Osa-miR535,Osa-miR160a And Other Three MiRNAs Regulate The Resistance To Rice Blast And The Agronomic Traits Of Rice

Rice is one of the most important food in world.More than half of the world’s population is rice-based.The high and stable yield of rice are directly related to the food safety of the whole world.As a kind of regulator,miRNA plays an important role in plant growth and development,and is widely involved in a variety of biological processes,including coping with environmental stimuli,resistance to pathogen invasion and affecting plant development.In the preliminary work of this experimental project,more than 30 miRNAs associated with rice blast resistance were screened by high throughput sequencing.In this paper,I have studied 5 miRNA about the molecular mechanism of resistance to rice blast.By building Osa-miR535,Osa-miR160,Osa-miR2869,Osa-miR2871 and Osa-miR1861 overexpressing transgene lines,Target Mimicry overexpressing transgene lines and target overexpressing transgene lines,checking their resistance to rice blast and agronomic traits.The main results are as followes:The mRNA accumulation level of Osa-miR535 predicted target gene Os02g09080,Os03g14880,Os04g47580,OsSPL14 and OsSPL12 are down regulated in miR535 overexpressing transgene lines,and OsSPL14 down regulated the most significant.Upon M.oryzae infection,the miR535 overexpressing transgene lines became more susceptible to M.oryzae than wide type,and the defense related gene OsPRl,OsNAC4 and OsKS4 were inhibited in miR535 overexpressing transgene lines.Upon M.oryzae infection,the Target Mimicry of miR535 transgene lines became more resistant to M.oryzae,and the expression of OsSPL14 was up-regulated.Upon M.oryzae infection,OsSPL14 was up regulated in IRBLkm-Ts and down regulated in LTH.Overexpression of miR535 incressed the tiller number of rice and decreased the size of rice inflorescence.Overexpression of miR535 Target Mimicry decreased the tiller number.In summary,miR535 negatively regulated rice defense to rice blast and influence tiller nuber of rice by inhibited the expression of SPL14.Overexpression of miR160a regulate the expression of its five target genes,three of them were significantly inhibited,and two of them were not.That leading to increased tiller angle of rice,and grain became larger.5 miR160a target genes were up regulated in the two Target Mimicry transgene lines eTM 160a and MIM 160a,leading to rice grain smaller and even no seed.Building overexpressing transgene lines of miR160a target genes,Os04g59430,Os02g41800 and Os10g33940,I found overexpressing Os04g59430 made rice pollen abortion and without grain.Infected miR1861,miR2871 and miR2869 with M.oryzae for primary disease resistance identification,I found miR1861 and miR2869 negatively regulate rice resistance to rice blast;and miR2871 positively regulate rice resistance to rice blast.