Gene FhRWP Influences Various Developmental Traits in Citrus Reproduction

Greg Howard
17th June, 2024

Gene FhRWP Influences Various Developmental Traits in Citrus Reproduction

Image Source: Natural Science News, 2024

Key Findings

  • The study from Huazhong Agricultural University focused on the fast-growing Fortunella hindsii to explore chromatin accessibility during nucellar embryony initiation
  • Polyembryonic genotypes showed higher chromatin accessibility in the promoter region of the FhRWP gene, leading to increased expression of the gene
  • Reducing FhRWP expression decreased the number of nucellar embryos, while overexpressing it induced embryogenic callus formation, highlighting its role in plant development and embryogenesis
Citrus plants serve as a model for studying adventitious embryos, a form of asexual reproduction controlled by a single dominant gene, RWP. The gene, identified as the cause of nucellar embryogenesis, had its function partially understood until recent research from Huazhong Agricultural University provided deeper insights[1]. This study focused on the fast-growing Fortunella hindsii to explore chromatin accessibility during nucellar embryony initiation, revealing significant findings that tie together and expand on earlier research. The study discovered that polyembryonic (PO) genotypes exhibit elevated chromatin accessibility compared to monoembryonic (MO) ones. Specifically, one allele of the promoter region of FhRWP showed higher chromatin accessibility, correlating with increased expression of the allele carrying the causal structural variant. This suggests that the accessibility of chromatin in this region could be a key factor in the regulation of nucellar embryogenesis. The researchers conducted RNA interference (RNAi) and gene editing experiments on PO genotypes. They found that downregulating FhRWP expression reduced the number of nucellar embryos, while knocking out the gene led to abnormal axillary bud development. These results underscore the gene's role in embryogenesis and plant development. Overexpression experiments further demonstrated that FhRWP could induce embryogenic callus formation in MO stem segments, possibly through the regulation of the WUS-CLV signaling network and the ABA and cytokinin pathways. This finding marks the first demonstration of FhRWP's potential to reignite somatic cells' embryogenic fate. This study builds on earlier findings related to plant embryogenesis and totipotency. Previous research identified the BABY BOOM (BBM) gene as a major regulator of plant cell totipotency, capable of inducing asexual embryo formation when ectopically expressed[2]. Similar to FhRWP, BBM is involved in promoting cell proliferation and morphogenesis during embryogenesis[3]. The new study on FhRWP adds to this understanding by highlighting the gene's pleiotropic functions and its role in chromatin accessibility, which were not previously explored in the context of BBM. Moreover, the study ties into earlier research on somatic embryogenesis (SE) induced by growth regulators like 2,4-D and the plant hormone abscisic acid (ABA)[4]. The ABA pathway's involvement in SE is echoed in the new findings, where the ABA and cytokinin pathways are implicated in the regulation of FhRWP. This connection suggests a broader, conserved mechanism across different plant species and types of embryogenesis. The study also addresses some misconceptions in plant cell and tissue culture terminology. For instance, the idea that "somatic embryos have a single cell origin" has been challenged by recent insights into the complex regulatory networks involved in plant regeneration[5]. The new findings on FhRWP's role in nucellar embryogenesis and its regulatory network provide a more nuanced understanding of these processes, emphasizing the need for precise terminology in plant science. In summary, the research from Huazhong Agricultural University reveals the multifaceted role of the RWP gene in citrus, particularly in chromatin accessibility and embryogenesis. By demonstrating FhRWP's ability to induce embryogenic callus formation and its involvement in key signaling pathways, the study offers new tools for bioengineering applications in plant regeneration. These findings not only expand our understanding of plant embryogenesis but also integrate and build upon earlier research in the field.

FruitsGeneticsPlant Science

References

Main Study

1) Adventitious embryonic causal gene FhRWP regulates multiple developmental phenotypes in citrus reproduction.

Published 16th June, 2024

https://doi.org/10.1111/tpj.16870

Related Studies

2) BABY BOOM regulates early embryo and endosperm development.

https://doi.org/10.1073/pnas.2201761119

3) Ectopic expression of BABY BOOM triggers a conversion from vegetative to embryonic growth.

Journal: The Plant cell, Issue: Vol 14, Issue 8, Aug 2002

4) ABA signalling promotes cell totipotency in the shoot apex of germinating embryos.

https://doi.org/10.1093/jxb/erab306

5) Callus, Dedifferentiation, Totipotency, Somatic Embryogenesis: What These Terms Mean in the Era of Molecular Plant Biology?

https://doi.org/10.3389/fpls.2019.00536


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