Ectopic co-expression of endosome located V-ATPase subunit gene and NHX transporter gene from Helianthus tuberosus enhances rice growth and nutrient uptake

Abstract

V-type H+-ATPase (VHA) at vacuolar and endosome systems can provide the driving force for activating intracellular Na+(K+)/H+ (NHX) antiporters. We have previously shown that expression of an endosomal located HtNHX2 from Helianthus tuberosus increased rice tolerance to K+-limited salt stress or general deficiency of nutrients. In this study, we cloned HtVHA-c” also from Helianthus tuberosus and found that HtVHA-c” is mainly located on endosome and trans-Golgi network/Golgi network. Expression of HtVHA-c” enhanced salt-tolerance of BY2 cells at the cellular level and growth of rice at salt-stress by increasing K+ acquisition. Co-expression of HtVHA-c” and HtNHX2 could further promote K+ uptake and increase growth and grain yield of rice at non-salt-stress and sufficient nutrient supply condition in both hydroponic culture and paddy field. Notably, HtVHA-c” acidified while HtNHX2 alkalized luminal of prevacuolar compartments/multivesicular bodies and vacuoles, while these effects were neutralized when both genes were expressed in rice. These results demonstrate the novel synergistic function of VHA-c” and NHX2 in regulating the luminal pH of endosomes for improving plant mineral nutrition and salt tolerance.