膜系统的稳定性、可溶性蛋白的积累和小分子渗透物质 ,比如脯氨酸、糖等 ,这些变化中的一些是植物抗寒必需的 ,而另外一些变化不是必需的。主要对冷害和低温生理生化变化、低温诱导表达基因的功能和作用、低温驯化的调节机制及其信号转导方面进行了综述。通过差别筛选 c DNA文库的方法已经鉴定了许多低温诱导表达、进而提高植物抗寒能力的基因 ,其中有脱水素、COR基因和 CBF1转录因子等。低温信号的感受、转导和调节表达是低温驯化的关键环节 ,低温信号的转导过程与干旱胁迫之间具有一定的交叉 ,这为利用 ABA等来提高植物抗寒能力成为可能 ,相信不久的将来人们可以通过提高植物抗寒能力从而增加经济产量成为现实。     

植物抗冻机理研究新进展：抗冻基因表达及其功能

综述了迄今业已分离和鉴定的低温诱导表达的抗冻基因,以及通过染色体基因制图方法褐示和证实的抗冻性基因,并着重地介绍了这些抗冻基因在提高植物抗冻能力上的功能。这些抗冻基因表达合成的新多肽具3有高度的亲水性,起着保护和稳定细胞膜结构的作用,从而防止冰冻伤害,提高植物的抗冻能力,同时还介绍了抗冻基因表达中的某些调节因子,其中尤其值得注意的是,CBF基因似乎有可能作为抗冻基因表达的“主开关”,以及Ca^2 作为植物细胞的第二信使在传递低温信号,启动和调节抗冻基因表达中可能的重要作用,这些研究结果,不仅为阐明植物的抗冻机理提供了新的证据,而且为改良农作物的抗寒性提供了新的启示。     

植物抗冻机理研究新进展：抗冻基因表达及其功能

综述了迄今业已分离和鉴定的低温诱导表达的抗冻基因,以及通过染色体基因制图方法揭示和证实的抗冻性基因。并着重地介绍了这些抗冻基因在提高植物抗冻能力上的功能。这些抗冻基因表达合成的新多肽具有高度的亲水性,起着保护和稳定细胞膜结构的作用,从而防止冰冻伤害、提高植物的抗冻能力。同时还介绍了抗冻基因表达中的某些调节因子,其中尤其值得注意的是,CBF基因似乎有可能作为抗冻基因表达的“主开关”,以及Ca2+作为植物细胞的第二信使在传递低温信号、启动和调节抗冻基因表达中可能的重要作用。这些研究结果,不仅为阐明植物的抗冻机理提供了新的证据,而且为改良农作物的抗寒性提供了新的启示。