These results were in agreement with the previous report. Similarities and differences in the phenotype of ectopic expression of LEC1 and LEC2 in Arabidopsis and tobacco indicated their partially overlapping but not identical roles in somatic AbMole Succinylsulfathiazole embryo induction between LEC1 and LEC2, as well as in different species. Our results showed that LEC2 could be a better candidate for improving the regeneration ability of crop plants. Studies showed that LEC1 and LEC2 cause accumulation of seed storage reserves and LEC2 directly induce genes involved in maturation processes before formation of somatic embryos. Our study proved that many genes in seed maturation phase are activated by ectopic expression of LEC2 in tobacco. Many genes involved in biosynthesis of fatty acid and steroid, were also up-regulated, consistent with the fact that LEC1 and LEC2 increase fatty acid and lipid accumulation. LEC2 induced the expression of SUS2, a sucrose synthase gene, in maturation phase. Taken together, our results suggested that ectopic expression of AtLEC2 induces maturation processes in transgenic tobacco. Our results showed that many regulatory factors involved in embryo development and somatic embryogenesis, including MADS-box protein 9, L1L, and SERK1, were activated by LEC2. MADS9 belonging to AGL15 subgroup of the MADS box family, expressed mainly during embryogenesis. Constitutive expression of AGL15 enhances competence of somatic embryo formation from the shoot apical meristems. Braybrook showed that LEC2 could induce the expression of FUSCA3 and ABI3 and could directly regulate AGL15. LEC2, FUS3 and ABI3 were found as direct target genes of AGL15. Our results suggested that LEC2 activated MADS9, one member of the AGL15 subgroup. However, expression changes of FUS3 and ABI3 were not observed in LEC2 transgenic tobacco. LEC2 might regulate somatic embryogenesis through FUS3 and ABI3 indirectly in ways which remains unknown. L1L plays distinct roles from LEC1 but over expression of L1L could rescue lec1 mutant. Ectopic expression of LEC2 increase expression of LEC1, and LEC2 could be induced by LEC1. Our results demonstrated that ectopic expression of LEC2 could up-regulate L1L in transgenic tobacco. It was suggested that L1L may play key roles in LEC2 inducing somatic embryogenesis. SERK1 is a key factor promoting vegetative-to-embryonic transition and over expression of SERK1 increases somatic formation. SERK1 was considered as a marker of embryonic cells. Up-regulation of SERK1 in LEC2 transgenic tobacco provided further evidence for its roles in promoting embryogenesis. LEC2 activated several transcription factors including NAC, AP2 and GRAS gene family. NAC proteins play diverse roles in a wide range of plant developmental processes, such as embryo development, shoot apical meristem development, lateral root development, and hormone signaling. HAM, a member of GRAS family, regulates both shoot and root meristems.