Solute Accumulation in the Apex and Leaves of Wheat During Water Stress

Abstract

Accumulation of several low-molecular-weight solutes was measured in the developing floral apex, in an enclosed, elongating leaf, and in an expanded leaf of wheat plants during a 13-day period of water stress. In the apices and enclosed leaves, osmotic potential fell from - 1.2 to -4.0 MPa. The main contribution to the decline in osmotic potential during the first 3 days of stress was from an increase in the content of ethanol-soluble carbohydrate. Later, increases in the concentrations of both carbohydrates and amino acids made major contributions. Of the amino acids, the largest increases were in asparagine and proline. The enclosed tissues lost little water, although the water- to-dry matter ratio declined as a result of imported solutes. The ethanol-insoluble nitrogen content of apices remained high, and growth of apices and enclosed leaves recommenced when plants were watered after 13 days. In exposed leaves, increases in carbohydrate and amino acid contents were comparatively small, and the content of ethanol-insoluble nitrogen decreased by 50%. These leaves dehydrated within 6 days, and failed to recover when the plants were rewatered.

Survival and recovery of perennial forage grasses under prolonged Mediterranean drought: II. Water status, solute accumulation, abscisic acid concentration and accumulation of dehydrin transcripts in bases of immature leaves

“…potential could be explained by contribution of minerals, of which potassium was dominant. The major role of potassium and free amino acids was also shown in leaf bases of cereals subjected to rapid (3 d) desiccation (Munns et al, 1979 ;Barlow et al, 1980). However, in our study, amino acids and proline contributed by less than 2-3 % to bulk osmotic potential, which was about twice as great in ryegrass as in cocksfoot.…”

Plant Water-Stress Response Mechanisms

“…Among the major effects are those involving carbohydrate metabolism, with the accumulation of sugars and a number of other organic solutes [75]. Munns et al, (1979) [76] and Quick et al, (1992) [60] showed that sugars are major contributors to osmotic adjustment in expanding wheat leaves. Moreover, short-term water stress inhibited starch synthesis more strongly than sucrose synthesis, in both ambient CO 2 and in saturating CO 2 .…”

Physiological changes of pepper accessions in response to salinity and water stress

“…In general, one of the important pathways to enhance water stress and salt tolerance is through osmotic adjustment (OA), in which leaf turgor remains necessary for stomatal opening and, thus, sustains photosynthesis and growth (Huang et al, 2010;Nio et al, 2011). Besides, various types of compatible solutes accumulate, such as sugars, proline, gycinebetaine or potassium, among others (Munns et al, 1979;Morgan, 1992;Nio et al, 2011), and can increase. These compounds can be added to the list of the non-enzymatic antioxidants that plants need to counteract the inhibitory metabolic effects of reactive oxygen species (ROS) provoked by stress (Gill & Tuteja, 2010;Penella et al, 2014aPenella et al, , 2016.…”