Cell & Developmental Biology
Open Access

Prominent Genes Involved in Embryo Development of Arabidopsis thaliana

^*Correspondence: Dr. Kwong Isakov, Department of Clinical Pharmacology, University of Zimbabwe, Avondale, Harare, Zimbabwe, Email:

Author info »

Description

Plants use cells from stem cell niches in the shoot and root meristems to feed the creation of postembryonic organs. Many players that regulate stem cell maintenance have been uncovered throughout the previous two decades. The mechanisms generating stem cell niches during embryo development can be addressed with these components in hand. The single-cell zygote is formed by the union of male and female gametes during embryogenesis. Within the first five days of embryogenesis in Arabidopsis, the zygote divides asymmetrically, followed by precisely orientated cell divisions that form the primary tissue lineages of the adult plant. The shoot meristem stem cell niche key genes emerge during Arabidopsis embryo pattern creation was discussed here.

The Organizing Center (OC), a small group of L3 cells, expresses the plant-specific homeobox gene WUSCHEL (WUS). WUS is essential for the undifferentiated state of stem cells as well as the expression of CLAVATA3 (CLV3) in them. CLV3 acts as a negative feedback signal by binding to numerous leucine-richrepeat receptor-like kinases, including CLAVATA1 (CLV1), and inhibiting WUS transcription. This negative feedback loop between OC and stem cells provides a theoretical foundation for dynamically maintaining stem cell numbers. Similar to its maize homolog KNOTTED1, the ShootMeristemless (STM) gene is expressed throughout the meristem dome but not in incipient organ anlagen. STM keeps meristem cells alive by increasing cytokinin synthesis and suppressing the cytokinin antagonist gibberellic accumulation. STM also inhibits the production of Asymmetric leaves1 (AS1), a repressor of the meristem genes BP/KNAT1 and KNAT2, as well as the meristem genes BP/ KNAT1 and KNAT2. Leaf primordia are distinguished from the shoot meristem by the accumulation of auxin and gibberellins, as well as the expression of AS1/2, all of which promote differentiation.

The pollen, which contains the Short Suspensor (SSP) genes of mRNA, provides critical information for the zygote's asymmetric division. SSP encodes an interleukin-1 receptor-associated kinase/Pelle-like kinase and is located upstream of YODA, a MAPKK kinase. When SSP, YDA, or the downstream transcription factor Grounded (GRD) are lacking, zygote elongation fails, a more symmetric division occurs, and suspensor fate is misspecificated. Mutations in the WRKY2 gene cause the zygote to split more symmetrically. The nucleus is shifted to the top half of the zygote in the WRKY2 mutant, and there is no buildup of vacuoles in the lower half, indicating that WRKY2 is involved in this process. The nucleus is transferred to the top half of the cell in the WRKY2 mutant. The transfer of the nucleus to the top half of the zygote and the formation of vacuoles in the basal half do not occur in the WRKY2 mutant, indicating that WRKY2 is involved in zygote polar organisation. In contrast to wild type, where the basal daughter cell has prominent vacuoles, the two daughter cells in WRKY2 are not only identical in size but also have prominent vacuoles.

As early as the cardiac embryo stage, CLV1 and CLV3 mRNA were discovered in the shoot meristem primordium from the heart stage on, CLV1 and CLV3 mutants have a higher expression domain of WUS, indicating that the CLV signaling cascade is active. CLV3 expression is not seen in mature WUS embryos, indicating that WUS is necessary for CLV3 expression during embryogenesis. The commencement of CLV3 expression, the involvement of WUS therein, and the initiation of the WUS/CLV3 feedback regulation in the embryo will all be of interest to researchers. The embryo's symmetry is established bilaterally, and the middle is designated as a shoot meristem primordium. Auxin, Cup-shaped Cotyledon (CUC) genes, and the STM gene all play a role in establishing bilateral symmetry in the embryo and defining the canter as the shoot meristem primordium. CUC1 and CUC2 are expressed in a narrow stripe dividing the presumed cotyledonary primordial and the presumptive cotyledonary primordial at the globular embryo stage.

Conclusion

Over the last decade, quality and value involved in the development of the Arabidopsis embryo have been identified. Many of them were discovered using postembryonic mutant phenotypes, thus it's not unexpected that our understanding of embryo patterning is currently skewed toward postembryonic network initiation. It needs to be seen if there is an underlying collection of embryo-specific regulators that is not discovered in standard mutant screens. Insight could be gained through genetic screens in hypersensitive backgrounds, searches for aberrant expression patterns, or reverse genetics based on embryo cell-specific expression profiles. Once the players are identified, obtaining high resolution of their spatiotemporal patterns of expression and function becomes a priority.