Abstract
BackgroundSurvival of plants in response to salinity stress is typically related to Na+ toxicity, but little is known about how heterologous high-affinity potassium transporter (HKT) may help alleviate salt-induced damages in potato (Solanum tuberosum L.).ResultsIn this study, we used the Arabidopsis thaliana high-affinity potassium transporter gene (AtHKT1) to enhance the capacity of potato plants to tolerate salinity stress by decreasing Na+ content and improving K+/Na+ ratio in plant leaves, while maintaining osmotic balance. Seven AtHKT1 transformed potato lines (namely T1, T2, T3, T5, T11, T13 and T15) were compared with non-transgenic control plant at molecule and whole-plant levels. The lines T3 and T13 had the highest AtHKT1 expression with the tolerance index (an quantitative assessment) being 6.8 times that of the control. At 30 days under 100 and 150 mmol L− 1 NaCl stress treatments, the T3 and T13 lines had least reductions in net photosynthetic rate, stomatal conductance and transpiration rate among the seven lines, leading to the increased water use efficiency and decreased yield loss.ConclusionsWe conclude that the constitutive overexpression of AtHKT1 reduces Na+ accumulation in potato leaves and promotes the K+/Na+ homeostasis that minimizes osmotic imbalance, maintains photosynthesis and stomatal conductance, and increases plant productivity.
Highlights
Survival of plants in response to salinity stress is typically related to Na+ toxicity, but little is known about how heterologous high-affinity potassium transporter (HKT) may help alleviate salt-induced damages in potato (Solanum tuberosum L.)
Molecular mechanisms underlying the osmotic aspects of salt tolerance remain largely unknown [35], we suggest that a high-affinity potassium transporter (HKT) that regulates plant Na+ homeostasis plays a key role in improving salt tolerance in plants through genetic enhancement
5 days after the green shoots were transferred to the selective rooting medium (MS medium containing 102.20 μmol L− 1 kanamycin and 591.91 μmol L− 1 carbenicillin), roots were formed in the transgenic lines (Additional file 4: Figure S2c-1, − 3, and − 4) and no root was formed on the control (Additional file 4: Figure S2c-2)
Summary
Survival of plants in response to salinity stress is typically related to Na+ toxicity, but little is known about how heterologous high-affinity potassium transporter (HKT) may help alleviate salt-induced damages in potato (Solanum tuberosum L.). Salinity affects plant growth through a two-phase physiological challenge, one is osmotic stress and the other is ion toxicity [3]. Osmotic stress reduces plant growth due to decreased water potential [3], whereas sodium ions (Na+) congest to a toxic concentration that reduces potassium ions (K+) absorption. These challenges cause the disorder of a variety of biological processes in the plant, including physiological characteristics and enzyme activity [4]. HKTs have been reported to be active at the plasma membrane level [7], as the HKT transporters exclude Na+ from the leaves while increasing K+ transportation to resist salt stress [8,9,10,11]
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