Zinc Requirement for Stomatal Opening in Cauliflower

Abstract

Zn deficiency induced increases in epicuticular wax deposits, lamina thickness, degree of succulence, water saturation deficit, diffusive resistance, and proline accumulation and decreases in carbonic anhydrase activity, water potential, stomatal aperture, and transpiration in the leaves of cauliflower (Brassica oleracea L. var botrytis cv Pusa) plants. Restoration of Zn supply to the deficient plants increased stomatal aperture, transpiration, and carbonic anhydrase activity significantly within 2 h. However, leaf water potential in the Zn-deficient plants did not recover within 24 h after resupply of Zn. The guard cells in epidermal peels from the Zndeficient leaves had less K+ than those from the controls. Stomatal aperture in the epidermal peels from Zn-deficient leaves was 64% less than in the controls when the epidermal strips were floated on 125 mM KCI. Supplementing the ambient medium 25 mM KCI with ZnCI, enhanced stomatal aperture in both control and Zn-deficient peels, and the effect was significant in the latter. The observations indicate involvement of Zn in stomatal opening, possibly as a constituent of carbonic anhydrase needed for maintaining adequate [HCO;] in the guard cells, and also as a factor affecting K+ uptake by the guard cells.Previous studies have shown that Zn deficiency stress decreased ij, stomatal aperture, and E and increased WSD in cabbage (Brassica oleracea capitata) (Sharma et al., 1982(Sharma et al., , 1984 and cauliflower (Brassica oleracea botrytis) (Sharma and Sharma, 1987). Hu and Sparks (1991) reported a significant decrease in stomatal conductance in Zn-deficient Stuart pecan leaves. According to Sharma et al. (1982) and Sharma and Sharma (1987), decrease in stomatal opening and transpirational water loss from Zn-deficient cabbage leaves can be attributed to decreased water potential.

Drought tolerance in Zn-deficient red cabbage (Brassica oleracea L. var. capitata f. rubra) plants

“…Lower leaf surface area could resulted from both impaired cell division and cell expansion due to the effect of Zn in DNA metabolism (Marschner 1995) and loss of membrane integrity resulting in disturbance of ion balance and cell expansion, respectively. Similar explanation was used for the effect of Zn deficiency on the guard cells (Sharma et al 1995). Lower water availability for cell turgidity and cell wall extension are involved likely in the impaired leaf surface area in Zn-deficient plants subjected to drought stress.…”

“…Effect of Zn deficiency on photochemical processes as well as CO 2 assimilation rate was reported for some plant species (Hajiboland, Beiramzadeh 2008;Wang et al 2009). These effects are likely mediated by changes in the ultrastructure of thylakoid membranes (Chen et al 2007), in stomatal conductance (Sharma et al 1995) and carbohydrate metabolism (Marschner 1995).…”

Zinc stress induces physiological, ultra-structural and biochemical changes in mandarin orange (Citrus reticulata Blanco) seedlings

“…Zn plays a greater role in stomatal opening by its structural involvement in CA, that is needed for maintaining adequate HCO 3 − in the guard cells and by controlling the K + uptake by the guard cells (Sharma et al 1995). Due to absence of Zn, the activity of CA decreased, K + influx was low and thus the guard cells remained partially opened and the shape of the guard cells became almost round in the Zn deficient mandarin plants (Fig.…”

“…Zn control K + uptake by the guard cells and Zn deficiency probably decreased accumulation of K + and other solutes in guard cells. Stomatal opening is controlled by carbonic anhydrase (CA), which maintain adequate HCO 3 − in the guard cells and here Zn plays a vital role (Sharma et al 1995). The highest Pn, gs and E were found in plants treated with 5 mM Zn implying that, optimal Zn application did not interfere with the gas exchange parameters in these plants (Table 1).…”

Growth, photosynthesis and antioxidant defense systém in Zn-deficient red cabbage plants

“…in addition of the expected effect on photochemical processes, involvement of Zn in carbohydrate metabolism was demonstrated through its effect on net Co 2 assimilation rate via stomatal conductance (Sharma et al 1995) and sugar transformations (Marschner 1995). inhibition of activity of rubisco, aldolase, sucrose synthase and starch synthetase in plant tissues due to Zn starvation has been suggested (Marschner 1995).…”