A new class of regulatory genes underlying the cause of pear-shaped tomato fruit.

A common, recurring theme in domesticated plants is the occurrence of pear-shaped fruit. A major quantitative trait locus (termed ovate) controlling the transition from round to pear-shaped fruit has been cloned from tomato. OVATE is expressed early in flower and fruit development and encodes a previously uncharacterized, hydrophilic protein with a putative bipartite nuclear localization signal, Von Willebrand factor type C domains, and an approximately equal 70-aa C-terminal domain conserved in tomato, Arabidopsis, and rice. A single mutation, leading to a premature stop codon, causes the transition of tomato fruit from round- to pear-shaped. Moreover, ectopic, transgenic expression of OVATE unevenly reduces the size of floral organs and leaflets, suggesting that OVATE represents a previously uncharacterized class of negative regulatory proteins important in plant development.