Physiological characteristics and alternative respiratory pathway under salt stress in two wheat cultivars differing in salt tolerance

Changes in respiratory pathway, dry weight, contents of proline, ATP Na+ and K+ were investigated under five salinity treatments in the leaves of plants of spring wheat (Triticum aestivum L.). Two cultivars differing in salt resistance, namely, 89122 (salt-tolerant) and Longchun 13 (salt-sensitive), were used. The decrease in dry weight and K+ content was observed with the increasing NaCl concentrations, but more in cv. 89122 plants than in Longchun 13 plants. Contents of proline and Na+ in both cvs increased greatly, but the former increased more in 89122 while the latter more in Longchun 13 plants. In all salinity treatments tested, a salt-induced increase in the activity of the alternative pathway was found, although cytochrome pathway (CP) still remained the main electron transport pathway. ATP production changed in parallel with CP operation. Cv. 89122 plants could produce more ATP than cv. Longchun 13 plants exposed to each salinity treatment and their ATP generation could even be stimulated in contrast to its rapidly decline in Longchun 13 plants with increased salinity stress. The possible relationship between respiration metabolism and above mentioned physiological changes is discussed.