An Expansin Gene Expressed in Ripening Strawberry Fruit

• Published in: Plant physiology (Bethesda) 1999-12, Vol.121 (4), p.1273-1279
• Main Authors: Pedro Marcos Civello, Ann L. T. Powell, Adnan Sabehat, Bennett, Alan B.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Amino Acid Sequence; Auxins; Biological and medical sciences; Cell walls; Complementary DNA; DNA, Complementary; Economic plant physiology; Ethylenes - pharmacology; expansin; FaExp2 gene; Fragaria; Fructification and ripening; Fructification, ripening. Postharvest physiology; Fruit - drug effects; Fruit - genetics; Fruit - physiology; Fruits; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Gene Library; Growth and Development; Indoleacetic Acids - pharmacology; LeExp1 gene; Messenger RNA; Molecular Sequence Data; Plant cells; Plant Growth Regulators - pharmacology; Plant physiology and development; Plant Proteins - chemistry; Plant Proteins - genetics; Plants; Ripening; RNA; Space life sciences; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.121.4.1273

Tissue softening accompanies the ripening of many fruit and initiates the processes of irreversible deterioration. Expansins are plant cell wall proteins proposed to disrupt hydrogen bonds within the cell wall polymer matrix. Expression of specific expansin genes has been observed in tomato (Lycopersicon esculentum) meristems, expanding tissues, and ripening fruit. It has been proposed that a tomato ripening-regulated might contribute to cell wall polymer disassembly and fruit softening by increasing the accessibility of specific cell wall polymers to hydrolase action. To assess whether ripening-regulated expansins are present in all ripening fruit, we examined expansin gene expression in strawberry (Fragaria × ananassa Duch.). Strawberry differs significantly from tomato in that the fruit is derived from receptacle rather than ovary tissue and strawberry is non-climacteric. A full-length cDNA encoding a ripening-regulated expansin, FaExp2, was isolated from strawberry fruit. The deduced amino acid sequence of FaExp2 is most closely related to an expansin expressed in early tomato development and to expansins expressed in apricot fruit rather than the previously identified tomato ripening-regulated expansin, LeExp1. Nearly all previously identified ripening-regulated genes in strawberry are negatively regulated by auxin. Surprisingly, FaExp2 expression was largely unaffected by auxin. Overall, our results suggest that expansins are a common component of ripening and that non-climacteric signals other than auxin may coordinate the onset of ripening in strawberry.