Involvement of ethylene biosynthesis and signalling in fruit set and early fruit development in zucchini squash (Cucurbita pepoL.)

Abstract

BackgroundWe have identified a kind of parthenocarpy in zucchini squash which is associated with an incomplete andromonoecy, i.e. a partial conversion of female into bisexual flowers. Given that andromonoecy in this and other cucurbit species is caused by a reduction of ethylene production in the female flower, the associated parthenocarpic development of the fruit suggested the involvement of ethylene in fruit set and early fruit development.ResultsWe have compared the production of ethylene as well as the expression of 13 ethylene biosynthesis and signalling genes in pollinated and unpollinated ovaries/fruits of two cultivars, one of which is parthenocarpic (Cavili), while the other is non-parthenocarpic (Tosca). In the latter, unpollinated ovaries show an induction of ethylene biosynthesis and ethylene signal transduction pathway genes three days after anthesis, which is concomitant with the initiation of fruit abortion and senescence. Fruit set and early fruit development in pollinated flowers of both cultivars and unpollinated flowers of Cavili is coupled with low ethylene biosynthesis and signalling, which would also explain the partial andromonoecy in the parthenocarpic genotype. The reduction of ethylene production in the ovary cosegregates with parthenocarpy and partial andromonoecy in the selfing progeny of Cavili. Moreover, the induction of ethylene in anthesis (by ethephon treatments) reduced the percentage of bisexual parthenocarpic flowers in Cavili, while the inhibition of ethylene biosynthesis or response (by AVG and STS treatments) induces not only andromonoecy but also the parthenocarpic development of the fruit in both cultivars.ConclusionsResults demonstrate that a reduction of ethylene production or signalling in the zucchini flower is able to induce fruit set and early fruit development, and therefore that ethylene is actively involved in fruit set and early fruit development. Auxin and TIBA treatments, inducing fruit set and early fruit development in this species, also inhibit ethylene production and the expression of ethylene biosynthesis and response genes. A model is presented that discusses the crosstalk between ethylene and auxin in the control of fruit set and early fruit development in zucchini squash.

Roles of Ethylene Production and Ethylene Receptor Expression in Regulating Apple Fruitlet Abscission

“…Nevertheless, it is known to decline just after fruit set in several species (Vriezen et al, 2008;Wang et al, 2009;Martínez et al, 2013), most likely along with the availability of its immediate precursor 1-aminocyclopropane-1-carboxylate (A. Botton, unpublished data). According to the data provided by the meteorological station located in the experimental orchards, during the 5 d preceding the thinning treatment (10-14 DAPF), mean and maximum temperatures in 2009 were 3.3°C (11.2°C versus 14.5°C) and 6.2°C (15°C versus 21.2°C) lower than in 2008, respectively.…”

The Zinc Finger Transcription Factor SlZFP2 Negatively Regulates Abscisic Acid Biosynthesis and Fruit Ripening in Tomato

“…Accumulating data from tomato and other plant species has suggested that ethylene and ABA might play a role in fruit set, because their production decreases dramatically right after pollination (Vriezen et al, 2008;Nitsch et al, 2009;Pascual et al, 2009;Wang et al, 2009;CarbonellBejerano et al, 2011;Martínez et al, 2013). Our RNA-seq data suggested that the problematic fruit set in the SlZFP2 RNAi lines seems to result from the disturbed action of multiple hormones, because the expression of many genes involved in the biosynthesis and/or perception of auxin, cytokinin, GA, ABA, and ethylene was affected.…”

Courgette Production: Pollination Demand, Supply, and Value

“…Nonetheless, it is of industrial and ecological interest that 56% of nonpollinated flowers were still able to reach marketable size and shape without any pollination at all. This is owing to the natural parthenocarpic tendency of courgettes, previously observed in Tosca (Mart ınez et al 2013) and other varieties (Robinson and Reiners 1999). However, Mart ınez et al (2013) concluded that Tosca was not truly parthenocarpic, as fruits consistently showed a burst in ethylene around 3 d after anthesis, which is thought to cause early fruit abortion in nonpollinated flowers.…”

“…For example, 22 out of the 33 summer squash varieties have been shown to set fruit without pollination (Robinson and Reiners 1999). Likewise, fruit set without pollination has also been observed in cucumber (Kushnereva 2008), watermelon (Sedgley et al 1977), and additional varieties of summer squash (Kurtar 2003;Mart ınez et al 2013Mart ınez et al , 2014. This type of fruit set, without pollination and therefore fertilization, is parthenocarpy.…”