Calcium regulates Gladiolus flower senescence by influencing senescence associated genes

The present investigation was conducted to study the effect of calcium on senescence associated genes and delay in senescence in Gladiolus cv. White prosperity. The vase life of flower spikes significantly increased and fresh weight retained for longer duration by CaCl₂ (50 mM) treatment over control (distilled water). Calcium treatment maintained higher level of soluble proteins by decreasing protease activity. The expression of senescence associated genes viz., cysteine protease (GgCyP1), ethylene response sensor 1a (GgERS1a) and ethylene response sensor 1b (GgERS1b) was down regulated by calcium treatment during the course of flower development. The expression of above genes increased at initial stage and decreased at later stages in both control and treated spikes and the reduction was more prominent in calcium treated spikes over control. The expression of defender against apoptotic death (GgDAD1) gene was up-regulated by calcium treatment during the course of flower development. On the other hand, the expression of DAD1 genes increased gradually from I to IV stages and decreased at V stage in both control and treated spikes but the level of expression was higher under Ca treatment. The study suggests that 50 mM calcium treatment may enhance vase life or delay the senescence in gladiolus through increase in soluble proteins, decrease in protease activity, and down regulation of CyP1, ERS1a, ERS1b and up-regulation of DAD1 genes.