Study On The Mechanism Of Loose Plant Architecture 1 Regulating Resistance To Rice Sheath Blight

Sheath blight is one of the serious diseases in rice cultivation,distributed in various rice cultivating regions wordwide.The disease has occurred from the seedling stage to the booting stage.Sheath blight is most prevalent around the heading stage.It will cause a huge loss of rice yield production.So far,the mechanism of rice resistance to sheath blight disease is still unclear,and the lack resistant genes and highly resistant lines.Therefore,it is important to study the mechanism of resistance to sheath blight disease.The Ds insertion mutants were used to screen out the lpa1 mutant that is more suceptible to Rhizoctonia solani in our previous study.Therfore,we took LPA1 as the research object and obtained the following results through further research:1.LPA1 positively regulates rice resistance to sheath blightWild-type rice was inoculated with Rhizoctonia solani AG1-IA at 0,24,48 and 72 hours,and the expression level of LPA1 was detected by q RT-PCR.The expression of LPA1 was significantly up-regulated by the inoculaition of R.solani AG1-IA after 72 hours.The lpa1 mutant and revertant were inoculated with R.solani AG1-IA,and the resistance identification was performed.The results showed that the lpa1 mutant was more susceptible to disease than the wild-type control and revertant.Compared to the wild type control,LPA1 overexpression plants were less susceptible to disease.At the same time,the expression levels of pathogenesis-related gene PBZ1 and PR1 b in LPA1 overexpression plants were examined.The expression levels of the resistance genes PBZ1 and PR1 b were up-regulated in LPA1 overexpression plants.These results indicate that LPA1 positively regulates resistance to sheath blight.2.LPA1 binds to the PIN1 a promoter sequencesPrevious studies have shown that auxin plays an important role in disease resistance.PIN1 a is involved in the auxin transport process,and LPA1 regulates the transcription of PIN1 a.Further results confirmed that overexpression of LPA1 increased the expression of PIN1 a.Ch IP,EMSA and transient expression results show that LPA1 is able to bind to the PIN1 a promoter to activate its transcription.3.LPA1 regulates rice resistance to sheath blight by regulating PIN1 a transcriptionIn order to verify the role of PIN1 a in resistance to sheath blight,PIN1 a RNAi and PIN1 a overexpression plants were inoculated with R.solani AG1-IA.The results showed that compared with WT,the PIN1 a level in PIN1 a RNAi was significantly reduced,and the PIN1 a RNAi line was more susceptible to inoculation with R.solani AG1-IA,while the PIN1 a level in was significantly higher in the PIN1 a overexpression plants,and PIN1 a overexpression plants were less susceptible to the disease.These results proved that PIN1 a positively regulates rice resistance to sheath blight.4.Effect of auxin on resistance to sheath blight diseaseAuxin plays an important role in disease resistance.PIN1 a is an auxin efflux carrier,and LPA1 may affect the auxin distribution in plants by regulating the expression of PIN1 a,thereby regulating rice resistance to sheath blight.We found that exogenously treated auxin enhanced rice resistance to sheath blight,and LPA1 overexpression increased IAA contents in rice leaves.In summary,these results indicate that LPA1 may regulate the transport of auxin in rice by regulating PIN1 a,thereby enhancing rice resistance to sheath blight.