Low temperature modulates natural peel degreening in lemon fruit independently of endogenous ethylene

Oscar W. Mitalo, Takumi Otsuki, Rui Okada, Saeka Obitsu, Kanae Masuda, Yuko Hojo, Takakazu Matsuura, Izumi C. Mori, Daigo Abe, William O. Asiche, Takashi Akagi, Yasutaka Kubo, Koichiro Ushijima

Research output: Contribution to journalArticlepeer-review

Abstract

Peel degreening is an important aspect of fruit ripening in many citrus fruit, and previous studies have shown that it can be advanced by ethylene treatment or by low-temperature storage. However, the important regulators and pathways involved in natural peel degreening remain largely unknown. To determine how natural peel degreening is regulated in lemon fruit (Citrus limon), we studied transcriptome and physiochemical changes in the flavedo in response to ethylene treatment and low temperatures. Treatment with ethylene induced rapid peel degreening, which was strongly inhibited by the ethylene antagonist, 1-methylcyclopropene (1-MCP). Compared with 25 ºC, moderately low storage temperatures of 5-20 °C also triggered peel degreening. Surprisingly, repeated 1-MCP treatments failed to inhibit the peel degreening induced by low temperature. Transcriptome analysis revealed that low temperature and ethylene independently regulated genes associated with chlorophyll degradation, carotenoid metabolism, photosystem proteins, phytohormone biosynthesis and signalling, and transcription factors. Peel degreening of fruit on trees occurred in association with drops in ambient temperature, and it coincided with the differential expression of low temperature-regulated genes. In contrast, genes that were uniquely regulated by ethylene showed no significant expression changes during on-tree peel degreening. Based on these findings, we hypothesize that low temperature plays a prominent role in regulating natural peel degreening independently of ethylene in citrus fruit.

Original languageEnglish
Pages (from-to)4778-4796
Number of pages19
JournalJournal of experimental botany
Volume71
Issue number16
DOIs
Publication statusPublished - Aug 1 2020

Keywords

  • 1-methylcyclopropene
  • Carotenoids
  • Chlorophyll
  • Citrus limon
  • Ethylene
  • Low temperature
  • Peel degreening
  • Phytohormones
  • Transcriptome

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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