Effects of SNP and cPTIO on oxidative membrane damage and pericarp browning of harvested longan fruit
Sitthisak Intarasit is a Ph.D. candidate in the Department of Biology at Chiang Mai University, Thailand. He completed his BSc in Biology in 2017, and his MSc in Plant Biology in 2019. These degrees were obtained from Chiang Mai University. His Ph.D. focused on browning disorder in longan (Dimocarpus longan Lour.), with emphasis on reactive nitrogen species (RNS) and nitrosative stress. Postharvest longan fruits are prone to senescence. Pericarp browning or disease development due to water loss, injury, pathogen infection, or damage caused by reactive oxygen species (ROS) severely degrades the commercial value of the fruit. Sitthisak’s research evaluated the involvement of nitric oxide (NO), an important RNS, in ROS accumulation and oxidative damage to pericarp browning of ‘Daw’ longan fruit. This damage occurred during storage under ambient condition by using sodium nitroprusside (SNP, NO donor) and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, NO scavenger) application. Longan fruits were dipped in distilled water (control), SNP (50 and 100 mM) or cPTIO (100 and 500 µM) for 10 min, then stored at 25±1°C for 7 days. SNP-treated fruit exhibited higher ROS content (superoxide radical, hydrogen peroxide and hydroxyl radical), oxidative membrane damage (malondialdehyde, protein carbonyl and electrolyte leakage) as well as pericarp browning (browning index and polyphenol oxidase activity), compared with control fruits. In contrast, exposure to cPTIO attenuated ROS content, oxidative membrane damage and pericarp browning of longan pericarp during storage. The severity of pericarp browning, ROS production and oxidative damage depended on SNP or cPTIO concentrations. These findings suggest that NO might be involved in oxidative stress, which contributes to pericarp browning in harvested longan by alteration of the balance between ROS generation and scavenging. The results of Sitthisak’s research will improve the knowledge on RNS metabolism and cellular damage in response to pericarp browning of postharvest longan fruit. Moreover, his research will provide a scientific basis and reference to further investigation of postharvest quality maintenance of longan and other fruits by regulating RNS metabolism and RNS-induced oxido-nitrosative stress.
Sitthisak Intarasit won the ISHS Young Minds Award for the best oral presentation at the V Asia Symposium on Quality Management in Postharvest Systems in Thailand in December 2021.
Sitthisak Intarasit, Department of Biology, Chiang Mai University, 50200 Chiang Mai, Thailand, e-mail: firstname.lastname@example.org
The article is available in Chronica Horticulturae