Phôi đánh dấu cụ thể không được phong phú trong protocorm và các mô PLBExpression of embryonic markers such as BBM, LEC1, FUS3, and ABI3s are not only enriched in zygotic and somatic embryos, some of their functions have also been demonstrated to be sufficient to establish embryonic fate during somatic embryogenesis (Braybrook and Harada, 2008; Smertenko and Bozhkov, 2014). Unlike somatic embryonic tissues observed in other plant species, PaLEC1 and PaFUS3 mRNAs were hardly detectable in protocorms and PLBs. The mRNAs of PaBBM and PaABI3L2 accumulated to low levels in 10-day-old protocorms and were hardly detectable in developing PLBs (Table 1 and Fig. 3B). The level of PaABIL1 mRNA was relatively high in abundance in developing protocorms and low inabundance in developing PLBs (Table 1 and Fig. 3B). In addition, mRNAs of the two embryonic marker genes, PaWRI1 and PaOLE1 whose functions are important for accumulation of storage reserves during the maturation phase of embryogenesis (Cernac and Benning, 2004; Hsieh and Huang, 2004) were expressed in very low abudance or undetectable in developing protocorms and PLBs. In situ hybridization also confirmed the lack of detectable PaLEC1 and PaBBM mRNA in developing PLBs (Fig. 4B and 4C). Therefore, expression of the embryonic marker genes was not correlated with initiation and development of PLBs. The ability of PaLEC1 and PaBBM to induce somatic embryogenesis was verified in Arabidopsis. Expression of the PaBBM and PaLEC1 proteins was verified by western blot analysis (Supplemental Fig. S5A). Overexpression of 35S:PaBBM324eGFP or 35S:eGFP- PaLEC1/35S:PaLEC1-eGFP (Fig. 5A and 5B) but not the empty vector (Supplemental Fig. S5B and S5C) caused ectopic production of cotyledons from somatic tissues. The embryonic specific genes such as Ole, Coleosin, Cruciferin 3 (CRU3), ABI3, and FUS3 were upregulated in somatic embryonic culture tissues of the transgenic plants (Fig. 5C and 5D). In addition, triacylglycerols that accumulate in embryonic tissues and stained intensely with the Sudan Red 7B, were also accumulated in embryonic-like tissues of 35S:PaLEC-eGFP and 35S:eGFP331
PaBBM transgenic lines (Fig. 5E). Moreover, overexpression of eGFP-PaLEC1 rescued lec1-1 desiccation tolerant phenotype (Fig. 5E), supporting that PaLEC1 is the functional ortholog of Arabidopsis LEC1. The 35S:eGFP-PaBBM construct failed to be generated and was therefore omitted from this study. In short, PaLEC1 and PaBBM genes are evolutionarily conserved and capable of inducing the somatic embryonic program.
In addition to surveying transcripti 337 onal factors that displayed enriched expression pattern during seed development, we also examined SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) whose expression has been shown to be associated with somatic embryogenesis (Schmidt et al., 1997; Hecht et al., 2001;
đang được dịch, vui lòng đợi..