Embryonic development in Arabidopsis thaliana: from the zygote division to the shoot meristem

Abstract

Postembryonic organ formation of plants is fueled with cells from the stem cell niches in the shoot and root meristems. During the last two decades many players that regulate stem cell maintenance have been identified. With these factors in hand, the mechanisms establishing stem cell niches during embryo development can be addressed. Here we discuss current models of how the shoot meristem stem cell niche arises during Arabidopsis embryo pattern formation.

SHOOT MERISTEMLESS trafficking controls axillary meristem formation, meristem size and organ boundaries in Arabidopsis

“…At the globular stage, CUC1 and CUC2 are expressed in a narrow stripe separating the two developing cotyledon primordia (Aida et al ., ; Takada et al ., ), where they trigger STM expression (Long et al ., ; Aida et al ., ). CUC1 overexpression results in ectopic meristem initiation, further supporting the idea that CUC genes induce STM (Takada et al ., ; Bosca et al ., ). In contrast, during post‐embryonic development, STM promotes expression of CUC1/2/3 , and also represses CUC1/2 by indirectly activating miR164a, which targets CUC mRNAs (Kwon et al ., ; Bosca et al ., ; Spinelli et al ., ).…”

“…CUC1 overexpression results in ectopic meristem initiation, further supporting the idea that CUC genes induce STM (Takada et al ., ; Bosca et al ., ). In contrast, during post‐embryonic development, STM promotes expression of CUC1/2/3 , and also represses CUC1/2 by indirectly activating miR164a, which targets CUC mRNAs (Kwon et al ., ; Bosca et al ., ; Spinelli et al ., ). These studies show that STM and CUC genes control SAM and boundary formation and patterning by positive and negative feedback regulation of each other's expression.…”

Transcriptional changes during ovule development in two genotypes of litchi (Litchi chinensis Sonn.) with contrast in seed size

“…In developing ovules, zygotic division is a metabolically active process at which apical-basal body of the polarized zygote is established by asymmetric divisions. The Homeobox proteins, WRKY and receptor kinases are known to express at high level during zygotic division919293. The homologues of these genes were up-regulated in large-seeded genotype at 6 DAA as compared to 0 DAA ovules, in contrast to the small-seeded ovules, where these were down regulated.…”

The CLAVATA signaling pathway mediating stem cell fate in shoot meristems requires Ca2+ as a secondary cytosolic messenger

“…Studies of CLV1 function in signaling cascades have typically focused on genes controlling stem cell fate in the SAM. CLV1 receptor function has been shown to occur in cells of the SAM, and later, during vegetative-to-reproductive developmental transition, in the inflorescence and floral meristems (Bosc a et al, 2011;Durbak and Tax, 2011). However, recent work has suggested a role for CLV1 in the primary root meristem also (Stahl et al, 2013;Williams and De Smet, 2013;Araya et al, 2014).…”