Arabidopsis thaliana gonidialess A/Zuotin related factors (GlsA/ZRF) are essential for maintenance of meristem integrity

Abstract

Observation of a differential expression pattern, including strong expression in meristematic tissue of an Agave tequilana GlsA/ZRF ortholog suggested an important role for this gene during bulbil formation and developmental changes in this species. In order to better understand this role, the two GlsA/ZFR orthologs present in the genome of Arabidopsis thaliana were functionally characterized by analyzing expression patterns, double mutant phenotypes, promoter-GUS fusions and expression of hormone related or meristem marker genes. Patterns of expression for A. thaliana show that GlsA/ZFR genes are strongly expressed in SAMs and RAMs in mature plants and developing embryos and double mutants showed multiple changes in morphology related to both SAM and RAM tissues. Typical double mutants showed stunted growth of aerial and root tissue, formation of multiple ectopic meristems and effects on cotyledons, leaves and flowers. The KNOX genes STM and BP were overexpressed in double mutants whereas CLV3, WUSCHEL and AS1 were repressed and lack of AtGlsA expression was also associated with changes in localization of auxin and cytokinin. These results suggest that GlsA/ZFR is an essential component of the machinery that maintains the integrity of SAM and RAM tissue and underline the potential to identify new genes or gene functions based on observations in non-model plants.

Arabidopsis ZUOTIN RELATED FACTOR1 Proteins Are Required for Proper Embryonic and Post-Embryonic Root Development

“…AtZRF1a and AtZRF1b have similar and broad expression in almost all the young plant organs including root tips, shoot tips, developing leaves, inflorescences, floral buds, and embryos; their expression intensity is positively correlated with dividing activities of the organs (Guzman-Lopez et al, 2016). Consistently, loss of AtZRF1 function results in morphological defects in almost all the developmental phases related to dividing cells and meristematic tissues (Feng et al, 2016; Guzman-Lopez et al, 2016). Recently AtZRF1a/b have been reported to perform both PRC1-related and independent functions in regulating plant growth and development (Feng et al, 2016).…”

“…meristem, floral bud, and developing embryo. Loss-of-function of AtZRF1a/b causes pleiotropic abnormalities including delayed seed germination, plant dwarfism, formation of multiple ectopic meristems, and defects in flower development and gametophyte transmission as well as embryogenesis (Feng et al, 2016; Guzman-Lopez et al, 2016). The atzrf1a;atzrf1b mutant displays severely disrupted root developmental phenotype; yet, the underlying mechanism is far from clear.…”

A Novel Epigenetic Regulator ZRF1: Insight into Its Functions in Plants

“…Compared with wild-type seeds, the seeds of atglsa1-3 atglsa2-1 double mutants are shriveled, wrinkled, distorted, and small [23]. In atzrf1a-1 atzrf1b-1 and atzrf1a-2 atzrf1b-1 double mutants, plants are poorly fertile and seed abortion is observed.…”

“…Some seedlings (about 35%) exhibited a single cotyledon, asymmetrical cotyledons, and fleshy narrow cotyledonous phenotypes, which display some defects similar to Atbmi1aAtbmi1b and Atring1aAtring1b [22]. Through electron microscopy, severe defects in all stages of embryo development were observed, such as at the pre-globular, octant stage, unorganized division, and a lack of suspensor development; at the globular stage, failure of hypophysis development [23]. These phenomena suggest that ZRF1a/b plays a very important role in embryo development.…”

“…In most species, ZRF1 is evolutionarily conserved [9,22]. According to bioinformatics analysis, ZRF1 homologs are widely found in plants (e.g., A. thaliana, Lilium longiflorum, Alstroemeria aurea, Volvox carteri), and LlglsA (L. longiflorum gonidialess A) was identified as the first higher plant homolog of glsA/ZRF1 [22][23][24][25]. However, current studies of ZRF1 in plants are limited, and few indepth studies of its functions have been reported.…”