Using plant mini-Ti cosmid pEND4K, the cosmid genomic library of Sesbania rostratawas constructed. Sizes of plant DNA inserts in clones were 25- 33 kb. The restrictionmapping showed that different recombinant involved...Using plant mini-Ti cosmid pEND4K, the cosmid genomic library of Sesbania rostratawas constructed. Sizes of plant DNA inserts in clones were 25- 33 kb. The restrictionmapping showed that different recombinant involved various types of plant DNA insert. 4clones containing leghemoglobin gene sequence of S. rostrata were obtained by in situ hy-bridization of colonies. The cloning of leghemoglobin gene sequence has been confirmedby plasmid DNA dot hybridization and Southern blot hybridization.展开更多
LegHb mRNAs isolated from 2 to 10-week old alfalfa nodules are actively translated in vitro to give a full component of legHb products suggesting that legHb genes, once expressed, are not regulated at the transcriptio...LegHb mRNAs isolated from 2 to 10-week old alfalfa nodules are actively translated in vitro to give a full component of legHb products suggesting that legHb genes, once expressed, are not regulated at the transcription level during the lifetime of a nodule. In vitro translation studies with legHb mRNAs from 10-week old nodules indicate that translation of mRNAs is partially inhibited by addition of alfalfa legHb components themselves and is not promoted by addition of myoglobin and hemoglobin as compared with those of alfalfa legHb mRNAs isolated from 4-week old nodules. This intimates that the regulation of alfalfa legHb synthesis in old nodules at the translation level is weakened.展开更多
【目的】探索咪唑乙烟酸抑制大豆根瘤固氮酶活性的关键机制,为解决咪唑乙烟酸长期大量应用对根瘤固氮的毒害提供依据。【方法】采用田间试验方法,研究咪唑乙烟酸茎叶处理对根瘤固氮酶活性的影响与根瘤豆血红蛋白含量、根瘤类菌体和细胞...【目的】探索咪唑乙烟酸抑制大豆根瘤固氮酶活性的关键机制,为解决咪唑乙烟酸长期大量应用对根瘤固氮的毒害提供依据。【方法】采用田间试验方法,研究咪唑乙烟酸茎叶处理对根瘤固氮酶活性的影响与根瘤豆血红蛋白含量、根瘤类菌体和细胞浆中氨含量的关系。【结果】咪唑乙烟酸施用后21 d内,固氮酶活性受到显著抑制。112.5和225.0 g a.i./hm2施药量下,对豆血红蛋白含量的抑制峰值分别出现在第7、14天,抑制率分别为30.52%和35.41%,抑制作用分别在第21、28天得到解除。根瘤类菌体中氨含量抑制峰值均出现在第14天,抑制率分别为35.33%和48.96%,第28天氨含量均恢复正常。细胞浆中氨含量显著增高,且分别在第21、28天恢复正常。【结论】咪唑乙烟酸茎叶处理后,豆血红蛋白含量降低是导致固氮酶活性降低的1个重要原因,同时细胞浆中氨积累也造成了对固氮酶活性的反馈抑制。展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Using plant mini-Ti cosmid pEND4K, the cosmid genomic library of Sesbania rostratawas constructed. Sizes of plant DNA inserts in clones were 25- 33 kb. The restrictionmapping showed that different recombinant involved various types of plant DNA insert. 4clones containing leghemoglobin gene sequence of S. rostrata were obtained by in situ hy-bridization of colonies. The cloning of leghemoglobin gene sequence has been confirmedby plasmid DNA dot hybridization and Southern blot hybridization.
文摘LegHb mRNAs isolated from 2 to 10-week old alfalfa nodules are actively translated in vitro to give a full component of legHb products suggesting that legHb genes, once expressed, are not regulated at the transcription level during the lifetime of a nodule. In vitro translation studies with legHb mRNAs from 10-week old nodules indicate that translation of mRNAs is partially inhibited by addition of alfalfa legHb components themselves and is not promoted by addition of myoglobin and hemoglobin as compared with those of alfalfa legHb mRNAs isolated from 4-week old nodules. This intimates that the regulation of alfalfa legHb synthesis in old nodules at the translation level is weakened.
文摘【目的】探索咪唑乙烟酸抑制大豆根瘤固氮酶活性的关键机制,为解决咪唑乙烟酸长期大量应用对根瘤固氮的毒害提供依据。【方法】采用田间试验方法,研究咪唑乙烟酸茎叶处理对根瘤固氮酶活性的影响与根瘤豆血红蛋白含量、根瘤类菌体和细胞浆中氨含量的关系。【结果】咪唑乙烟酸施用后21 d内,固氮酶活性受到显著抑制。112.5和225.0 g a.i./hm2施药量下,对豆血红蛋白含量的抑制峰值分别出现在第7、14天,抑制率分别为30.52%和35.41%,抑制作用分别在第21、28天得到解除。根瘤类菌体中氨含量抑制峰值均出现在第14天,抑制率分别为35.33%和48.96%,第28天氨含量均恢复正常。细胞浆中氨含量显著增高,且分别在第21、28天恢复正常。【结论】咪唑乙烟酸茎叶处理后,豆血红蛋白含量降低是导致固氮酶活性降低的1个重要原因,同时细胞浆中氨积累也造成了对固氮酶活性的反馈抑制。
