Cloning, characterization and expression analysis of key genes involved in ABA metabolism in Gladiolus cormels during storage

Abscisic acid (ABA) is one of the essential hormones involved in many developmental and physiological processes during plant life cycle, such as seed development, bud dormancy, fruit maturation and responses to abiotic stresses. To better understand the physiological role of ABA during Gladiolus hybridus cultivar ‘Rose supreme’ cormels dormancy release, the key genes involved in ABA biosynthesis (GhNCED) and catabolism (GhCYP707A1 and GhCYP707A2) were isolated and characterized. The deduced amino acid sequence of GhNCED shared high similarity to Crocus sativus NCED, which belongs to the same Iridaceae family as G. hybridus. Furthermore, changes in cormels sprouting, ABA content and GhNCED, GhCYP707A1 and GhCYP707A2 expression patterns during postharvest storage at 4 °C and 22 °C were investigated. The results showed that 4 °C storage condition was more effective to break cormels dormancy than 22 °C storage. ABA content gradually decreased to a level significantly in cormels stored at 4 °C. The expression of GhNCED in Gladiolus cormels stored at 4 °C gradually decreased and the transcription level was lower than cormels stored at 22 °C. Similarly, GhCYP707A2 expression level was found significantly higher in cormels kept in 4 °C storage temperature as compared to that stored at 22 °C. Moreover GhCYP707A1 was almost constantly expressed during storage at both temperature conditions. These findings indicated that ABA content may be co-regulated by GhNCED and GhCYP707A2 gene expression during postharvest storage and dormancy release of Gladiolus cormels.

► Three ABA metabolism key genes were first isolated from Gladiolus cormels.
► Changes in ABA content and genes expression during 4 °C and 22 °C storage were studied.
► ABA content significantly decreased during dormancy release.
► Changes in ABA content were positively correlated with GhNCED expression.
► Changes in ABA content were negatively correlated with and GhCYP707A2 expression.