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

Expression analysis of fertilization/early embryogenesis-associated genes in Phalaenopsis orchids

“… 1 PaMADS39 and PaMADS51 belong to the Mα-subclass of type I MADS-box genes and are closely related to Arabidopsis AGL23 and AGL62 1 . Similar to temporal expression patterns of AGL23 and AGL62, PaMADS39 and PaMADS51 are expressed in reproductive tissues when fertilization occurs and embryo development initiates.…”

“…Phylogenetic analysis puts PaMADS63 in the MIKC* subclass of type II MADS domain transcription factors 1 . The MIKC* type MADS domain proteins belong to a divergent class of type II MADS domain proteins and are expressed specifically in mature pollen of Arabidopsis 13 and rice, 11 and in gametophytic generation of moss Funaria hygrometrica 14 .…”

“…Based on our RNA-seq data set, expression of Phalaenopsis INDOLE-3-ACETIC ACID inducible 30 like ( PaIAA30L1 ) and EIN3-like 1 ( PaEIN3L1 ) genes is specifically enriched at 70–80 DAP when fertilization occurs and embryogenesis initiates (Table 1). 1 PaIAA30L1 encodes an auxin-induced AUX/IAA transcriptional repressor. PaEIN3L1 encodes an EIN3 domain transcriptional activator 28 .…”

“…The molecular mechanisms evolved to carry out this strategic reproductive program remain unclear. In the August issue of Plant Physiology 1 , we report comprehensive studies of comparative genome-wide gene expression in various reproductive tissues and the molecular events associated with developmental transitions unique to sexual reproduction of Phalaenopsis aphrodite . Transcriptional factors and signaling components whose expression is specifically enriched in interior ovary tissues when fertilization occurs and embryos start to develop have been identified.…”

“…These data provide cellular and molecular evidence that fertilization occurs at approximately 70 d after pollination (DAP) in P. aphrodite . In addition to the egg-specific marker, several transcription factors, methyltransferases, hormone signaling components, and cell cycle regulators 6 have also been shown to display fertilization-associated expression patterns 1 . Isolation of theses genes provides a novel opportunity to study the unique sexual reproduction of Phalaenopsis orchids.…”