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
Mycorrhizal fungi promote the growth and development of plants, including medicinal plants. The mechanisms by which this growth promotion occurs are of theoretical interest and practical importance to agriculture. Her...Mycorrhizal fungi promote the growth and development of plants, including medicinal plants. The mechanisms by which this growth promotion occurs are of theoretical interest and practical importance to agriculture. Here, an endophytic fungus （AR-18） was isolated from roots of the orchid Anoectochilus roxburghii growing in the wild, and identified as Epulorhiza sp. Tissue-cultured seedlings of A. roxburghii were inoculated with AR-l 8 and co-cultured for 60 d. Endotrophic mycorrhiza formed and the growth of A. roxburghii was markedly promoted by the fungus. To identify genes in A. roxburghii that were differentially expressed during the symbiosis with AR-18, we used the differential display reverse transcription polymerase chain reac- tion （DDRT-PCR） method to compare the transcriptomes between seedlings inoculated with the fungus and control seedlings. We amplified 52 DDRT-PCR bands using 15 primer combinations of three anchor primers and five arbitrary primers, and nine bands were re-amplified by double primers. Reverse Northern blot analyses were used to further screen the bands. Five clones were up-regulated in the symbiotic interaction, including genes encoding a uracil phosphoribosyltransferase （UPRTs; EC 2.4.2.9） and a hypothetical protein. One gene encoding an amino acid transmembrane transporter was down-regulated, and one gene encoding a tRNA-Lys （trnK） and a maturase K （matK） pseudogene were expressed only in the inoculated seedlings. The possible roles of the above genes, especially the UPRTs and marK genes, are discussed in relation to the fungal interaction. This study is the first of its type in A. roxburghii.展开更多
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.
基金supported by the National Natural Science Foundation of China (Grant Nos. 31070300, 31170314 and 31100265)the Chinese Postdoctoral Science Fund (Grant No. 20080440328)+1 种基金the Natural Science Foundation of Chongqing (Grant No. CSTC2008BB5410)the Educational Committee Science & Technology Foundation of Chongqing (Grant No. KJ090504)
文摘Mycorrhizal fungi promote the growth and development of plants, including medicinal plants. The mechanisms by which this growth promotion occurs are of theoretical interest and practical importance to agriculture. Here, an endophytic fungus （AR-18） was isolated from roots of the orchid Anoectochilus roxburghii growing in the wild, and identified as Epulorhiza sp. Tissue-cultured seedlings of A. roxburghii were inoculated with AR-l 8 and co-cultured for 60 d. Endotrophic mycorrhiza formed and the growth of A. roxburghii was markedly promoted by the fungus. To identify genes in A. roxburghii that were differentially expressed during the symbiosis with AR-18, we used the differential display reverse transcription polymerase chain reac- tion （DDRT-PCR） method to compare the transcriptomes between seedlings inoculated with the fungus and control seedlings. We amplified 52 DDRT-PCR bands using 15 primer combinations of three anchor primers and five arbitrary primers, and nine bands were re-amplified by double primers. Reverse Northern blot analyses were used to further screen the bands. Five clones were up-regulated in the symbiotic interaction, including genes encoding a uracil phosphoribosyltransferase （UPRTs; EC 2.4.2.9） and a hypothetical protein. One gene encoding an amino acid transmembrane transporter was down-regulated, and one gene encoding a tRNA-Lys （trnK） and a maturase K （matK） pseudogene were expressed only in the inoculated seedlings. The possible roles of the above genes, especially the UPRTs and marK genes, are discussed in relation to the fungal interaction. This study is the first of its type in A. roxburghii.
