Genetic and Hormonal Regulation of Growth, Flowering, and Sex Expression in Plants

Abstract

The interaction of the genetic and hormonal regulation of growth, flowering, and sex expression in plants is discussed. The genetic control ofthese processes is characterized, and data on their hormonal regulation are supplied. The interaction of genetic and hormonal regulation is considered with reference to tall-growing and genetic dwarf forms of the pea and wheat plants. It is shown that in the dwarf forms of the pea plant and in many other varieties, growth stimulation in response to treatment with the phytohormone gibberellic acid is clearly manifested and the expression of genetic dwarfism is eliminated, whereas in dwarf wheats it is expressed only slightly, if at all. At the same time both tall-growing and dwarf forms of both pea and wheat show a clearly defined growth retardation response to treatment with the growth inhibitor, abscisic acid, which causes the expression of physiological dwarfism. The short-and long-day characteristics of the photoperiodic response of plants are described as genetically controlled features, and data are given on the induction of flowering of a long-day variety coneflower grown under short-day conditions with the aid of gibberellins extracted from leaves of long-day vegetative plants of short-day Mammoth tobacco. Data are also supplied on the induction of flowering of a short-day variety, red-leaved goosefoot, grown under continuous light with the aid of metabolites extracted from leaves of the same Mammoth tobacco plants flowering under short-day conditions. This demonstrates the possibility of hormonal regulation ofthe genetically controlled long-day and short-day characteristics in photoperiodically sensitive plants. Genetic and hormonal regulation of sex expression in two dioecious plants, hemp and spinach, is discussed. It is shown that sex expression in these plants is regulated by gibberellins which are synthesized in leaves and cause male sex expression and by cytokinins which are synthesized in the roots and cause female sex expression. These data indicate that sex expression in dioecious plants is the result of interaction between the genetic apparatus and phytohormones.

Comparative Transcriptome Analysis between Gynoecious and Monoecious Plants Identifies Regulatory Networks Controlling Sex Determination in Jatropha curcas

“…The phytohormones auxin, BR, CK, ETH, GA, and JA influence sex differentiation in flowering plants (Louis and Durand, 1978; Chailakhyan, 1979; Durand and Durand, 1984; Irish and Nelson, 1989; Perl-Treves, 1999). Our results showed that the expression of some key genes involved in ABA, auxin, CK, ETH, GA, and JA biosynthesis pathways was significantly changed during inflorescence development and sex expression in J. curcas , suggesting that these hormones may participate in these processes.…”

“…The exogenous application of auxin, BR, cytokinin (CK), ETH, GA, JA, and their inhibitors affects sex expression in flowering plants (Louis and Durand, 1978; Chailakhyan, 1979; Durand and Durand, 1984; Irish and Nelson, 1989; Perl-Treves, 1999), and some of them have opposing effects on sex determination in different plant lineages (Yamasaki et al, 2005). Environmental cues such as temperature, photoperiod, nutrition, drought, pH, and seasonality also effect sex determination in many species (Korpelainen, 1998; Field et al, 2013; Golenberg and West, 2013).…”

Genetics of sex determination in flowering plants

“…Environmental factors such as light intensity, day length, temperature, and mineral nutrition affect sex of many monoecious and dioecious species including maize, hemp, cucumber (Cucumis satzuis), and spinach (Chailakhyan, 1979;Frankel and Galun, 19771, but the effects are species-specific. Plant hormones can also affect the sex of flowers in monoecious and dioecious species.…”

“…However, no hormone has a common effect on all unisexual species. For example, cytokinins are feminizing in spinach, hemp and mercury (Chailakhyan 1979;Durand 1969) but they have no apparent effect on other species, such as cucumber and maize (Frankel and Galun, 1977). Furthermore, the same hormone often shows opposite effects on different species.…”

Influence of Environment on the Floral Sex Ratio of Monoecious Plants

“…The precise mechanism which controls the allocation of resources to one or the other sexual function has not been thoroughly described. However, we do know that auxins, gibberellins, and cytokinins play important roles (Heslop-Harrison, 1972;Chailakhyan, 1979). Moreover these hormones are responsive to the environmental conditions (see Vaadia, 1965, 1970;Itai et aI., 1968Itai et aI., , 1973Burrows and Carr, 1969;Torrey, 1976).…”