GA3 induces expression of E2F-like genes and CDKA during in vitro germination of zygotic embryos of Cocos nucifera (L.)

Abstract

Previous reports have demonstrated that gibberellins promote seed germination, including in vitro germination of zygotic embryos of coconut. Genes that control the cell cycle seem to play important roles during germination. In this study, complete full-length sequences of two E2F-like genes, CnE2F1 and CnE2F2, were obtained. Deduced amino acid sequences of both genes showed conserved domains characteristic of E2F genes. Both genes showed high homology with Arabidopsis thaliana E2Fa and E2Fb, which are transcriptional activators. The expression profiles of CnE2F genes were evaluated in in vitro zygotic embryos with or without gibberellic acid. In control embryos, expression of CnE2F1 showed a peak at day 2, and, gradually this dropped to similar levels as those at day 0. Gibberellic acid (GA3) treatment promoted expression at day 2, higher than that of the control. For CnE2F2, peak expression was detected at day 8 of culture. However, with GA treatment, CnE2F2 expression profile increased by day 2. The expression profile of a cyclin-dependent kinase (CnCDKA), another gene related to the cell cycle control, was also studied. In control embryos, expression of this gene showed two peaks at days 2 and 8, compared with day 0. A different profile was shown with GA treatment. In general, major changes in expression profiles were observed from days 2-8 when morphological changes in zygotic embryos were not yet observed.

Temperature and GA3 on ROS and cytogenetic stability during in vitro cultivation of strelitzia zygotic embryos

“…After 60 days, for the embryos cultivated in medium with 20 µM GA 3 , a germination percentage of 72% was observed, whereas in the absence of this growth regulator, the germination percentage was only 41% (Figure 1). Similar results were found for Cocos nucifera (L.), where the use of GA 3 increased the germination of zygotic embryos by 50% (Montero-Cortés et al, 2011).…”

“…For some species, supplementation of the germination medium with GA 3 has been used since this compound regulates the germination of seeds and zygotic embryos. The in vitro germination of some species, such as Maclura tinctoria, Cocos nucifera, and Syagrus coronata, has been increased by supplying the medium with GA 3 (Gomes et al, 2010;Medeiros et al, 2015;Montero-Cortés et al, 2011). This growth regulator could be important for cell growth and elongation, leaf expansion and photosynthetic processes, as well as for the activity of important metabolic enzymes, such as nitrate reductase (Gupta;Chakrabarty, 2013, Bezerra et al, 2019.…”