Varied Expression of Senescence-Associated and Ethylene-Related Genes during Postharvest Storage of Brassica Vegetables

Abstract

The genus Brassica comprises a highly diverse range of vegetable crops varying in morphology, harvestable crop product, and postharvest shelf-life that has arisen through domestication, artificial selection and plant breeding. Previous postharvest studies on the shelf-life of Brassica species has mainly focused on the variable rates of physiological changes including respiration and transpiration. Therefore, further understanding of the molecular basis of postharvest senescence in Brassica vegetables is needed to understand its progression in improving their postharvest shelf-life. The aim of this study was to better understand the trajectory of molecular responses in senescence-associated genes but not induced by ethylene and ethylene-induced genes towards altered postharvest storage conditions. After storage at different temperatures, the expression levels of the key senescence-associated genes (SAGs) and the ethylene biosynthesis, perception, and signaling genes were quantitatively analyzed in cabbage, broccoli and kale. The expression levels of these genes were tightly linked to storage temperature and phase of senescence. Expression of ORE15, SAG12, and NAC29 were continuously increased during the twelve days of postharvest storage at room temperature. Prolonged exposure of these three vegetables to cold temperature reduced the variation in the expression levels of ORE15 and SAG12, observed as mostly decreased which resulted in limiting senescence. The transcript levels of the ethylene receptor were also decreased at lower temperature, further suggesting that decreased ethylene biosynthesis and signaling in cabbage during postharvest storage would delay the senescence mechanism. These results enhanced our understanding of the transcriptional changes in ethylene-independent SAGs and ethylene-related genes in postharvest senescence, as well as the timing and temperature sensitive molecular events associated with senescence in cabbage, broccoli and kale and this knowledge can potentially be used for the improvement of postharvest storage in Brassica vegetables.

Potential of Essential Oils from Active Packaging to Highly Reduce Ethylene Biosynthesis in Broccoli and Apples

“…As previously explained, low storage temperatures over the optimum product storage temperature (0–2 °C for broccoli) are interpreted by plant cells as abiotic stresses . Hence, the expression of ACC oxidase genes and its activity were induced by low temperatures in broccoli from 22 to 4 °C . Lelièvre et al observed similar results in pears reporting that ACC synthase gene expression is regulated under chilling temperatures, while ACO gene expression can be activated distinctly by either chilling or ethylene.…”

“…49 Hence, the expression of ACC oxidase genes and its activity were induced by low temperatures in broccoli from 22 to 4 °C. 52 Lelievre et al 53 observed similar results in pears reporting that ACC synthase gene expression is regulated under chilling temperatures, while ACO gene expression can be activated distinctly by either chilling or ethylene.…”

“…This obtained fast inhibitory effect with the released EOs from the active packaging is crucial since the ACC oxidase genes are highly expressed in the first hours/days after the product harvest as a response to the wounding stress, even at 4 °C, as it has been previously reported for broccoli. 47,52 Although broccoli is a vegetable with a low ethylene production rate, the inhibition of its biosynthesis is crucial for this vegetable since the induction of the ACC oxidase is regulated by ethylene. 47 Thus, it was demonstrated that application of exogenous ethylene promoted the activity of the ACC oxidase, while 2,5-norbornadiene, an inhibitor of ethylene action, suppressed it.…”

Impact of Bacterial Cellulose Nanocrystals-Gelatin/Cinnamon Essential Oil Emulsion Coatings on the Quality Attributes of ‘Red Delicious’ Apples

“…When these substrates are utilized and completely oxidized, different amounts of oxygen are consumed concerning the amount of CO 2 evolved [56]. By knowing that starch hydrolysis starts during fruit ripening and storage [57][58][59], we can indisputably assert that the lower detected TSS values of coated apples rather than uncoated samples can be ascribed to the slower respiration process, being also corroborated by the previously shown results of Figure 1b, which demonstrate the lower total sugar content in apples' tissue.…”

Identifying gene regulatory networks of senescence in postharvest broccoli (Brassica oleracea)

“…It has been reported that during the progression of senescence, certain SAGs are upregulated or downregulated. With regard to the ethylene-related genes, it has been reported that some are barely detectable in freshly harvested immature florets ( BoACO2 and BoACO3 ), while others like BoACO3 are only expressed in whole yellow florets (Ahlawat and Liu, 2021). There are also other examples of broccoli genes that exhibit different expression patterns after harvest and through senescence; for example, BoACS1 (DNA clone of ACC synthase) had high transcript levels after harvest but was not detected during storage.…”