Silencing of DELLA induces facultative parthenocarpy in tomato fruits

Abstract

SummaryDELLA proteins are plant nuclear factors that restrain growth and proliferation in response to hormonal signals. The effects of the manipulation of the DELLA pathway in the making of a berry-like fruit were investigated. The expression of the Arabidopsis thaliana gain-of-function DELLA allele Atgai del in tomato (Solanum lycopersicum L.) produced partially sterile dwarf plants and compacted influorescences, as expected for a constitutively activated growth repressor. In contrast, antisense silencing of the single endogenous tomato DELLA gene homologue (SlDELLA) produced slender-like plants with elongated flower trusses. Interestingly, the depletion of SlDELLA in tomato was sufficient to overcome the growth arrest normally imposed on the ovary at anthesis, resulting in parthenocarpic fruits in the absence of pollination. Antisense SlDELLA-engineered fruits were smaller in size and elongated in shape compared with wild type. Cell number estimations showed that fruit set, resulting from reduced SlDELLA expression, arose from activated cell elongation at the longitudinal and lateral axes of the fruit pericarp, bypassing phase-II (post-pollination) cell divisions. Parthenocarpy caused by SlDELLA depletion is facultative, as hand pollination restored wild-type fruit phenotype. This indicates that fertilization-associated SlDELLA-independent signals are operational in ovary-fruit transitions. SlDELLA was also found to restrain growth in other reproductive structures, affecting style elongation, stylar hair primordial growth and stigma development.

Genetic Analysis Reveals That C19-GA 2-Oxidation Is a Major Gibberellin Inactivation Pathway inArabidopsis

“…However, the ga2ox quintuple shows parthenocarpic pistil elongation ( Figure 6D), largely due to the loss of GA2ox2 (Figure 6E), which appears to start before flower opening, as in many cases the pistil impacts against the petals and sepals causing it to bend ( Figure 6C). It has recently been shown that the pistils also overelongate prematurely in tomato (Solanum lycopersicum) plants with constitutive GA signaling (Marti et al, 2007).…”

A Visual Reporter System for Virus-Induced Gene Silencing in Tomato Fruit Based on Anthocyanin Accumulation

“…The quality of VIGS response in each line was evaluated from the percentage of fruit agroinjected with the pTRV2_DR construct that developed red sectors and the size of the red sectors with respect to the total fruit surface. Plants were grown in a greenhouse supplemented with artificial light as described earlier (Marti et al, 2007).…”

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

“…For instance, it was shown that expression of a GA 20-oxidase gene was induced by pollination in tomato (Rebers et al 1999;Serrani et al 2007), and the importance of SlDELLA, which represses GA signaling and tomato fruit set, has also been demonstrated (Marti et al 2007). In additional, IAA9 and ARF8, both transcriptional regulators of the auxin response, were shown to be part of an important signal for fruit set (Wang et al 2005;Goetz et al 2007).…”