Expression, Cloning And Genetic Transformation Of Receptor-like Protein Genes In Rice And Cotton

Receptor-like proteins (RLPs) belong to one kind of receptor-like protein in plants. RLPs play an important role in mediating the signal transductions of senescence and the abiotic stresses. Update, it is still in lack of a thoroughly elucidation for the RLPs in rice. In this study, in total 41 RLP genes of rice were identified by searching the rice genome sequences which were released in the GenBank. Based on the approaches of modern molecular biology and bioinformatics, the gene structures of the rice RLP genes, the expression patterns of the rice RLP genes under normal growth (CK) and treatment of 6-BA, and ABA has been analyzed. The functions of several tested rice RLP genes were also studied. In the meantime, several RLP genes in cotton which are homologous to the corresponding ones in rice have been cloned. The main results were as follows:1. There were huge differences on the structure properties among the rice RLP genes. The DNA length, cDNA full length, open reading frame length, and the translated amino acid numbers among the rice RLP genes were dramatically diverse. The rice 41 RLP genes have high consistency in the origin and evolution based on phylogenetic tree analysis. However, part genes of them are variable on the gene structure characteristics.2. Under normal growth (CK) and 6-BA, ABA treatment, no transcripts of OsRLP34 gene were detected. The expression of OsRLP06 was specifically up-regulated in leaves under natural aging and 6-BA, ABA treatment. The expressions of OsRLP03, OsRLP37, OsRLP58, OsRLP59 and OsRLP65 were specifically up-regulated in leaves with the leaf natural aging progression. Meanwhile, the time-course changes of the transcripts of OsRLP03, OsRLP37, OsRLP58, OsRLP59 and OsRLP65 were shown to be a curve with a one peak, at the time point of 10 d after 6-BA treatment. OsRLP03, OsRLP37, OsRLP58, OsRLP59 and OsRLP65 were specifically up-regulated in leaves under ABA treatment, but OsRLP03 and OsRLP37 were specifically down-regulated in leaves after 10d treatment. The expressions of OsRLP03, OsRLP37, OsRLP58, OsRLP59 and OsRLP65 under 6-BA treatment were same as that of ABA treatment.3. It is found that the OsRLP65 promoter could drive the Gus to be transcribed at a high level. Totally 34 cis-regulatory elements were identified in the full promoter. Among them, some of cis-regulatory elements play an important role in mediating the abiotic stresses signallings.4. Based on the transgenic tobacco plants of genetic transformation OsRLP65 promoter, the functions of this promoter on driving the target gene expression, has been evuluated. It is found that the promoter of OsRLP65 and its deleted fragments could drive the Gus to be transcribed, with an increase pattern with the prolong of the promoter segments. D1 (246 bp) promoter could drive the Gus gene to be transcribed at a little level, D5 (1427bp) promoter could drive the Gus gene to be transcribed at high level same as that of the full length of OsRLP65 promoter.5. Under natural growth condition, the senescence tolerance in the transgenic lines with high expression of antisense GhRLP6 and OsRLP65 was obviously improved compared with the control (CK). Meanwhile, the malonaldehyde (MDA) contents were lower in the transgenic lines, and the contents of chlorophyll a, chlorophyll b, carotenoid, and soluble protein were all higher. Taken together, the cellular protection metabolic pathway was response to the senescence signal transduction mediated by antisense GhRLP6 and OsRLP65.