Genome-wide identification and transcript analysis of vacuolar-ATPase genes in citrus reveal their possible involvement in citrate accumulation

* Figure (i) shows the Anliu (AL) and Hong Anliu (HAL) fruit samples at four development stages and their corresponding citric acid contents are in figure (ii). Figure (iii) shows the structure of V-ATPase subunits and the lower transcript levels of V1-A, V1-C, V1-E1, V1-H2, V0-a2, V0-c4, and V0-d (their corresponding subunits were in gray background) may be another reason resulting in the low accumulation of citric acid content in 'HAL' fruits as compared to 'AL' fruits.233