(214) Brassinosteroid-induced Femaleness in Cucumber and Relationship to Ethylene Production

Abstract

<jats:p>The cucurbit family is noted for diversity in sex expression phenotypes.</jats:p> <jats:p>Typically, a phase of male flowers precedes the appearance of female or hermaphrodite flowers. Sex determination of individual flowers is regulated by genetic, environmental, and hormonal factors. Ethylene, auxins, and gibberellins all influence flower sex, with ethylene, which promotes femaleness, playing a predominant role. In this study, we tested whether brassinosteroids, a more recently identified class of plant hormones, also influence cucurbit sex expression. Applied epi-brassinolide (epi-BL) caused a significant decrease in time of appearance of the first female flower on monoecious cucumber plants, and increased total female flowers on the main stem. Increasing concentrations had a stronger effect. Of the three species tested, cucumber, melon, and zucchini, cucumber was the most responsive. Application of epi-BL also caused an increase in ethylene production by cucumber and zucchini seedlings, suggesting that the BR effect may be mediated by ethylene. To investigate the possible relationship between BR and ethylene on sex expression, we identified the concentration of ethephon (5 ppm) that caused an increase in ethylene production comparable to that induced by 10 μ<jats:sc>m</jats:sc> epi-BL (about two-fold). Treatment with 5 ppm ethephon was sufficient to increase femaleness of cucumber plants, but not zucchini plants, suggesting that the difference in response to epi-BL may reflect differences in sensitivity to ethylene. Collectively, our results indicate that application of brassinosteroids to cucumber cause earlier and increased female flower production, and that the effects may be mediated, at least in part, by brassinosteroid-induced increased production of ethylene.</jats:p>

RNA‐Seq Transcriptome Profiling Reveals Differentially Expressed Genes Involved in Sex Expression in Melon

“…The role of BR in sex determination of cucurbit species is not clear, but it is well known that it induces the production of ethylene in several plant species (Arteca and Arteca, 2008), including cucurbits (Guo et al, 2010). Thus, it is suggested that the effect of brassinosteroids on sex expression in cucumber is also mediated by ethylene (Papadopoulou and Grumet, 2005). In Cucumis pepo, BR may regulate the induction of carpellate development, although this regulation is genotype dependent (Golenberg and West, 2013).…”

Transcriptome profile analysis of floral sex determination in cucumber

“…The application of brassinosteroids in cucumber causes earlier and increased female flower production, and the effects may be mediated, at least in part, by the brassinosteroid-induced production of ethylene (Papadopoulou and Grumet, 2005). TLP is a potential substrate of brassinosteroidinsensitive 1, which can regulate certain biochemical activities near the plasma membrane to control plant growth (Nam and Li, 2004).…”

Modified plant architecture to enhance crop disease control: genetic control and possible value of upright fruit position in cucumber

“…BR mutations in Arabidopsis are associated with abnormal vascular development with increased phloem differentiation relative to xylem (Cano-Delgado et al 2004). We also have observed effects of BR treatment leading to distorted vascular development in cucumber (Papadopoulou and Grumet 2005). However, vascular bundles in PI308916 appeared normal; the disorganized cellular arrangement in PI308916 was associated with the interfascicular cortex region.…”