The Role of Endogenous Ethylene in Carbohydrate Metabolism of Medicago sativa L. Somatic Embryos in Relation to Their Regenerative Ability

Abstract

Effects of the ethylene biosynthesis inhibitors salicylic acid (SA) and aminoethoxyvinylglycine (AVG) on germination of Medicago sativa L. somatic embryos and their conversion to seedlings in relation to carbohydrate content and a-amylase activity were studied. Both SA, an inhibitor of ACC oxidase, and AVG, an inhibitor of ACC synthase, when present in the regeneration medium (0.1 and 1 lM) were found to drastically reduce the embryo germination rate. In addition, SA and AVG were found to almost completely or completely, respectively, arrest the process of embryo conversion to seedlings. The inhibitory effects of SA and AVG on germination and conversion may indicate that the processes required endogenous ethylene. AVG and SA clearly slowed down starch disappearance during the 48-h imbibition in the regeneration medium prior to radicle elongation, which was correlated with inhibition of the activity of a-amylase, an enzyme responsible for starch hydrolysis. It is probable that ethylene may activate a-amylase in the germinating alfalfa somatic embryos. In contrast, the disappearance of soluble sugars in the embryos in the presence of the inhibitors tested was accelerated. The disappearance of soluble sugars (to null or almost null) in embryos was faster in the presence of SA in the regeneration medium after 24 and 48 h compared to the disappearance rate with AVG present in the medium. Only glucose was present after a 48-h incubation in the regeneration medium in the presence of the two ethylene biosynthesis inhibitors, in contrast to the control embryos in which glucose was not detected.

Ethephon-Induced Ethylene Enhances Starch Degradation and Sucrose Transport with an Interactive Abscisic Acid-Mediated Manner in Mature Leaves of Oilseed rape (Brassica napus L.)

“…This study confirms the involvement of ethephon-induced ethylene in leaf senescence, starch degradation, and sugar remobilization, which has also been suggested by previous studies [ 28 , 60 , 61 ] Furthermore, the present study, as far as we know, is the first to report that ethylene-enhanced sucrose accumulation, starch degradation in mature leaves, and sucrose remobilization via the phloem are eventually mediated by a synergistic interaction with ABA signaling. The further transcriptomic works and metabolites profiling studies are interesting to elucidate the ethylene-mediated ABA-dependent regulatory mechanism in terms of source-sink relation.…”

Efforts to Stimulate Morpho-Physio-Biochemical Traits of Maize for Efficient Production under Drought Stress in Tropics Field

“…In contrast, due to application of ethephon under water stress conditions, the grain weight was improved. This might be due to rapid plant senescence at the end of the reproductive phase under ethephon treatments, which might have helped to reduce water loss and increase the availability of nutrients to the kernels through remobilization [57,100].…”

Ethylene Signaling under Stressful Environments: Analyzing Collaborative Knowledge

“…In another study, exogenous ethylene inhibited sprouting potato tubers by influencing their carbohydrate metabolism [187]. Endogenous ethylene regulates Medicago sativa embryo germination and influences the activity of α-amylase and the metabolism of soluble carbohydrates [188]. The study by Wang et al [189] stated that ethylene significantly increases the fructose and glucose levels, but does not affect the sucrose and total soluble sugar contents in ripe jackfruit postharvest.…”