Cloning and characterization of four differentially expressed cDNAs encoding NFYA homologs involved in responses to ABA during somatic embryogenesis in Japanese larch (Larix leptolepis)
2014
Zhang, Li-feng | Li, Wan-feng | Xu, Hai-yan | Qi, Li-wang | Han, Su-ying
In this study, four nuclear transcription factor Y subunit alpha (NFYA) homologous genes, LaNFYA1, LaNFYA2, LaNFYA3, and LaNFYA4, were isolated from Japanese larch (Larix leptolepis). The deduced amino acid sequences of the LaNFYAs harbored a highly conserved core region consisting of two functional domains: a subunit association domain and a DNA-binding homeodomain. Further analysis showed that miR169 target sequences were present in the 3′ end of all four LaNFYA mRNA sequences. A transient expression analysis of the LaNFYA-GFP fusion proteins in tobacco leaf epidermal cells revealed that the LaNFYA proteins were localized in the nucleus. An analysis of tissue expression levels of the LaNFYAs showed that expression was highest in the stems and lowest in the needles, demonstrating a pattern of temporal- and spatial-specific expression. Their mRNA accumulation patterns during somatic embryogenesis, and the effects of abscisic acid (ABA) on their transcript levels and somatic embryo maturation were investigated. The results showed that the transcripts of the four genes gradually increased and peaked at 7 days, followed by a decline as the somatic embryos matured, and that the removal of the ABA treatment did not affect the mRNA abundance of LaNFYA1, LaNFYA2, and LaNFYA3 during the first 14 days, but up-regulated the abundance of LaNFYA4 mRNA. We concluded that LaNFYAs may be involved with the early determination and maturation of the somatic embryo, which is regulated by responses to ABA and miR169. These results provide new insights into the regulatory mechanisms of somatic embryogenesis.
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