Research On Function Of OsABCB11 Gene In Rice

As one of the three auxin transporter families,plant ABCB transporters play important roles in plant growth and development.However,there are few reports about the functions of the ABCB protein family in monocotyledonous plants,especially in rice.It is important to explore the functions of ABCB protein to further reveal the auxin signaling pathway and their roles in growth and development.OsABCB11 is a member of the rice ABCB family and its function has not been reported.Sequence analysis showed that there is multiple hormone response elements and stress response elements in OsABCB11 promoter,and the transient treatment further proved that OsABCB11 gene is induced by IAA,PEG and NaCl,suggesting that OsABCB11 may play a role in auxin and stress response pathways.In this study,OsABCB11 is located on the plasma membrane by transient infection in tobacco and rice protoplast transformation experiments,using an expression vector with OsABCB11-eGFP fusion proteins.Through RT-qPCR analysis of the spatiotemporal expression pattern of OsABCB11,we found that OsABCB11 is constitutively expressed in rice at all stages,and the expression level is higher in the stem,root-stem transition,young panicle and internode.In order to further explore OsABCB11 role in the growth of rice,two overexpression lines(11OE-01 and 11OE-02)and two gene knockout lines(11-cr-12,11-cr-34)were constructed through transgenic technology.Agronomic traits observed in OsABCB11 overexpressing lines showed that grain length,tillering angle,total tillers and effective tillers number was increased.The photosynthetic measurement results revealed that the net photosynthetic rate of OsABCB11 overexpressing lines was higher than that of wild-type rice under normal growth conditions;the expression levels of OsIAA20,OsPIN1 a and OsPIN1 b in OsABCB11 overexpression lines were down-regulated by RT-qPCR analysis.In addition,the expression levels of OsLazy1 and OsLPA1,which negatively regulate the tillering angle of rice,were also down-regulated.These results suggest that OsABCB11 positively regulates rice tillering angle might through regulating expression of auxin signaling genes.This study provides a new insight for illuminating biologicalfunctions of ABCB family and increases gene resources of controlling rice architecture.