Multiple evidence for the role of an <it>Ovate</it>-like gene in determining fruit shape in pepper

• Main Authors: Tsaftaris Athanasios S, Darzentas Nikos, Pasentsis Konstantinos, Tsaballa Aphrodite
• Format: Article
• Language: English
• Published: BMC 2011-03-01
• Series: BMC Plant Biology
• Online Access: http://www.biomedcentral.com/1471-2229/11/46

<p>Abstract</p> <p>Background</p> <p>Grafting is a widely used technique contributing to sustainable and ecological production of many vegetables, but important fruit quality characters such as taste, aroma, texture and shape are known for years to be affected by grafting in important vegetables species including pepper. From all the characters affected, fruit shape is the most easily observed and measured. From research in tomato, fruit shape is known to be controlled by many QTLs but only few of them have larger effect on fruit shape variance. In this study we used pepper cultivars with different fruit shape to study the role of a pepper <it>Ovate</it>-like gene, <it>CaOvate</it>, which encodes a negative regulator protein that brings significant changes in tomato fruit shape.</p> <p>Results</p> <p>We successfully cloned and characterized <it>Ovate</it>-like genes (designated as <it>CaOvate</it>) from two pepper cultivars of different fruit shape, cv. "Mytilini Round" and cv. "Piperaki Long", hereafter referred to as cv. "Round" and cv. "Long" after the shape of their mature fruits. The <it>CaOvate </it>consensus contains a 1008-bp ORF, encodes a 335 amino-acid polypeptide, shares 63% identity with the tomato OVATE protein and exhibits high similarity with OVATE sequences from other Solanaceae species, all placed in the same protein subfamily as outlined by expert sequence analysis. No significant structural differences were detected between the <it>CaOvate </it>genes obtained from the two cultivars. However, relative quantitative expression analysis showed that the expression of <it>CaOvate </it>followed a different developmental profile between the two cultivars, being higher in cv. "Round". Furthermore, down-regulation of <it>CaOvate </it>through VIGS in cv. "Round" changes its fruit to a more oblong form indicating that <it>CaOvate </it>is indeed involved in determining fruit shape in pepper, perhaps by negatively affecting the expression of its target gene, <it>CaGA20ox1</it>, also studied in this work.</p> <p>Conclusions</p> <p>Herein, we clone, characterize and study <it>CaOvate </it>and <it>CaGA20ox1 </it>genes, very likely involved in shaping pepper fruit. The oblong phenotype of the fruits in a plant of cv. "Round", where we observed a significant reduction in the expression levels of <it>CaOvate</it>, resembled the change in shape that takes place by grafting the round-fruited cultivar cv. "Round" onto the long-fruited pepper cultivar cv. "Long". Understanding the role of <it>CaOvate </it>and <it>CaGA20ox1</it>, as well as of other genes like <it>Sun </it>also involved in controlling fruit shape in Solanaceae plants like tomato, pave the way to better understand the molecular mechanisms involved in controlling fruit shape in Solanaceae plants in general, and pepper in particular, as well as the changes in fruit quality induced after grafting and perhaps the ways to mitigate them.</p>