Pruning length of lateral branches affects tomato growth and yields in relation to auxin-cytokinin crosstalt

Abstract

Lateral branches (LBs) pruning is performed frequently to keep the tomato plants in optimal growth conditions. However, the suitable pruning length of LBs, as well as the physiological and molecular mechanisms of pruning length on plant growth regulation remains elusive in tomato. The effects of pruning length of LBs from 0 to 20 cm on vegetative growth, reproductive growth, labor costs, hormone metabolism and genes transcripts were evaluated in an indeterminate type tomato cultivar. By comprehensive analysis, we provided evidence that pruning length of LBs at about 6–7 cm was suitable for plant growth, high yield, and low labor costs in tomato production. For mechanisms, appropriate extension of pruning length of LBs increased indole acetic acid (IAA) concentrations in root, which promoted the biosynthesis and upward transport of inactive cytokinins (CKs), as well as root development. Meanwhile, existence of LBs inhibited the auxin outflow of the lower flower stalks by regulating transcripts of AUX1 and PIN. Then, the enhanced concentrations of IAA and CKs in ovary could promote fruit swelling. Additionally, pruning length of LBs also influenced the leaf senescence to control photosynthesis. Taken together, we highlight that pruning length of LBs influence auxin and cytokinins homeostasis in relation to growth and yield in tomato plants.