The influence of ethylene perception on sex expression in melon (Cucumis melo L.) as assessed by expression of the mutant ethylene receptor, At-etr1-1, under the control of constitutive and floral targeted promoters

Abstract

Sexual diversity expressed by Curcurbitaceae species is a primary example of developmental plasticity in plants. Ethylene, which promotes femaleness (carpel development), plays a key role in sex determination. We sought to determine the critical location for ethylene perception in developing floral primodia. The dominant negative Arabidopsis ethylene response mutant gene, etr1-1, was introduced into melon (Cucumis melo L.) plants under control of the constitutive cauliflower mosaic virus (CaMV) 35S promoter, or floral-targeted Apetela3 (AP3) and Crab's Claw (CRC) promoters, which in Arabidopsis, promote expression in petal and stamen, and carpel and nectary primordia, respectively. Based on effects of exogenous ethylene, it was predicted that inhibition of ethylene perception by carpel primordia would inhibit carpel development. Constitutive expression of etr1-1 caused several phenotypes associated with ethylene insensitivity, verifying that etr1-1 inhibits ethylene perception in the heterologous melon system. Carpel-bearing bud production was essentially abolished in 35S::etr1-1 melons, providing direct demonstration of the requirement for ethylene perception for carpel development. CRC::etr1-1 plants, however, showed enhanced femaleness as manifested by earlier and increased number of carpel-bearing buds, and production of female (rather than bisexual) buds. Despite increased carpel-bearing bud formation, a greater proportion of the CRC::etr1-1 carpel-bearing buds aborted before anthesis. AP3::etr1-1 plants showed increased maleness by nearly exclusive staminate flower production, and poorly developed carpels in the rare bisexual flowers. These results indicate that ethylene perception by the stamen (or petal) primordia plays a critical role in promoting carpel development at the time of sex determination, while ethylene perception by the carpel is important for maturation of carpel-bearing flowers to anthesis.

Stamen development in Arabidopsis is arrested by organ-specific overexpression of a cucumber ethylene synthesis gene CsACO2

“…Our Wndings were consistent with the reports that increased endogenous ethylene production enhanced femaleness in transgenic melon (Cucumis melo L.), indicated by studies with 35S promoter driven ACS genes (Papadopoulou et al 2005) and a CRC promoter driven dominant negative etr1 gene (Little et al 2007). Papadopoulou et al (2005) and Little et al (2007) indicated ethylene eVects on carpel development in transgenic melon.…”

“…Papadopoulou et al (2005) and Little et al (2007) indicated ethylene eVects on carpel development in transgenic melon. However, we found no eVects of increased ethylene production on carpel development in transgenic P AP3 : CsACO2 Arabidopsis.…”

The effect of growth regulators on sex expression in melon (Cucumis melo L.)

“…Several investigations have shown that phytohormones are involved in changes of flower type, number and ratio of flowers of different sex types, modifications of flowering time and of other traits related to sex expression (Noguera et al 2005, Papadopoulou et al 2005, Stankovic et al 2005, Yamasaki et al 2005, Little et al 2007, Boualem et al 2008, Ouzounidou et al 2008, Martin et al 2009). Most of these studies were performed in cucumber, the model plant for studying sex expression in Cucurbitaceae.…”

Role of ethylene receptors during senescence and ripening in horticultural crops

“…Sex determination is another repercussion of altered ethylene perception in melon as reported by Little et al (2007). 145 The transgenic melon with At-etr1-1 gene resulting in reduced ethylene sensitivity showed change in sex expression.…”

“…145 The transgenic melon with At-etr1-1 gene resulting in reduced ethylene sensitivity showed change in sex expression. The expression of etr1-1 was studied under the influence of a constitutive promoter, CaMV35S and tissue specific inflorescence targeted Apetela3 (AP3) and Crab's Claw (CRC) promoters.…”