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ORIGINAL RESEARCH article

Front. Plant Sci.
Sec. Plant Biotechnology
Volume 15 - 2024 | doi: 10.3389/fpls.2024.1429321
This article is part of the Research Topic From Classical Breeding to Modern Biotechnological Advancement in Horticultural Crops - Trait Improvement and Stress Resilience, Volume II View all 6 articles

Ectopic overexpression of ShCBF1 and SlCBF1 in tomato suggests an alternative view of fruit responses to chilling stress postharvest

Provisionally accepted
Karin Albornoz Karin Albornoz 1Jiaqi Zhou Jiaqi Zhou 2Florence Zakharov Florence Zakharov 2Jonas Grove Jonas Grove 2MINMIN WANG MINMIN WANG 2Diane M. Beckles Diane M. Beckles 2*
  • 1 Department of Food, Nutrition, and Packaging Sciences, Clemson University, Clemson, South Carolina, United States
  • 2 Department of Plant Sciences, University of California, Davis, Davis, United States

The final, formatted version of the article will be published soon.

    Postharvest chilling injury (PCI) is a physiological disorder that often impairs tomato fruit ripening; this reduces fruit quality and shelf-life, and even accelerates spoilage at low temperatures. The CBF gene family confers cold tolerance in Arabidopsis thaliana, and constitutive overexpression of CBF in tomato increases vegetative chilling tolerance, in part by retarding growth, but, whether CBF increases PCI tolerance in fruit is unknown. We aimed to induce high levels of CBF1 cloned from S. lycopersicum and S. habrochaites in fruit undergoing postharvest chilling, using the stress-inducible RD29A promoter. We hypothesized that CBF1 overexpression (OE) would be induced in the cold and increase resistance to PCI. Harvested fruit were cold-stored (2.5°C) for up to three weeks, then rewarmed at 20°C for three days. Transgene upregulation was triggered during cold storage from 8.6to 28.6-fold in SlCBF1-OE, and between 3.1-to 8.3-fold in ShCBF1-OE fruit, but developmental abnormalities in the absence of cold induction were visible. Remarkably, transgenic fruit displayed worsening of PCI symptoms, i.e., failure to ripen after rewarming, comparatively higher susceptibility to decay relative to wild-type (WT) fruit, lower total soluble solids, and the accumulation of volatile compounds responsible for off-odors. These symptoms correlated with CBF1 overexpression levels. Transcriptomic analysis revealed that the ripening and biotic and abiotic stress responses were altered in the cold-stored transgenic fruit. Seedlings grown from 'chilled' and 'non-chilled' WT fruit, in addition to 'non-chilled' transgenic fruit were also exposed to 0°C to test their photosynthetic response to chilling injury. Chilled WT seedlings adjusted their photosynthetic rates to reduce oxidative damage; 'non-chilled' WT seedlings did not. Photosynthetic parameters between transgenic seedlings were similar at 0°C, but SlCBF1-OE showed more severe photoinhibition than ShCBF1-OE, mirroring phenotypic observations. These results suggest that 1) CBF1 overexpression accelerated fruit deterioration in response to cold storage, and 2) Chilling acclimation in fructus can increase chilling tolerance in seedling progeny of WT tomato.

    Keywords: Postharvest chilling injury, Solanum lycopersicum, C-binding factor (CBF1), chilling acclimation, Cold response, Fruit senescence

    Received: 07 May 2024; Accepted: 09 Jul 2024.

    Copyright: © 2024 Albornoz, Zhou, Zakharov, Grove, WANG and Beckles. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Diane M. Beckles, Department of Plant Sciences, University of California, Davis, Davis, United States

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