Expression of genes associated with the biosynthetic pathways of abscisic acid, gibberellin, and ethylene during the germination of lettuce seeds

Abstract

ABSTRACT. Seed germination and dormancy are complex phenomena that are controlled by many genes and environmental factors. Such genes are indicated by phytohormones that interact with each other, and may cause dormancy or promote seed germination. The objective of this study was to investigate gene expression associated with the biosynthetic pathways of abscisic acid (ABA), gibberellic acid (GA), and ethylene (ET) in dormant and germinated lettuce seeds. The expressions of LsNCED, LsGA3ox1, and ACO-B were evaluated in germinating and dormant seeds from the cultivars Everglades, Babá de Verão, Verônica, Salinas, Colorado, and Regina 71. The expressions of LsNCED, LsGA3ox1, and ACO-B were related to the biosynthesis of ABA, GA, and ET, respectively; therefore, the presence of these substances depends on genotype. LsNCED expression only occurred in dormant seeds, and was connected to dormancy. LsGA3ox1expression only occurred in germinated seeds, and was connected to germination. The ACO-B gene was involved in ET biosynthesis, and was expressed differently in germinated and dormant seeds, depending on the genotype, indicating different functions for different characteristics. Furthermore, sensitivity to phytohormones appeared to be more important than the expression levels of LsNCED, LsGA3ox1, or ACO-B.

Physiological quality and gene expression during the development of habanero pepper (Capsicum chinense Jacquin) seeds

“…Contreras et al (2009) found high levels of endogenous ABA in lettuce (Lactuca sativa 'Tango') seeds during the intermediate and late developmental stages, which correspond to the point when seeds become tolerant to desiccation. Clemente et al (2013) also obtained the same results for lettuce seeds, in which the expression of the LsNCED gene was higher during the late developmental stages. A similar increase in gene expression was observed in this study for dried seeds harvested during the more advanced developmental stages; however, the relative values were lower.…”

Research Article GA3 and ABI3 gene expression in coffee seeds during maturation

“…In the present study, it was observed a negative relationship between CaABI 3 expression in the embryo and seed physiological quality, especially in seeds coming from harvested fruits in cherry stages, which had high germination values and low levels of CaABI 3 expression. This result was also observed in seeds of different species like Arabidopsis (Reyes & Chua, 2007), lettuce (Clemente et al, 2013), beet (Hermann et al, 2007) among others.…”

“…This indicates a repression mechanism of coffee seed germination in early stages of development (Eira et al, 2006). This mechanism can be controlled by several factors, such as the balance of abscisic acid and gibberellins levels, as observed in other species, maintaining both embryo and seed in the development mode (Eira et al, 2006, Hermann et al, 2007Kanno et al, 2010;Clemente, et al, 2013).…”

“…In coffee seeds GA 3 de novo biosynthesis is required for the elongation of embryo cells and endosperm breakage during germination (Silva et al 2005). The levels of ABA and GA in seeds are what determine dormancy or the capacity for germination (Clemente et al, 2015). According to Schuch et al (1990), coffee fruits undergo cell division 6-8 weeks after fertilization, but grow little in weight or volume during that period.…”

Thermoinhibition in parsley seeds

“…Clemente et al (2015) studied the expression of genes associated with biosynthetic pathways of abscisic acid, gibberellin and ethylene during lettuce seeds germination and found genes exclusive of dormant seeds.…”