Use Of Ospgip Gene In Rice Breeding Against Sheath Blight

Polygalacturonase-inhibiting protein (PGIP) are structural proteins of plant cell wall that specifically bind to and inhibit fungal polygalacturonases (PG), therefore probably playing an important role in plant resistance to fungal diseases. In this study,the results were summarized as follows:1. The gene Ospgipl contains a complete ORF of930bp but no introns. The gene was cloned into pCMBIA1301to yield an over-expression vector which was then introduced into the rice cultivar Xudao3(Japonica) by AMT. The expression of the gene in transgenic lines was confirmed by RT-PCR. Transgenic plants were cultivated in paddy field to test their resistance to sheath blight. The paddy field experiments demonstrated that the disease severity of the transgenic plants decreased1.0to1.2(9-Level Classification Standard). The survey on agronomic traits showed that there were no significant differences between the transgenic plants and their parents.2The gene Ospgip2has a complete ORF of930bp and encods a putative protein (OsPGIP2) of342amino acids with10LRRs. The point mutations were made in OsPGIP2LRR domain which has no inhibitory activity to PG of R.solani. Through E. coli expression system, the mutants that showed PG inhibition activity were selected and were introduced into rice to obtain the transgenic rice lines with improved resistance to sheath blight.Three amino acids of OsPGIP2LRR regions were independently mutated to yield the respective mutants OsPGIP2L233F, OsPGIP2R253Q and OsPGIP2Q300H. The results of prokaryotic expression of these proteins using E. coli BL21showed that a single substitution, L233F, caused OsPGIP2to gain the ability to bind with the PG of R.solani. The inhibition activity was876U/mL. The vector containg Ospgip2L233F was transferred into rice as did for Ospgipl using AMT method. The study on the seedling resistance to sheath blight indicated that rice transgenic seedlings obtained increased sheath blight resistanc.