木薯糖转运蛋白基因MeSWEET2b的克隆及其低温胁迫下的功能研究OA

[Objective]To study the function of the MeSWEET2b gene in cassava(Manihot esculenta Crantz)under low-temperature stress,and to provide theoretical basis for exploring the molecular mechanism of cassava tolerance to cold and breeding new varieties with low-temperature tolerance.[Method]Bioinformatics method was used to analyze the sequence characteristics,phylogenetic relationships of the MeSWEET2b gene.Transient expression of the MeSWEET2b protein in tobacco was to determine its subcellular localization.RT-qPCR was adapted to analyze the expressions of the MeSWEET2b gene at different growth stages,under darkness treatments of different sugar and low-temperature stress.Virus induced gene silencing(VIGS)technology was applied to study the function of this gene under low-temperature stress.[Result]The MeSWEET2b protein had 7 transmembrane domains,and phylogenetic tree analysis indicated that it belonged to the SWEETs Clade I subfamily and had the closest homology with Arabidopsis AtSWEET2.The subcellular localization results showed that MeSWEET2b was located on the cell plasma membrane.The RT-qPCR analysis showed that MeSWEET2b had the highest expression in the leaves during the expansion period(7 months).For the water culture seedlings of cassava treated with different sugars,the expression trends of MeSWEET2b in glucose and fructose were consistent.As the temperature of cold stress decreased and the time extended,the expression of MeSWEET2b in cassava showed a significantly increased.Using VIGS technology to silence MeSWEET2b,under 4℃low-temperature stress,the wilting of the leaves in the MeSWEET2b silenced plants were significantly more severe than that of the control,and the contents of glucose and fructose significantly reduced.[Conclusion]The silencing of MeSWEET2b gene led to the intolerance of cassava to low temperatures.It is speculated that this gene plays an important role in the cold tolerance of cassava.