Developmental Abnormalities and Reduced Fruit Softening in Tomato Plants Expressing an Antisense Rab11 GTPase Gene

Abstract

A cDNA clone from tomato fruit encodes a protein with strong homology with the rab11/YPT3 class of small GTPases that is thought to be involved in the control of protein trafficking within cells. The gene, LeRab11a , showed a pattern consistent with a single copy in DNA gel blots. The corresponding mRNA was developmentally regulated during fruit ripening, and its expression was inhibited in several ripening mutants. Its reduced expression in the Never-ripe mutant indicates that it may be induced by ethylene in fruit. The ripening-induced expression in tissues that are undergoing cell wall loosening immediately suggests a possible role in trafficking of cell wall-modifying enzymes. The message also was produced in leaves and flowers but not in roots. Antisense transformation was used to generate a "mutant phenotype." Antisense fruit changed color as expected but failed to soften normally. This was accompanied by reduced levels of two cell wall hydrolases, pectinesterase and polygalacturonase. There were other phenotypic effects in the plants, including determinate growth, reduced apical dominance, branched inflorescences, abnormal floral structure, and ectopic shoots on the leaves. In some plants, ethylene production was reduced. These data suggest an alternative or additional role in exocytosis or endocytosis of homeotic proteins, hormone carriers, or receptors.

Overexpression of yeast spermidine synthase impacts ripening, senescence and decay symptoms in tomato

“…Our data indicate that the alteration of PA levels in ySpdSyn fruits did not affect the progression of ripening, unlike that observed with many of the mutant genotypes with an altered shelf life. It is possible that the extension of shelf life in ySpdSyn transgenic fruits is uncoupled from ripening, as was observed in the DFD and the LeRab11a antisense genotypes (Lu et al. , 2001; Saladié et al.…”

“…, 1973; Mutschler, 1984; Brummell and Harpster, 2001; Schuelter et al. , 2002; Giovannoni, 2004; Negi and Handa, 2008), transgenic plants with downregulated expression of LeRab11a , GTPase (Lu et al. , 2001) or N ‐glycans (Meli et al.…”

“…Fruits of transgenic plants in which the production or perception of ethylene is impaired lose coordination between ethylene‐dependent and ‐independent processes, and thus impact fruit quality (Giovannoni, 2002; Klee and Clark, 2002). In the same light, the prolonged shelf life of fruit from transgenic antisense LeRab11a lines with full color development was associated with undesirable phenotypes, including determinate growth, reduced apical dominance, branched inflorescences, abnormal floral structure and ectopic shoots on the leaves (Lu et al. , 2001).…”

“…, 2007). At the level of gene expression, a twofold decrease in the transcript levels of pectinesterase and polygalacturonase was found in LeRab11a antisense fruits (Lu et al. , 2001).…”

Conserved and Plant-Unique Mechanisms Regulating Plant Post-Golgi Traffic

“…For example, RABA2 and A3 are involved in cell plate formation (Chow et al, 2008), and RABA1 and RABA4 are required for normal tip growth of pollen tubes and root hairs (Preuss et al, 2004; de Graaf et al, 2005; Szumlanski and Nielsen, 2009). It has also been proposed that the function of RABA is associated with the biogenesis and degradation of the cell wall during fruit development (Zainal et al, 1996; Lu et al, 2001; Abbal et al, 2008; Lycett, 2008). …”