Application Of Cassava Nitrate Transporter SLAH4 In Rice Improvement

Nitrogen is an important nutrient element for plant growth and development.The ability of plants to obtain nitrogen from soil depends on soil type,environment and species.It is of great significance to improve nitrogen use efficiency for reducing fertilizer costs in plant production and avoiding environmental damage caused by nitrate leaching ecosystem saturation and water pollution.Improve plant for efficient nitrogen absorption is slow nitrogen and the most effective way of nitrogen fertilizer on the environment destruction Cassava is important food crops and cash crops in the world,and barren resistance Characteristics of strong adaptability and resistance,outside the growth process doesn’t need too much nitrogen can obtain higher nitrogen source from the soil to satisfy their own growth and development,so exploiting cassava nitrogen efficient use of related genes,for crop germplasm improvement has important significance.In the course of plant evolution,there are two kinds of transport systems for nitrate absorption,namely low-affinity transporter systems(LATS)and high-affinity transporter systems(HATS),which consist of four families: NRT1/PTR(Nitrate Transporter 1)、 NRT2(Nitrate Transporter 2)、 CLC(Chloride channel)and SLAC/SLAH(slow anion channel protein)families.This study through the analysis of the biology of cassava MeSLAH4 promoter gene phylogenetic relationship structure cis element and chromosomal location,and MeSLAH4 gene cloning from cassava,the building carrier heterologous expression in arabidopsis and rice,the right to express plant phenotypic observation of physiological indexes and the analysis of grain traits of cassava MeSLAH4 gene function,main results are as follows:1.Phylogenetic analysis of SLAC/SLAH gene in cassava Arabidopsis indicated that MESLAH4 gene in cassava was more similar to At SLAH1 and At SLAH4 gene in Arabidopsis.The SLAC/SLAH gene family has similar gene structure and protein conserved motif.The prediction results of promoter cis-acting elements indicated that MESLAH4 contains promoter and enhancer cis-acting elements CAAT-box and tissue specific expression element CAT-box,and MeSLAH4 may have plant tissue specific expression characteristics.2.The cDNA of cassava MeSLAH4 was constructed into p CAMBIA2300-35S-e GFP vector for subcellular localization,and the results showed that MESLAH4 was localized on the cell membrane3.Tissue specific expression analysis showed that MeSLAH4 gene was mainly expressed in roots of cassava seedlings treated with 0.2 mmol/L and 10 mmol/L nitrate,and the expression level of MeSLAH4 gene was also significantly affected in stems treated with 0.2 mmol/L nitrate,indicating that MeSLAH4 gene was induced by nitrate.4.The photosynthetic efficiency and chlorophyll content of MeSLAH4 transgenic rice were significantly higher than that of control rice in the presence of nitrogen fertilizer.Phenotypic analysis of rice overexpressed with MeSLAH4 gene showed that both the transgenic lines and the control lines were subjected to a certain degree of nitrogen stress under low nitrogen treatment.The transgenic lines showed strong tolerance to low nitrogen,and their root length,root number and leaf area were significantly higher than those of the control group.5.Phenotypic observation of MeSLAH4 transgenic rice grains showed that the grain length and 1000-grain weight of transgenic rice were significantly higher than that of control rice,but the grain width did not change significantly.The results showed that MeSLAH4 gene plays an important role in rice response to nitrogen stress.Overexpression of MeSLAH4 gene can enhance rice tolerance to low nitrogen and increase grain 1000-grain weight,which has the potential to be used in crop improvement of low nitrogen tolerance.