Leaf cells undergo two main developmental events;i.e., cell proliferation and cell differentiation, before maturation. These events occur sequentially at specific positions and with specific timing during leaf develop...Leaf cells undergo two main developmental events;i.e., cell proliferation and cell differentiation, before maturation. These events occur sequentially at specific positions and with specific timing during leaf development. To understand the transition from cell proliferation to cell differentiation of rice leaves, we analyzed rice leaves from both morphological and molecular viewpoints. The results of anatomical, morphological, and histochemical analyses indicated that P4 leaf primordium is the stage when dynamic transition of the cellular state from immature to mature along the proximal-distal axis of the leaf occurs. We screened for marker genes showing a dynamic expression pattern along the proximal-distal axis of the P4 leaf, and applied them to expression analysis in wild-type and various morphogenetic mutants. The changes in expression pattern of the marker genes varied between developmental stages and between mutants. Our analysis reinforced previous data regarding the developmental transition of wild-type rice leaves and indicated that the transition can be monitored using our molecular markers. The results of this study indicate that expression analysis using these molecular markers would be valuable for understanding the genetic effects on leaf development in various leaf morphogenetic mutants.展开更多
Abstract: A rice mutant with reduced heading date (designated rhd1) found in a transgenic line of cultivar Teqing 2 (Oryza sativa L. ssp. indica) was used to identify the genes related to rice heading and thereby to s...Abstract: A rice mutant with reduced heading date (designated rhd1) found in a transgenic line of cultivar Teqing 2 (Oryza sativa L. ssp. indica) was used to identify the genes related to rice heading and thereby to study its molecular mechanism. Genetic analysis showed that rhd1 was a dominant mutation and did not result from T-DNA insertion. By using the differential display polymerase chain reaction (DD-PCR) technique, differential gene expression between rhd1 and Teqing 2 was compared and a rhd1-down-regulated c DNA fragment was identified. Sequence analysis showed that this fragment shared 99% similarity to the OsGRF1 (O. sativa growth-regulating factor 1) gene. The OsGRF1 gene encodes a putative transcription factor, which contains two conserved regions: the QLQ (Gln, Leu, Gln) and WRC (Trp, Arg, Cys) domains. Southern analysis indicates that OsGRF1 may be encoded by single copy gene in the rice genome. RNA interference results revealed that transgenic lines with reduced OsGRF1 transcript displayed delayed growth and development, developed small leaves, and had delayed heading. The extent of the phenotypes developed was well-correlated with the OsGRF1 gene transcript. Our results clearly demonstrate that the OsGRF1 gene is not only involved in regulating growth at the juvenile stage, but that it may also be involved in the regulation of heading in rice.展开更多
文摘Leaf cells undergo two main developmental events;i.e., cell proliferation and cell differentiation, before maturation. These events occur sequentially at specific positions and with specific timing during leaf development. To understand the transition from cell proliferation to cell differentiation of rice leaves, we analyzed rice leaves from both morphological and molecular viewpoints. The results of anatomical, morphological, and histochemical analyses indicated that P4 leaf primordium is the stage when dynamic transition of the cellular state from immature to mature along the proximal-distal axis of the leaf occurs. We screened for marker genes showing a dynamic expression pattern along the proximal-distal axis of the P4 leaf, and applied them to expression analysis in wild-type and various morphogenetic mutants. The changes in expression pattern of the marker genes varied between developmental stages and between mutants. Our analysis reinforced previous data regarding the developmental transition of wild-type rice leaves and indicated that the transition can be monitored using our molecular markers. The results of this study indicate that expression analysis using these molecular markers would be valuable for understanding the genetic effects on leaf development in various leaf morphogenetic mutants.
文摘Abstract: A rice mutant with reduced heading date (designated rhd1) found in a transgenic line of cultivar Teqing 2 (Oryza sativa L. ssp. indica) was used to identify the genes related to rice heading and thereby to study its molecular mechanism. Genetic analysis showed that rhd1 was a dominant mutation and did not result from T-DNA insertion. By using the differential display polymerase chain reaction (DD-PCR) technique, differential gene expression between rhd1 and Teqing 2 was compared and a rhd1-down-regulated c DNA fragment was identified. Sequence analysis showed that this fragment shared 99% similarity to the OsGRF1 (O. sativa growth-regulating factor 1) gene. The OsGRF1 gene encodes a putative transcription factor, which contains two conserved regions: the QLQ (Gln, Leu, Gln) and WRC (Trp, Arg, Cys) domains. Southern analysis indicates that OsGRF1 may be encoded by single copy gene in the rice genome. RNA interference results revealed that transgenic lines with reduced OsGRF1 transcript displayed delayed growth and development, developed small leaves, and had delayed heading. The extent of the phenotypes developed was well-correlated with the OsGRF1 gene transcript. Our results clearly demonstrate that the OsGRF1 gene is not only involved in regulating growth at the juvenile stage, but that it may also be involved in the regulation of heading in rice.
