Regulation of a-galactosidase gene expression in primary foliage leaves of barley ( Hordeum vulgare L.) during dark-induced senescence

Abstract

alpha-Galactosidase activity (alpha- d-galactoside galactohydrolase, EC 3.2.1.22) increased during dark-induced senescence in primary foliage leaves of barley ( Hordeum vulgare L. cv. Steffi). The changes in activity were accompanied by parallel changes in expression of the HvSF11 gene encoding a putative alpha-galactosidase. The transcript level of HvSF23 encoding a second putative alpha-galactosidase stayed constant during leaf senescence. Both alpha-galactosidase activity and the level of the HvSF11 transcript decreased after exogenous application of sucrose and glucose to detached dark-incubated leaves. In contrast, the HvSF23 transcript level was not influenced by sugars. Application of glucose analogs to detached and dark-incubated leaves revealed that phosphorylation of hexose by hexokinase modulates both the alpha-galactosidase activity and the expression of HvSF11. These results indicate that the expression of the genes coding for two alpha-galactosidase isoenzymes is regulated by different signalling pathways, suggesting different functions for the two gene products.

Cytokinin delays dark-induced senescence in rice by maintaining the chlorophyll cycle and photosynthetic complexes

“…The plant hormone CK is known to delay senescence in plants. BA-treated detached N22 leaves and untreated detached leaves of the N22-H-dgl162 mutant showed a delay in senescence when subjected to DIS, a commonly used procedure for artificially inducing senescence by dark treatment of detached leaves to obtain uniformity and save time while performing experiments ( Oh et al , 2003 ; Chrost et al , 2004 ). The physiological parameters indicated that delays in initiation of Chl degradation and loss of photosynthetic efficiency contribute to delayed senescence.…”

Leaf senescence induced by EGY1 defection was partially restored by glucose in Arabidopsis thaliana

“…Darkness treatment induced uniform and rapid senescence (Chrost et al 2004; del Rio et al 2003; Mishev et al 2009). After 3 days of dark treatment, egy1 mutant leaves were more yellow while the phenotype of WT plants had no obvious changes (Fig.…”