香石竹DcMAPK1和DcMAPK2的克隆及功能初#br# 步分析

 分离了香石竹（Dianthus caryophyllus）两个促分裂原活化蛋白质激酶（mitogen-ac-tivated protein kinase,MAPK）基因cDNA 全长,分别命名为DcMAPK1 和DcMAPK2,其中DcMAPK1 与拟南 芥AtMAPK6 高度同源。DcMAPK1 在香石竹花瓣衰老过程表达增加,乙烯处理显著促进其表达,瞬时抑 制DcMAPK1 后切花瓶插寿命显著延长。而DcMAPK2 在花瓣衰老过程中组成型表达,乙烯处理对其表达 无显著影响,瞬时抑制DcMAPK2 对切花瓶插寿命无显著影响。     

免耕抛栽水稻源库特性研究

近些年来,水稻免耕抛秧栽培在中国广西等部分地区发展迅速。为了探讨免耕抛栽水稻产量形成特点,以金优253(OryzasativaL.)为试验材料,以常耕抛栽水稻为对照,从叶面积大小、剑叶光合速率与衰老、库的大小及源库比率等方面研究了免耕抛栽水稻的源库特性。结果表明,免耕抛栽水稻早、晚季产量分别为5.97t/hm2和7.53t/hm2,常耕抛栽水稻分别为6.19t/hm2和7.63t/hm2,其产量差异在早季和晚季均不显著。与常耕抛栽水稻相比,免耕抛栽水稻的每穗总粒数和单位面积上的总粒数较多,各生育期的叶面积指数较大,灌浆期剑叶光合速率、蒸腾速率、气孔导度、叶绿素含量较高,而过氧化物酶和过氧化氢酶活性及丙二醛的含量较低,在生理上存在一定的优势。但是,免耕抛栽水稻的源库协调能力较差,粒叶比和结实率下降,致使免耕抛栽水稻在产量上表现出一定的劣势。免耕抛栽水稻粒叶比和结实率的下降是由于其生产的干物质更多地分配在叶片中、贮藏在茎鞘中的干物质在抽穗后向穗部运转的能力较差造成的。     

棉花叶片衰老生理研究进展

随着转基因棉花的大面积推广,棉花早衰发生加重,已经成为制约棉花发展的重要因素,有关早衰的研究成为学者关注的焦点。综述了近年来国内外有关棉花叶片衰老生理的研究结果,主要包括衰老过程中各种生理生化指标的变化特征,以及防止棉花叶片衰老的各种调控措施。文中概述了一些常用的棉花叶片衰老生理生化指标,如叶绿素、蛋白质、丙二醛(MDA)、活性氧清除系统(SOD、POD、CAT)、激素(生长素、细胞分裂素、赤霉素、脱落酸、乙烯、多胺)等。大量研究表明在棉花叶片衰老过程中叶绿素、蛋白质含量急剧下降,而MDA含量快速上升,活性氧清除系统酶活性产生相应的变化,各内源激素的含量也具有各自变化特点。针对棉花早衰的生理过程,通过采用植物生长调节剂,氮、钾、钙3种肥料,以及水分、光照、温度、气体等环境因子的调节措施来预防叶片早衰以及对出现叶片早衰后的稳产措施。最后对棉花叶片早衰的研究方向进行了展望。     

乙矮合剂对不同密度夏玉米花粒期叶片氮素同化与早衰的影响

为探讨乙矮合剂调控夏玉米氮素同化和防止后期早衰的生理机制,为建立华北夏玉米区密植高产稳产化学调控技术提供理论依据,2013—2014年在中国农业科学院新乡试验站,以中单909和浚单20为材料,设置乙矮合剂(ECK)和密度梯度处理,研究密度梯度对花后玉米穗位叶氮同化特征和早衰的影响,以及ECK的化学调控效应。结果表明,灌浆期(花后0~40 d),穗位叶硝酸还原酶(NR)活性和谷氨酰胺合成酶(GS)活性随密度增加而显著下降;灌浆后期(花后30~40 d),谷草转氨酶(GOT)和谷丙转氨酶(GPT)活性随种植密度增加而显著降低。穗位叶叶绿素相对含量、可溶性蛋白含量和游离氨基酸含量在灌浆中后期(花后20~40 d)随种植密度增加而显著降低;两品种产量在7.5万株hm–2密度达最大值,7.5~10.5万株hm–2密度群体产量下降,高密群体易发生早衰。ECK处理显著提高了各密度群体灌浆中后期(花后20~40 d)穗位叶NR活性、GS活性、游离氨基酸含量、可溶性蛋白含量和叶绿素含量;显著提高了高密群体(7.5~10.5万株hm–2)GOT活性和GPT活性;较高密群体下(7.5~10.5万株hm–2),中单909和浚单20较各自对照的增产幅度分别为5.59%~6.63%和6.73%~8.10%。ECK处理提高了高密群体夏玉米穗位叶片氮代谢关键酶活性及其产物含量,保证密植群体氮代谢正常进行,有效防止早衰及提高产量。综上所述,采用合理的种植密度并结合喷施乙矮合剂可作为华北夏玉米区高产栽培的重要技术措施。     

Dark induced senescence as a tool in breeding wheat for optimum senescence pattern

Senescence can influence: (1) leaf area duration, (2) area of transpiringtissue and (3) translocation of nutrients – mainly nitrogen to grain.Therefore, selection for optimum senescence pattern might be efficient forimproving performance of wheat in a given environment. This study wasconducted to investigate the feasibility of a seedling test for estimatinggenotypic differences in senescence rate of wheat. We studied the responseof several wheat genotypes to dark exposure of seedlings, by measuring therate of chlorophyll loss in the first leaf. The rate of chlorophyll loss variedsignificantly among genotypes, the highest rate being more than double ofthe lowest. Linear regression accounted for most of the chlorophyll contentvariation during dark treatment in all cultivars. Significant correlation wasfound between the rate of chlorophyll loss following exposure to darknessand chlorophyll loss during aging in an environment relatively free ofdiseases and stresses. A good correlation was also found between theresponse of several genotypes to dark exposure and chlorophyll loss ofseedlings following starvation. We conclude that a seedling test for darkinduced senescence might allow an easy characterization of senescencepattern, allowing increased genetic progress in its optimization.     

土壤深松对小麦根系活性的垂直分布及旗叶衰老的影响

土壤深松打破犁底层可改变土壤的理化性状 ,从而改善小麦根系的生长条件。与对照 (未深松 )相比 ,小麦的群体根系活性明显提高 ,垂直分布下移 ,使深层土壤的群体根系活性相对提高 ,进而对延缓地上部衰老和提高产量产生积极效应。     

免耕抛栽水稻源库特性研究

近些年来,水稻免耕抛秧栽培在中国广西等部分地区发展迅速。为了探讨免耕抛栽水稻产量形成特点,以金优253(OryzasativaL.)为试验材料,以常耕抛栽水稻为对照,从叶面积大小、剑叶光合速率与衰老、库的大小及源库比率等方面研究了免耕抛栽水稻的源库特性。结果表明,免耕抛栽水稻早、晚季产量分别为5.97t/hm2和7.53t/hm2,常耕抛栽水稻分别为6.19t/hm2和7.63t/hm2,其产量差异在早季和晚季均不显著。与常耕抛栽水稻相比,免耕抛栽水稻的每穗总粒数和单位面积上的总粒数较多,各生育期的叶面积指数较大,灌浆期剑叶光合速率、蒸腾速率、气孔导度、叶绿素含量较高,而过氧化物酶和过氧化氢酶活性及丙二醛的含量较低,在生理上存在一定的优势。但是,免耕抛栽水稻的源库协调能力较差,粒叶比和结实率下降,致使免耕抛栽水稻在产量上表现出一定的劣势。免耕抛栽水稻粒叶比和结实率的下降是由于其生产的干物质更多地分配在叶片中、贮藏在茎鞘中的干物质在抽穗后向穗部运转的能力较差造成的。     

水杨酸对黄花梨采后衰老和膜脂过氧化的影响

黄花梨果实采后用浓度为0.1 g/L,0.3 g/L的水杨酸(SA)溶液浸泡20 m in后,在(25±1)℃的贮藏条件下,研究了水杨酸处理对黄花梨果实采后衰老和膜脂过氧化的影响。结果表明,与以清水为对照相比,0.1 g/L SA处理能抑制SOD,CAT,POD活性的下降,降低果肉组织的相对电导率和MDA积累量,从而延缓了果实的成熟衰老;而0.3 g/L SA处理无明显影响。     

Paraquat Resistance in Leaf Discs of PAAG12-IPTModified Gerbera Is Related to the Activities of Superoxide Dismutase, Catalase, and Dehydroascorbate Reductase

In this paper, using in vitro leaf disc culture system, the changes of contents of chlorophylls, carotenoids, soluble protein, thiobarbituric acid reactive substance （TBARS）, and activities of antioxidant enzymes were investigated during the incubation of leaf discs of PSAG12-IPT modified gerbera in 0, 25, 50 μmol L^-1 paraquat （PQ） under continuous light intensity of 130 0tool m-2 s-1, compared with the control plant （wild type）. The results showed that PQ treatment significantly decreased the contents of chlorophylls, carotenoids, and soluble protein, therefore, promoted leaf senescence. However, the decreases in the leaf discs of modified gerbera were considerably smaller. The activities of superoxide dismutase （SOD）, catalase （CAT）, and dehydroascorbate reductase （DHAR） were significantly increased by PQ treatment and with the increasing of PQ concentration, particularly in the modified plants. The activities of ascorbate peroxidase （APX） and guaiacol peroxidase （GPX） could not be detected in the leaf discs of PQ treatments, which suggested that they were labile to the oxidative stress induced by PQ. As a product of lipid peroxidation, TBARS significantly increased in content with the increase of PQ concentration, while its concentration in the modified plants was significantly lower than that of control plants. Therefore, it could be concluded that the chimeric gene PSAG12-IPTtransfonnexi gerbera leaves had higher antioxidative potential, thus causing the delay of senescence under oxidative stress induced by PQ.