Journal Article

Topping Inhibited Potassium Uptake via Regulating Potassium Flux and Channel Gene Expression in Tobacco

Wang, Guiyao, Liang, Taibo, Dai, Huaxin, Zhang, Yanling, Meng, Xiangyu, Khan, Waleed Amjad, Guo, Yadi

2022

Overview

Potassium (K+) is mainly absorbed by plants from the soil and is primarily transported within the plant through the xylem. Topping has been reported to cause efflux and loss of K+ in plants; however, its effect on the real-time flow rate and genotypes with varying K+ accumulation ability is still unknown. Therefore, we carried out a pot experiment containing sand culture using two tobacco cultivars EY1 (high K+ accumulating) and Y87 (low K+ accumulating). The results demonstrated the change of K+ flow direction from influx to efflux in the roots of both cultivars due to topping. The percentage ratio of K+ efflux to influx was estimated to be 18.8% in EY-1 and 157.0% in Y87, respectively. We noticed a decline in indole acetic acid (IAA) content due to topping, which activated the expression of K+ efflux channel gene NTORK1 and inhibited the expression of K+ influx channel genes NKT1 and NtKC1. Furthermore, K+ loss from the roots increased due to topping, which led to decreased K+ concentration in entire tobacco plant. Topping had a more serious impact on the K+ efflux rate and K+ loss in Y87. IAA application after topping, in turn, decreased the K+ loss in both the cultivars. We conclude that topping caused a decrease in IAA concentration and K+ losses in tobacco leaves, and these losses can be mitigated by the exogenous application of IAA.

• Publisher: MDPI AG
• Subject: Accumulation / Acetic acid / Cultivars / Efflux / Flow rates / Flow velocity / Gene expression / Genotypes / Indoleacetic acid / Nitrogen / Potassium / potassium flux / Roots / Starvation / Tobacco / topping / Xylem