Characterization and expression analysis of somatic embryogenesis receptor-like kinase genes from Phalaenopsis

Abstract

ABSTRACT. Somatic embryogenesis receptor-like kinase (SERK) genes have been found to be involved in the somatic embryogenesis of several plant species. We identified and characterized 5 PhSERK genes in the Phalaenopsis orchid. The amino acid sequences of PhSERKs and other SERK proteins are highly conserved, with the highest homology observed in the leucine-rich repeat-receptor-like kinase domain. All 5 PhSERKs were expressed in all Phalaenopsis organs examined (root, leaf, shoot apical meristem, and flower), with the strongest expression, particularly for PhSERK1 and 3, in the shoot apical meristem of mature plants. Expression of all PhSERKs was downregulated during early floral bud development and was upregulated gradually until the semiopen flower stage was reached. All 5 PhSERKs were expressed during both seed germination and protocorm-like-body (PLB) development. In germinated seeds, quantitative real-time PCR revealed upregulation of all PhSERKs except PhSERK4 at 1 week and downregulation after 4 weeks. The 5 PhSERKs were differentially expressed in the early stage Characterization of genes from Phalaenopsis of PLB development and maintained substantial levels during PLB formation, with PhSERK1 and 5 upregulated 1 week after culture and PhSERK2, 3, and 4 downregulated over this period. Because physical wounding of PLB stimulates secondary PLB formation, the PhSERK5 expression peak at week 3 coincided with visible and fully developed secondary PLBs. PhSERK5 may be important in PLB induction and subsequent development. Our PhSERK expression analysis revealed that these genes have a broad role during orchid plant development.

Ectopic expression of the Coffea canephora SERK1 homolog‐induced differential transcription of genes involved in auxin metabolism and in the developmental control of embryogenesis

“…Evaluation of CcSERK1 gene expression demonstrated basal transcription levels in almost every organ of the plant, but the highest ratio was detected in the shoot apical meristem. A similar result was obtained in the Phalaenopsis orchid , where expression of the SERK1 homolog is higher in shoot apical meristem than in any other tissue (Huang et al ). With respect to zygotic embryogenesis, the amount of CcSERK1 transcript increased twice during flower development; the first increase occurred 1 day after anthesis, and the second increase in CcSERK1 transcription occurred just after pollination, which occurs between days four and six after anthesis in coffee flowers (León ).…”

Protocorms and Protocorm-Like Bodies Are Molecularly Distinct from Zygotic Embryonic Tissues in Phalaenopsis aphrodite

“…Three previously reported SERK-like genes, PaSERK1, PaSERK2, and PaSERK5 (Huang et al, 2014), also were present in our transcriptome database. However, the expression of PaSERK1, PaSERK2, and PaSERK5 was ubiquitous across the tissues we analyzed and did not display embryo-specific patterns ( Table I).…”

An Overview of Orchid Protocorm-Like Bodies: Mass Propagation, Biotechnology, Molecular Aspects, and Breeding

“…Ref. [52] characterized and analyzed the expression of 5 of these genes in Phalaenopsis and which were described by the authors as PhSERK. According to this study, the expression of these 5 genes was observed in various parts of plants (root, leaf, apical bud, and flower meristem) as well as during seed germination and PLB induction.…”

“…Although cytological features indicate that a PLB is a somatic embryo and studies have shown PhSERK gene expression during PLB induction [52], transcriptome studies developed by [29] analyzing gene expression in Phalaenopsis aphrodite concluded that PLBs are molecularly distinct from zygotic embryos. According to the authors, PLBs share different transcriptomic signatures from zygotic embryos, and early processes of PLB development show a distinct regeneration program, not following the embryogenesis program.…”