Function of miR399a in tomato in responding to phosphorus starvation

LI Qin, HUANG Jianzi, LI Ziwei, and HUANG Tengbo College of Life Sciences and Oceanography, Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen University, Shenzhen 518071, Guangdong Province, P. R. China Abstract: Phosphorus starvation may cause retarded plant growth and subsequently affect plant yield. As a key microRNA involved in plant response to phosphorus starvation, the function and regulatory mechanism of microRNA399 (miR399) in tomatoes (Solanum lycopersicum) remains to be elucidated. By cultivating wild type (WT) and Sly-miR399a-overexpressing (amiR399a) tomato plants under different phosphorus concentrations, the morphological indicators including root length, lateral root number, and root shoot ratio were measured for each sample. At the same time, the relative expression levels of Sly-miR399a and phosphate 2 (PHO2) gene, the contents of inorganic phosphorus, the contents of anthocyanin and chlorophyll , the activity of purple acid phosphatase and peroxidase were also determined for each sample. The results show that the expression levels of Sly-miR399a are significantly up-regulated in amiR399a plants relative to WT plants, while the expression levels of PHO2 are significantly down-regulated in amiR399a plants. Under low-concentration-phosphorus cultivation, the length of main root and the number of lateral roots significantly increase in both WT and amiR399a plants. Either in normal or