Data_Sheet_1_Salinity Tolerance of Two Potato Cultivars (Solanum tuberosum) Correlates With Differences in Vacuolar Transport Activity.xlsx

2018-06-05T09:18:17Z (GMT) by Rinse Jaarsma Albertus H. de Boer
<p>Potato is an important cultivated crop species and since it is moderately salt sensitive there is a need to develop more salt tolerant cultivars. A high activity of Na<sup>+</sup> transport across the tonoplast in exchange for H<sup>+</sup> is essential to reduce Na<sup>+</sup> toxicity. The proton motive force (PMF) generated by the V-H<sup>+</sup>-ATPase and the V-H<sup>+</sup>-PPase energizes the Na<sup>+</sup>(K<sup>+</sup>)/H<sup>+</sup> antiport. We compared the activity, gene expression, and protein levels of the vacuolar proton pumps and the Na<sup>+</sup>/H<sup>+</sup> antiporters in two potato cultivars (Solanum tuberosum) contrasting in their salt tolerance (cv. Desiree; tolerant and Mozart; sensitive) grown at 0 and 60 mM NaCl. Tonoplast-enriched vesicles were used to study the pump activity and protein levels of the V-H<sup>+</sup>-ATPase and the V-H<sup>+</sup>-PPase and the activity of the Na<sup>+</sup>/H<sup>+</sup> antiporter. Although salt stress reduced the V-H<sup>+</sup>-ATPase and the V-H<sup>+</sup>-PPase activity in both cultivars, the decline in H<sup>+</sup> pump activity was more severe in the salt-sensitive cultivar Mozart. After salt treatment, protein amounts of the vacuolar H<sup>+</sup> pumps decreased in Mozart but remained unchanged in the cultivar Desiree. Decreased protein amounts of the V-H<sup>+</sup>-PPase found in Mozart may explain the reduced V-H<sup>+</sup>-PPase activity found for Mozart after salt stress. Under non-stress conditions, protein amounts of V-H<sup>+</sup>-PPase were equal in both cultivars while the V-H<sup>+</sup>-PPase activity was already twice as high and remained higher after salt treatment in the cultivar Desiree as compared to Mozart. This cultivar-dependent V-H<sup>+</sup>-PPase activity may explain the higher salt tolerance of Desiree. Moreover, combined with reduced vacuolar H<sup>+</sup> pump activity, Mozart showed a lower Na<sup>+</sup>/H<sup>+</sup> exchange activity and the K<sub>m</sub> for Na<sup>+</sup> is at least twofold lower in tonoplast vesicles from Desiree, what suggests that NHXs from Desiree have a higher affinity for Na<sup>+</sup> as compared to Mozart. From these results, we conclude that the higher capacity in combination with the higher affinity for Na<sup>+</sup> uptake can be an important factor to explain the differences in salt tolerance of these two potato cultivars.</p>