The Genepat-2, Which Induces Natural Parthenocarpy, Alters the Gibberellin Content in Unpollinated Tomato Ovaries

Abstract

We investigated the role of gibberellins (GAs) in the effect of pat-2, a recessive mutation that induces facultative parthenocarpic fruit development in tomato (Lycopersicon esculentum Mill.) using near-isogenic lines with two different genetic backgrounds. Unpollinated wild-type Madrigal (MA/wt) and Cuarenteno (CU/wt) ovaries degenerated, but GA 3 application induced parthenocarpic fruit growth. On the contrary, parthenocarpic growth of MA/pat-2 and CU/pat-2 fruits, which occurs in the absence of pollination and hormone application, was not affected by GA 3 . Pollinated MA/wt and parthenocarpic MA/pat-2 ovary development was negated by paclobutrazol, and this inhibitory effect was counteracted by GA 3 . The main GAs of the early-13-hydroxylation pathway (GA 1 , GA 3 , GA 8 , GA 19 , GA 20 , GA 29 , GA 44 , GA 53 , and, tentatively, GA 81 ) and two GAs of the non-13-hydroxylation pathway (GA 9 and GA 34 ) were identified in MA/wt ovaries by gas chromatography-selected ion monitoring. GAs were quantified in unpollinated ovaries at flower bud, pre-anthesis, and anthesis. In unpollinated MA/pat-2 and CU/pat-2 ovaries, the GA 20 content was much higher (up to 160 times higher) and the GA 19 content was lower than in the corresponding non-parthenocarpic ovaries. The application of an inhibitor of 2-oxoglutarate-dependent dioxygenases suggested that GA 20 is not active per se. The pat-2 mutation may increase GA 20-oxidase activity in unpollinated ovaries, leading to a higher synthesis of GA 20 , the precursor of an active GA.

RNA Interference Silencing of Chalcone Synthase, the First Step in the Flavonoid Biosynthesis Pathway, Leads to Parthenocarpic Tomato Fruits

“…In contrast to the Chs RNAi tomato, parthenocarpic fruit development of all these pat mutants is independent of pollination. At least some of these mutants (pat2, pat3, and pat4) contain increased GA levels in their parthenocarpic fruits, suggesting that the ability of these mutants to develop parthenocarpic fruits is due to alterations in GA metabolism (Fos et al, 2000(Fos et al, , 2001. Clearly, fruit development is controlled by complex processes, including multiple plant growth hormones and cross talk between regulatory plant hormones.…”

Abscisic acid levels in tomato ovaries are regulated by LeNCED1 and SlCYP707A1

“…The resulting parthenocarpic fruit growth is a clear demonstration of the importance of hormones in fruit initiation and development. There are a number of parthenocarpic tomato mutants, such as pat, pat2 and pat3/4, in which it was shown that the GA content and/or GA biosynthesis were increased signiWcantly (Mazzucato et al 1998;Fos et al 2000Fos et al , 2001Olimpieri et al 2007). Furthermore, overexpression of the iaaM gene, which encodes an enzyme involved in auxin biosynthesis, also induced parthenocarpic fruit development in tomato and many other species (Rotino et al 1997;Mezzetti et al 2004).…”

Effect of Priming With Gibberellin On Germination and Expression of Ga Biosynthesis Gene Of Tomato (Solanum Lycopersicum L.) Seedlings Under Salt Stress

“…In tomato, the GA biosynthetic genes CPS, GA20ox, GA3ox, GA2ox and GA4 have been isolated (Rebers et al, 1999 andSerrani et al, 2007). The process of fruit set in tomato involves GA1 as the bioactive GA molecule and the early 13-hydroxylation pathway as the primary metabolic pathway (Serrani et al, 2007 andFos et al, 2000). Pollination mediates fruit set through GA biosynthesis, which is mainly achieved by the up-regulation of GA20ox (Serrani at al., 2007).…”