A putative positive feedback regulation mechanism in CsACS2 expression suggests a modified model for sex determination in cucumber (Cucumis sativus L.)

Abstract

It is well established that the plant hormone ethylene plays a key role in cucumber sex determination. Since the unisexual control gene M was cloned and shown to encode an ethylene synthase, instead of an ethylene receptor, the ‘one-hormone hypothesis’, which was used to explain the cucumber sex phenotype, has been challenged. Here, the physiological function of CsACS2 (the gene encoded by the M locus) was studied using the transgenic tobacco system. The results indicated that overexpression of CsACS2 increased ethylene production in the tobacco plant, and the native cucumber promoter had no activity in transgenic tobacco (PM). However, when PM plants were treated with exogenous ethylene, CsACS2 expression could be detected. In cucumber, ethylene treatment could also induce transcription of CsACS2, while inhibition of ethylene action reduced the expression level. These findings suggest a positive feedback regulation mechanism for CsACS2, and a modified ‘one-hormone hypothesis’ for sex determination in cucumber is proposed.

CORRECTED VERSION Identification and characterization of genes connected with flower morphogenesis in cucumber

“…Brassinosteroids are plant hormones that increase ethylene production and also interact with each other (Hansen et al, 2010). Ethylene is regarded as essential in sex determination in cucumber, (Li et al, 2012). The F and M genes responsible for sex determination are the CsACS1G and CsACS2 genes, respectively.…”

“…The role of plant hormone ethylene in cucumber sex determination is well established (Li et al, 2012). Cucumber gender can be influenced by many environmental factors, including photoperiod, temperature, and plant hormones such as ethylene, auxin, and gibberellic acid (Atsmon et al, 1968;Perl-Treves, 1999;Yamasaki et al, 2005).…”

“…Cucumber gender can be influenced by many environmental factors, including photoperiod, temperature, and plant hormones such as ethylene, auxin, and gibberellic acid (Atsmon et al, 1968;Perl-Treves, 1999;Yamasaki et al, 2005). The expression of the CsACS2 gene is correlated with ethylene production and which can also induce the expression of the CsACS2 gene; therefore suggesting a positive feedback (Li et al, 2012). Identification of more mutations in the cucumber sex expression pathway and cloning of those genes may reveal more information for better understanding of the process (Li et al, 2012).…”

“…The expression of the CsACS2 gene is correlated with ethylene production and which can also induce the expression of the CsACS2 gene; therefore suggesting a positive feedback (Li et al, 2012). Identification of more mutations in the cucumber sex expression pathway and cloning of those genes may reveal more information for better understanding of the process (Li et al, 2012).…”

Flower Development in Walnut: Altering the Flowering Pattern by Gibberellic Acid Application

“…On the other hand, low temperatures and short-day conditions induce the development of female flowers in cucumber plants (Li et al, 2012). The application of plant growth regulators (PGRs) have been suggested as a useful alternative to solving problems related to flowering in plants (Ghani et al, 2013).…”