| Cell wall is one of the most remarkably characteristics of plant cell. The main function of cell wall may involve to ensure plant cell modality, protect plant cell and accept signals of environment. Plant cell wall proteins can be classified two classes: cell wall structural protein and cell wall related enzymes. At present, there are five main classes cell wall structural protein that rich present in all kinds of plant cell walls were often investigated. They are named extensin or hydroxyproline-rich glycoprotein(HRGP) , glycine-rich proteins(GRPs) , arabinogalactan proteins (AGPs) , solanaceous lectins and proline-rich proteins (PRPs),respectively. Proline-rich proteins (PRPs) that were initially identified as wound-induced gene products in carrot storage roots.These proteins have been shown to be expressed in many plant species in a manner that is temporally and spatially regulated during plant development.The expression of PRPs is also influenced by factors associated with pathogen infection or environmental stresses such as elicitor treatment and wounding. PRPs may function both in determining cell-type-specific wall structure during plant development and by contributing to defense reactions against physical damage and pathogen infection. In our studies, we isolated five proline-rich cell wall protein genes in cotton by screening cotton cDNA library according to sequence homologous analysis. We named them as GhPRP3, GhPRP4 , GhPRP5,, GhPRP6 , GhPRP11,respectively. The GhPRP3, GhPRP4, GhPRP5 , GhPRP6 , GhPRP11 contained 369bp, 408bp, 582bp, 876bp, 648bp open reading frames(ORF) encoding the protein of 122, 135 , 193, 291 , 215 amino acidses, respectively. It has important theoretics significance and application value to separate and characterise the function of these genes and clear up their expression and regulation, related to growths of cotton fibers which selected from the cotton cDNA library in our lab. Our experiments from below several aspects to study these five genes functions.1. Sequence analysisThe five GhPRPs possess signal-peptide sequences and transmembrane regions in their N-end from l-25aa and 9-30aa, respectively. We analysed the five GhPRP primarily structure,the results showed that the five proteins possess proline residues 10.6%, 10.3%, 18.0%, 24.4%, 34.9%,respectively. They also contain many Protein kinase C phosphorylation sites and several N-myristoylation sites. So,we prodicted these proteins maybe exist as signal moleculars that receive enviromental signal in cell wall.Sequence identity analysis showed GhPRP3-5 amino acid sequence contain 8CM regions (eight-cysteine motif) . GhPRP3-5 displayed a considerable degree of sequence identity (30-70%) with other plant proline-rich cell wall glycoproteins. GhPRP possess pollen Ole e 1 allergen and extensin family protein region,display a comparative high sequence identity with AtPRP, CaPRP1, NtPRP4, DcAGP1, PvPRP1. GhPRP11 display a comparative highly sequence identity with AtPRP9 and MsPRP1.2. Primary analysis expression of geneCotton total RNA was isolated from different tissures of cotton , different developmental period of cotton fiber and ouvle by hot-phenolic mothed. We primarily make use of RT-PCR methods to analysis the expression of GhPRP3 , GhPRP4 , GhPRP5 and GhPRP6 genes. Then utilized northern hybridization analysis these genes expression pattern. The results of RT-PCR are accordance with RNA gel-blot analysis. Northern hybridization experimental results showed that the GhPRP3 gene is expressed specific only in cotton leaf and petal. But the expression of GhPRP3 in cotton leaf is higher than petal. The result showed GhPRP3 is leaf and petal specific expression. GhPRP4 was preferential express in cotton petal, showed GhPRP4 gene expression is petal-specific. The gene also express in cotton root, cotyledon, hypocotyl, 10 DPA ovule, 15 DPA ovule, and express in 10 DPA ovule slightly lower than petal. GhPRP5 was preferential express in cotton petal, The gene al...
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