Pruning length of lateral branches influences auxin and cytokinins homeostasis in relation to growth and yields in Solanum lycopersicum L.

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 it-mediated physiological and molecular mechanisms 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 on 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 had inhibited effect on auxin outflow of the lower fruit stalks by testing transcripts of AUX1 and PIN , which increased the IAA and CKs concentrations of ovary and then promoted fruit setting and swelling. Additionally, pruning length of LBs also influenced the leaf senescence to control assimilation. Taken together, we highlighted that pruning length of LBs influenced auxin and cytokinins homeostasis in relation to growth and yields in tomato plants.