Exogenous salicylic acid regulates organic acids metabolism in postharvest blueberry fruit

Abstract

Fruit acidity is an essential factor affecting blueberry organoleptic quality. The organic acid content in blueberry fruit mainly contributes to fruit acidity. This study aims to evaluate the effect of exogenous salicylic acid (SA), the principal metabolite of aspirin, on the organoleptic quality and organic acid metabolism in rabbiteye blueberry (Vaccinium virgatum Ait, ‘Powderblue’) during cold storage (4 °C). Results showed that SA-treated fruit reduced fruit decay and weight loss delayed fruit softening, and decline of total soluble solids (TSS). TA and total organic acid amounts stayed the same during the late storage period in SA-treated fruit. Four kinds of organic acid components, malic acid, quinic acid, citric acid, and succinic acid, were at higher levels in fruit treated by SA as compared to control. SA enhanced the activities of PEPC, NAD-MDH, and CS to promote the synthesis of malic acid and citric acid. Meanwhile, the activities of NADP-ME, ACL, and ACO, which participated in the degradation of malic acid and citric acid, were inhibited by SA. qPCR results also showed that the expression of VcPEPC, VcNAD-MDH, and VcCS genes were upregulated. In contrast, SA downregulated the expression of VcNADP-ME, VcACL, and VcACO genes. In conclusion, SA could regulate the key genes and enzymes that participated in organic acids metabolism to maintain the freshness of blueberry during cold storage, therefore minimizing the economic loss.

Maintenance of postharvest storability and overall quality of ‘Jinshayou’ pummelo fruit by salicylic acid treatment

“…As the main secondary metabolites in plants, both phenolics and flavonoids are not only closely associated with the color conversion, flavor formation, and stress resistance of harvested fruits, but also protect them from over-produced ROS-caused oxidative damage ( Ackah et al., 2022 ; Jiang et al., 2022 ). TPC is one of the important indexes to evaluate the antioxidant capacity of harvested fruits.…”

“…Pummelo fruit, being a typical non-climacteric variety, is prone to a rapid decline in nutritional quality when stored at room temperature, thus limiting its storability. Numerous studies have revealed that pre-storage SA treatment prior to storage can delay postharvest senescence and quality deterioration of a variety of horticultural fruits, including apricot, blueberry, cornelian cherry, goji berry, papaya, pear, winter jujube, and tomato, as well as improve their resistance to abiotic stress ( Dokhanieh et al., 2013 ; Hanif et al., 2020 ; Kumar et al., 2021 ; Zhang et al., 2021a ; Jiang et al., 2022 ; Li et al., 2022 ; Sinha et al., 2022 ; Zhang et al., 2022 ). In this study, pre-storage application of SA was found to effectively in delaying fruit color change and decreasing h° and ΔE values, as well as reducing fruit decay and weight loss of harvested ‘Jinshayou’ pummelo fruit during storage at room temperature ( Figures 1A–E ).…”

“…In higher plants, AsA and GSH are both representative substrates in AsA-GSH system (Halliwell-Asada cycle) for scavenging over-accumulated ROS in fruit, which maintains ROS homeostasis and delays cell senescence caused by oxidative stress ( Serna-Escolano et al., 2021 ; Hanaei et al., 2022 ; Peng et al., 2022 ). Additionally, phenolics compounds are a class of plant secondary metabolites that perform a pivotal role in the color conversion, flavor formation, and stress resistance of harvested fruits, in conjunction with flavonoids, which protect them from the oxidative damage caused by the over-production of ROS ( Ackah et al., 2022 ; Jiang et al., 2022 ). Therefore, high levels of antioxidants (AsA, GSH, phenolics, and flavonoids) contents are closely related to the fruit’s resistance to postharvest senescence stress.…”

“…In addition, 2 mM SA treatment reduced postharvest decay and pulp browning of ‘Patharnakh’ pear by maintaining fruit firmness and nutritional quality, inhibiting fruit respiration, and enhancing the antioxidant system, whereas the high browning index correlated to the high PPO activity and the low total phenolics content (TPC) was observed in the control fruit ( Adhikary et al., 2021 ). Furthermore, postharvest SA application is proved to be beneficial for enhancing nutritional quality and antioxidant potential of berry fruits (cornelian cherry, blueberry, and tomato) in the period of storage ( Dokhanieh et al., 2013 ; Kumar et al., 2021 ; Jiang et al., 2022 ).…”

Apple polyphenols delay postharvest senescence and quality deterioration of ‘Jinshayou’ pummelo fruit during storage

“…Additionally, GSH is another representative substrate in AsA-GSH system involved in the clearance of ROS over-accumulation, which maintains ROS homeostasis and delays cell senescence caused by oxidative stress ( Hanaei et al., 2022 ; Peng et al., 2022 ). Phenolics compounds are a class of plant secondary metabolites that perform a pivotal role in the color conversion, flavor formation, and stress resistance of harvested fruits, in conjunction with flavonoids, which protect them from the oxidative damage caused by the over-production of ROS ( Ackah et al., 2022 ; Jiang et al., 2022 ). Therefore, high levels of antioxidants (AsA, GSH, phenolics, and flavonoids) contents are closely related to the fruit’s resistance to postharvest senescence stress.…”