青菜热水浴处理保绿机理研究

通过对热处理后青菜组织内部叶绿素-蛋白质牢固性、叶 绿素降解产物和过氧化物酶活性变化的检测,初步考察 了青菜热水浴处理的保绿机理。结果表明,叶绿素的降解 速率与叶绿素-蛋白质结合牢固性之间无显著相关性:热 处理抑制了脱镁叶绿素氧化酶的活性,使叶绿素降解中 间产物造成积累,进而对叶绿素酶和脱镁叶绿素螯合酶 形成反馈抑制,从而延缓了青菜叶片的黄化;热处理抑制 了过氧化物酶的活性,从而阻止了由过氧化物酶引起的 过氧化反应对叶绿体的伤害,减缓了叶绿素的降解。热水 浴处理影响了青菜蛋白质的合成,产生了热激蛋白 (HSPs)。

零式株型与长果枝型海岛棉叶片光合色素特性的比较研究

采用分光光度法对零式株型和长果枝型海岛棉两种株型9个品种的叶片光合色素特性进行比较研究。结果表明:零式株型海岛棉叶片的叶绿素a、b、(a+b)含量、类胡萝卜素含量、光合色素总量以及叶绿素/类胡萝卜素之比分别高于长果枝型海岛棉10.8％、150％、12.2％、4.8％、10.1％、7.5％,零式株型海岛棉叶片的叶绿素a/b值和叶绿素与蛋白质结合度分别低于长果枝型海岛棉3.6％、13.9％;零式株型海岛棉叶片的未知色素、紫黄质、叶绿素b、叶绿素a、叶黄素和胡萝卜素的层析迁移速率分别高于长果枝型海岛棉41.2％、20.5％、18.7％、17.3％、3.9％、o.2％;与长果枝型海岛棉相比,零式株型海岛棉的光合色素具有较高的可见光吸苏光谱和较低的紫外光吸收光谱。因而,零式株型海岛棉光能利用率高,光合速率高,能够积累较多的光合产物,有利于早熟丰产。

Target deletion of the AAA ATPase PpCDC48II in Physcomitrella patens results in freezing sensitivity after cold acclimation

CDC48 is a highly conserved protein in eukaryotes and belongs to the AAA （ATPase associated with a variety of cellular activities） superfamily. It can interact with many different cofactors and form protein complexes that play important roles in various cellular processes. According to the Physcomitrella patens database, one member of the ATPases, the cell cycle gene PpCDC4811, was cloned. PpCDC48II contains two typical ATPase modules and is highly homologous to AtCDC48A. PpCDC4811 was up-regulated in mRNA levels after incubation at 0~C for 36 and 72 h. To further elucidate protein function, we disrupted the PpCDC4811 gene by transforming P. patens with the corresponding linear genomic sequences. When treated to the same freezing stress, it was found that PpCDC4811 knockout plants were less resistant to freezing treatment than wild type after acclimation. This suggested that PpCDC481I was an essential gene for low-temperature-induced freezing tolerance in P. patens cells.