Transcriptional Analysis of C-Repeat Binding Factors in Fruit of Citrus Species with Differential Sensitivity to Chilling Injury during Postharvest Storage

Abstract

Citrus fruit are sensitive to chilling injury (CI) during cold storage, a peel disorder that causes economic losses. C-repeat binding factors (CBFs) are related to cold acclimation and tolerance in different plants. To explore the role of <i>Citrus</i> CBFs in fruit response to cold, an in silico study was performed, revealing three genes (<i>CBF1</i>, <i>CBF2</i>, and <i>CBF3</i>) whose expression in CI sensitive and tolerant cultivars was followed. Major changes occurred at the early stages of cold exposure (1–5 d). Interestingly, <i>CBF1</i> was the most stimulated gene in the peel of CI-tolerant cultivars (Lisbon lemon, Star Ruby grapefruit, and Navelina orange), remaining unaltered in sensitive cultivars (Meyer lemon, Marsh grapefruit, and Salustiana orange). Results suggest a positive association of <i>CBF1</i> expression with cold tolerance in <i>Citrus</i> cultivars (except for mandarins), whereas the expression of <i>CBF2</i> or <i>CBF3</i> genes did not reveal a clear relationship with the susceptibility to CI. Light avoidance during fruit growth reduced postharvest CI in most sensitive cultivars, associated with a rapid and transient enhance in the expression of the three CBFs. Results suggest that CBFs-dependent pathways mediate at least part of the cold tolerance responses in sensitive <i>Citrus</i>, indicating that <i>CBF1</i> participates in the natural tolerance to CI.