To understand the expansion ofmulticopy microRNA （miRNA） families in plants, we localized the reported miRNA genes from Arabidopsis and rice to their chromosomes, respectively, and observed that 37% of 117 miRNA gen...To understand the expansion ofmulticopy microRNA （miRNA） families in plants, we localized the reported miRNA genes from Arabidopsis and rice to their chromosomes, respectively, and observed that 37% of 117 miRNA genes from Arabidopsis and 35% of 173 miRNA genes from rice were segmental duplications in the genome. In order to characterize whether the expression diversification has occurred among plant multicopy miRNA family members, we designed PCR primers targeting 48 predicted miRNA precursors from 10 families in Arabidopsis and rice. Results from RT-PCR data suggest that the transcribed precursors of members within the same miRNA family were present at different expression levels. In addition, although miRl60 and miR162 sequences were conserved in Arabidopsis and rice, we found that the expression patterns of these genes differed between the two species. These data suggested that expression diversification has occurred in multicopy miRNA families, increasing our understanding of the expression regulation of miRNAs in plants.展开更多
Using luc gene as a reporter to study the activation of Rhizobium meliloti nif/fix genes in thedevelopment of symbiosis,the authors observed that nodule development and nitrogen fixation were inhibitedby both multicop...Using luc gene as a reporter to study the activation of Rhizobium meliloti nif/fix genes in thedevelopment of symbiosis,the authors observed that nodule development and nitrogen fixation were inhibitedby both multicopy promoters of nifHDK and fixABCX.The phenotype of R.meliloti containing multicopynif/fix promoters appeared exactly like that of nifA mutant.Using lacZ as a reporter,the authors got the same re-sults.By contrast,the rhizobia containing low-copy promoters of nif/fix genes were normal fornodule development and nitrogen fixation.These results substantiate the evidence that the product of nifAgene not only acts as a transcriptional activator of nif/fix genes,but also plays an important role in thedevelopment of root nodules.展开更多
基金We acknowledge Prof HerváVaucheret for kindly supplying the agol-27 mutant and Dr Xuemei Chen for helpful suggestions and reviewing this manuscript.This work was supported by the Fund of National Key Basic Research Developments Program of the Ministry of Science and Technology China(2001CB109002)National Natural Science Foundation of China(30370893)+2 种基金Shanghai Municipal Committee of Science and Technology(03JC14061)the Program for New Century Excellent Talents in University(NCET-04-0403)the ShuGuang Scholarship(04SG15).
文摘To understand the expansion ofmulticopy microRNA （miRNA） families in plants, we localized the reported miRNA genes from Arabidopsis and rice to their chromosomes, respectively, and observed that 37% of 117 miRNA genes from Arabidopsis and 35% of 173 miRNA genes from rice were segmental duplications in the genome. In order to characterize whether the expression diversification has occurred among plant multicopy miRNA family members, we designed PCR primers targeting 48 predicted miRNA precursors from 10 families in Arabidopsis and rice. Results from RT-PCR data suggest that the transcribed precursors of members within the same miRNA family were present at different expression levels. In addition, although miRl60 and miR162 sequences were conserved in Arabidopsis and rice, we found that the expression patterns of these genes differed between the two species. These data suggested that expression diversification has occurred in multicopy miRNA families, increasing our understanding of the expression regulation of miRNAs in plants.
基金the National Natural Science Foundation of China.
文摘Using luc gene as a reporter to study the activation of Rhizobium meliloti nif/fix genes in thedevelopment of symbiosis,the authors observed that nodule development and nitrogen fixation were inhibitedby both multicopy promoters of nifHDK and fixABCX.The phenotype of R.meliloti containing multicopynif/fix promoters appeared exactly like that of nifA mutant.Using lacZ as a reporter,the authors got the same re-sults.By contrast,the rhizobia containing low-copy promoters of nif/fix genes were normal fornodule development and nitrogen fixation.These results substantiate the evidence that the product of nifAgene not only acts as a transcriptional activator of nif/fix genes,but also plays an important role in thedevelopment of root nodules.
