Chloroplast phosphate transporter DoPHT2;1 maintains phosphate and sucrose homeostasis in Dendrobium officinale Kimura et Migo

Dendrobium officinale Kimuraet et Migo (D. officinale) was included in the list of homology of medicine and food. The main active substances of D. officinale is polysaccharides (DOP), and the sucrose is the raw materials for DOP synthesis. Therefore, exploring the environmental factors affecting sucrose synthesis will provide important support for revealing the formation rules of D. officinale quality. We found phosphorus content was significantly correlated with sucrose metabolism. We performed WGCNA analysis and found a chloroplasts localized phosphate transporter protein DoPHT2;1. The expression of DoPHT2;1 is highly correlated with sucrose metabolism genes by transcriptome data analysis. Overexpression of DoPHT2;1 in A.thaliana and D. officinale protocorm-like bodies promote the accumulation of sucrose. Furthermore, Y1H and EMSA showed the low-phosphorus response transcription factor WRKY70 can bind the promoter cis-acting element of DoPHT2;1. We conclude that DoPHT2;1 is responsible for phosphorus transport in chloroplasts and for maintaining sucrose balance.