Characterization Of Rice Rho GTPase Activating Protein Encoding Gene OsRhoGAP1

Rice OsRhoGAP1and OsRhoGAP2are rice OsRacD interacting protein coding genes screened by theyeast two-hybrid. Preliminary studies suggest, OsRacD may be involved in rice fertility regulation. In orderto study the role of OsRhoGAP1in rice growth, the sequence features of these two OsRhoGAPs genes andtheir expression characteristics were analyzed and compared at different developmental stages of rice, therelationship between the expression of OsRhoGAP1and exogenous plant hormones were further analyzed,its promoter were forecasted and analyzed, OsRhoGAP1plant overexpression vector were constructed andtransformed it into rice, the positive transgenic plants were screened for in-depth study of the function andregulation of OsRhoGAP1.Sequence characteristics of OsRhoGAP1and OsRhoGAP2were analyzed and compared throughbioinformatics methods. Blast in rice genome database showed that OsRhoGAP1and OsRhoGAP2werelocated on the12th and2nd chromosome respectively. The two genes had similar gene structure containing5exons and4introns. OsRhoGAP1had a1353bp cDNA coding region, encoding450amino acids and astop codon, OsRhoGAP2had a1320bp cDNA coding region, encoding439amino acids and a stop codon.The two proteins both possesed plant RhoGAP/RopGAP conserved protein features that containined twoconserved domains of RhoGAP and CRIB, but their large differences lay in the N-terminal and C-terminalsequences. Phylogenetic analysis showed that, OsRhoGAP1shared highest similarity with riceOsRacGAP3, OsRhoGAP2shared highest similarity with ZmRacGAP2from corn.The expression characteristics of OsRhoGAP1and OsRhoGAP2at different developmental stages ofrice were studied by real-time PCR. the results showed that these two genes expressed widely in rice, andthey both highly expressed in actively dividing cells such as young leaves, young panicles, young roots aswell as mature roots, suggesting that they may be involved in rice growth, development and differentiation.However, the expression levels of OsRhoGAP1and OsRhoGAP2at specific developmental stages weredifferent, suggesting that they may each have unique functions.Search and forecast showed, OsRhoGAP1promoter contained elements of light, plant hormones,abiotic stress responses. To determine the influence of plant hormone on OsRhoGAP1expression, the expression levels of the gene under6plant hormones were tested by real-time PCR. The results showed,ABA, SA, MeJA up-regulated OsRhoGAP1expression by3to4.1times first and then down-regulated it,GA up-regulated it sharply by6.4times, while the IAA and6-BA made it rapidly down to0.2~0.3times,suggesting that the expression of OsRhoGAP1is regulated by a variety of plant hormone signals, especiallyGA, IAA and6-BA signals.In order to identify the function of OsRhoGAP1through transgenic technology, OsRhoGAP1geneplant overexpression vector fused with GFP was constructed by recombinant DNA techniques, thentransformed into rice by agrobacterium-mediated method, the screening and identification of T0transgenicrice is performing now.In this study, a series of studies of rice OsRhoGAP1provided important information to explore the roleof this gene in rice growth and development as well as plant hormone signaling responses, and contributedto in-depth study of OsRhoGAPs function and their regulation of Rop.