[Objective] The aim was to isolate the strains resistant to plant pathogenic fungi from Southern Ocean and study their phylogenetic relationship and antimicrobial spectrum. [Method] Agar diffusion method was adopted t...[Objective] The aim was to isolate the strains resistant to plant pathogenic fungi from Southern Ocean and study their phylogenetic relationship and antimicrobial spectrum. [Method] Agar diffusion method was adopted to screen antimicrobial strains and determine the antimicrobial spectrum. Phylogenetic relationship of the strains was analyzed by neighbor-joining method of the Mega 4.0 software. [Result] Twenty antimicrobial strains were screened from seawater of Southern Ocean collected during the 27^th Chinese Antarctic Scientific Expedition. Molecular identification and phyloge- netic analysis indicated that two antimicrobial strains were members of Pseu- domonas, two strains were members of Psychrobacter, and the other 16 trains were members of Pseudoalteromonas. The antimicrobial spectrum of four strains which had higher antimicrobial activity indicated that the strains 312, 83-1 and 195 greatly inhibited the growth of Fusarium oxysporum, Rhizoctonia solani K（Jhn, Phytophthora capsici Leonian, Verticillium dahliae, Alternaria solani, Thanatephoru scucumeris and Phomopsis asparagi （Sacc）; strain 312-1 had obvious antimicrobial effect on the six of the plant pathogens except R. solani. [Conclusion] Four strains which had higher antimicrobial effect were obtained and should be further studied for development and application.展开更多
Polar auxin transport (PAT) is critical in plant growth and development, especially polar differentiation and pattern formation. Lots of studies have been performed in dicots while relative less in monocots. Using two...Polar auxin transport (PAT) is critical in plant growth and development, especially polar differentiation and pattern formation. Lots of studies have been performed in dicots while relative less in monocots. Using two kinds of PAT inhibitors, 2, 3, 5-triiodobenzoic acid (TIBA) and 9-hydroxyfluorene-9-carboxylic acid (HFCA), it was shown that PAT is important for rice (Oryza sativa L. cv. Zhonghua 11) root development, including elongation of the primary roots, initiation and elongation of lateral roots, and formation of adventitious roots. Inhibition of PAT resulted in the shortened primary roots, less and shortened lateral and adventitious roots. Exogenously supplemented NAA can partially rescue the formation of adventitious roots but not lateral roots, while low concentration of NAA (0.1 mumol/L) could not rescue either of them, suggesting the possible different mechanisms of lateral and adventitious root initiations. Treatment of 30 mumol/L TIBA did not completely inhibit the initiation of lateral roots, and survival capacities of which were demonstrated through cross section experiments revealing the presence of primordial of lateral roots at different stages. Further studies through localized application of PAT inhibitors indicated that auxin flow, transported from coleoptiles to the base, is not only responsible for the auxin contents in stem nodes but also critical for initiation and elongation of adventitious roots.展开更多
The asymmetric leaves2 ( as2) is a classical Arabidopsis thaliana (L.) Heynh. mutant that shows leaf lobes and leaflet-like structures from the petioles of leaves. Genetic and molecular analyses have demonstrated that...The asymmetric leaves2 ( as2) is a classical Arabidopsis thaliana (L.) Heynh. mutant that shows leaf lobes and leaflet-like structures from the petioles of leaves. Genetic and molecular analyses have demonstrated that the AS2 function is required for repression of meristem-related homeobox genes in leaves. In this study, we describe phenotypic characterizations of new as2 alleles that are in the Landsberg erecta (Ler) genetic background. In addition to the as2 phenotypes reported previously, the new as2 mutants have some leaves with petiole growth underneath the leaf blade, showing a lotus-leaf structure. More severe rosettes leaves of the as2 mutants form a filament-like structure, reflecting a loss of the adaxial-abaxial polarity in leaves. Among as2 mutants analyzed in different genetic backgrounds, only those that are in the Ler genetic background resulted in a high frequency of the lotus-leaf structure. We have isolated the AS2 gene by map-based gene cloning. The predicted AS2 protein contains a leucine-zipper motif, and its N-terminus shares high levels of sequence similarity to those of a group of predicted proteins with no known biological functions. AS2 transcripts were detected in leaves, flowers and fruits, but absent in stems, consistent with the mutant phenotypes.展开更多
基金Supported by Public Science and Technology Research Projects of Ocean (201005032-2)~~
文摘[Objective] The aim was to isolate the strains resistant to plant pathogenic fungi from Southern Ocean and study their phylogenetic relationship and antimicrobial spectrum. [Method] Agar diffusion method was adopted to screen antimicrobial strains and determine the antimicrobial spectrum. Phylogenetic relationship of the strains was analyzed by neighbor-joining method of the Mega 4.0 software. [Result] Twenty antimicrobial strains were screened from seawater of Southern Ocean collected during the 27^th Chinese Antarctic Scientific Expedition. Molecular identification and phyloge- netic analysis indicated that two antimicrobial strains were members of Pseu- domonas, two strains were members of Psychrobacter, and the other 16 trains were members of Pseudoalteromonas. The antimicrobial spectrum of four strains which had higher antimicrobial activity indicated that the strains 312, 83-1 and 195 greatly inhibited the growth of Fusarium oxysporum, Rhizoctonia solani K（Jhn, Phytophthora capsici Leonian, Verticillium dahliae, Alternaria solani, Thanatephoru scucumeris and Phomopsis asparagi （Sacc）; strain 312-1 had obvious antimicrobial effect on the six of the plant pathogens except R. solani. [Conclusion] Four strains which had higher antimicrobial effect were obtained and should be further studied for development and application.
文摘Polar auxin transport (PAT) is critical in plant growth and development, especially polar differentiation and pattern formation. Lots of studies have been performed in dicots while relative less in monocots. Using two kinds of PAT inhibitors, 2, 3, 5-triiodobenzoic acid (TIBA) and 9-hydroxyfluorene-9-carboxylic acid (HFCA), it was shown that PAT is important for rice (Oryza sativa L. cv. Zhonghua 11) root development, including elongation of the primary roots, initiation and elongation of lateral roots, and formation of adventitious roots. Inhibition of PAT resulted in the shortened primary roots, less and shortened lateral and adventitious roots. Exogenously supplemented NAA can partially rescue the formation of adventitious roots but not lateral roots, while low concentration of NAA (0.1 mumol/L) could not rescue either of them, suggesting the possible different mechanisms of lateral and adventitious root initiations. Treatment of 30 mumol/L TIBA did not completely inhibit the initiation of lateral roots, and survival capacities of which were demonstrated through cross section experiments revealing the presence of primordial of lateral roots at different stages. Further studies through localized application of PAT inhibitors indicated that auxin flow, transported from coleoptiles to the base, is not only responsible for the auxin contents in stem nodes but also critical for initiation and elongation of adventitious roots.
文摘The asymmetric leaves2 ( as2) is a classical Arabidopsis thaliana (L.) Heynh. mutant that shows leaf lobes and leaflet-like structures from the petioles of leaves. Genetic and molecular analyses have demonstrated that the AS2 function is required for repression of meristem-related homeobox genes in leaves. In this study, we describe phenotypic characterizations of new as2 alleles that are in the Landsberg erecta (Ler) genetic background. In addition to the as2 phenotypes reported previously, the new as2 mutants have some leaves with petiole growth underneath the leaf blade, showing a lotus-leaf structure. More severe rosettes leaves of the as2 mutants form a filament-like structure, reflecting a loss of the adaxial-abaxial polarity in leaves. Among as2 mutants analyzed in different genetic backgrounds, only those that are in the Ler genetic background resulted in a high frequency of the lotus-leaf structure. We have isolated the AS2 gene by map-based gene cloning. The predicted AS2 protein contains a leucine-zipper motif, and its N-terminus shares high levels of sequence similarity to those of a group of predicted proteins with no known biological functions. AS2 transcripts were detected in leaves, flowers and fruits, but absent in stems, consistent with the mutant phenotypes.
