Metabolomic analyses provide insights into the preharvest rind disorder in Satsuma Owari Mandarin

Tariq Pervaiz; Suejin Park; Alaaeldin Rezk; Manhoi Hur; David Obenland; Mary Lu Arpaia; Ashraf El-Kereamy

doi:10.3389/fpls.2023.1263354

Metabolomic analyses provide insights into the preharvest rind disorder in Satsuma Owari Mandarin

Front Plant Sci. 2023 Sep 26:14:1263354. doi: 10.3389/fpls.2023.1263354. eCollection 2023.

Authors

Tariq Pervaiz¹, Suejin Park², Alaaeldin Rezk¹, Manhoi Hur³, David Obenland⁴, Mary Lu Arpaia¹, Ashraf El-Kereamy¹

Affiliations

¹ Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States.
² Department of Horticulture, Jeonbuk National University, Jeonju, Republic of Korea.
³ Metabolomics Core Facility, Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA, United States.
⁴ United States Department of Agriculture (USDA), Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Parlier, CA, United States.

Abstract

Citrus fruit's appearance is the primary criterion used to assess its quality for the fresh market, hence the rind's condition is a crucial quality trait. Pre-harvest rind disorder is one of the major physiological problems in mandarins. The disorder occurs right before harvest following rain events in some Mandarin varieties. Despite the economic damage caused by this kind of disorder, very limited information is available about the molecular mechanisms underlying the occurrence of this disorder. In the present study, we evaluated the primary metabolites, antioxidants, and hormones associated with the pre-harvest rind disorder in Mandarins. The study was carried out using ten-year-old 'Owari' Satsuma mandarin trees grafted on 'Carrizo' rootstock and grown in a commercial orchard in San Joaquin Valley, California, USA. Samples were collected from healthy tissue of healthy fruit (HF_HT), healthy tissue of damaged fruit (DF_HT), and damaged tissue of damaged fruit (DF_DT). Damaged fruit (DF_HT and DF_DT) showed lower cellulose concentrations than healthy fruit tissues (HF_HT), however, had similar contents of pectin and hemicellulose. The antioxidant activities showed no significant difference in all paired comparisons between samples as expressed in the malondialdehyde (MDA) content. However, DF_DT had a higher H₂O₂ content compared to HF_HT, but DF_HT had a similar content to that of HF_HT. Furthermore, peroxidase (POD) and polyphenol oxidase (PPO) activities were increased in DF_DT compared to HF_HT (P = 0.0294) and DF_HT (P = 0.0044), respectively. Targeted metabolomics analysis revealed that a total of 76 metabolites were identified in Satsuma rind tissues, and the relative concentrations of 43 metabolites were significantly different across studied samples. The hormonal analysis showed the involvement of jasmonate O-methyltransferase, jasmonic acid-amido synthetase JAR1-like, and JA-isoleucine may key role in causing the rind disorder in mandarins. In addition, the damaged fruit tissues have a higher level of jasmonic acid (JA), 12-oxo-phytodienoic acid, and JA-isoleucine than undamaged tissue.

Keywords: antioxidants; hormones; mandarin; metabolites; non-chilling rind disorder; rind physiological disorder.

Grants and funding

The authors declare that no financial support was received for the research, authorship, and/or publication of this article.