Overexpression of MdARD4 Accelerates Fruit Ripening and Increases Cold Hardiness in Tomato.

Tianli Guo,Changhai Liu,Chenlu Liu,Junyao Wu,Qi Jiang,Fengwang Ma,Na Wang,Yuxing Li,Xiuzhi Zhang

doi:10.3390/ijms21176182

Tianli Guo, Changhai Liu + Show 7 more

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https://doi.org/10.3390/ijms21176182

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Abstract

Ethylene plays an important role in stress adaptation and fruit ripening. Acireductone dioxygenase (ARD) is pivotal for ethylene biosynthesis. However, the response of ARD to fruit ripening or cold stress is still unclear. In this study, we identified three members of Malus ARD family, and expression profile analysis revealed that the transcript level of MdARD4 was induced during apple fruit ripening and after apple plants were being treated with cold stress. To investigate its function in cold tolerance and fruit ripening, MdARD4 was ectopically expressed in Solanum lycopersicum cultivar ‘Micro-Tom’, which has been considered as an excellent model plant for the study of fruit ripening. At the cellular level, the MdARD protein expressed throughout Nicotiana benthamiana epidermal cells. Overexpression of MdARD4 in tomato demonstrated that MdARD4 regulates the ethylene and carotenoid signaling pathway, increases ethylene and carotenoid concentrations, and accelerates fruit ripening. Furthermore, MdARD4 increased the antioxidative ability and cold hardiness in tomato. To conclude, MdARD4 may potentially be used in apple breeding to accelerate fruit ripening and increase cold hardiness.

Highlights

Ripening of fleshy fruits is a complex process that involves biochemical and metabolic changes
The function of MdARD4 in fruit ripening is unknown and whether it is involved in ethylene biosynthesis and signaling pathway is unclear
Overexpression of MdARD4 induced the expression of genes involved in ethylene biosynthesis and response, improved ethylene concentration and shortened fruit maturation time

Summary

Introduction

Ripening of fleshy fruits is a complex process that involves biochemical and metabolic changes. The natural plant hormone, regulates various physiological and developmental events in plants and is important for the ripening of climacteric fruits [1,2]. Ethylene and carotenoid concentrations are relevant to this stud related to fruit ripening. Tomato (Lycopersicon esculentum Mill.) has been considered as an excellent model plant for the study of fruit ripening [3]. Several studies have investigated the molecular basis of fruit ripening. Naeem et al identified that SmCOP1 (CONSTITUTIVE PHOTOMORPHOGENIC) regulates ethylene biosynthesis and affects fruit ripening in tomato [4]. Studies have shown that ethylene triggers fruit ripening via the ethylene signaling pathway [5,6,7,8]

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