Functional Characterization of Rice MPK6 and Maize ufo1 Genes During Gametophyte and Seed Development
- Chatterjee, Debamalya
- [University Park, Pennsylvania] : Pennsylvania State University, 2021.
- Physical Description:
- 1 electronic document
- Additional Creators:
- Foolad, Majid
- Restrictions on Access:
- Restricted (PSU Only).
- Cereals are the staple source of human nutrition that collectively provide nearly 50% of dietary calories and proteins for the global population. Improvement of agricultural practices as well as plant genetic resources is required to meet the increasing demand of the growing population while coping with the rapidly changing climate. To achieve the desirable production of cereals, conventional breeding and modern genetic engineering approaches must be closely tied to the understanding of seed development and the biological mechanisms to withstand stress during reproduction. Rice (Oryza sativa L.) and maize (Zea mays L.) are major cereal crops cultivated worldwide. Despite substantial progress in understanding reproductive tissue development in these crops, a complete picture of biological events and the cross-talk of molecular factors that underpin seed development are still enigmatic. Transcriptional regulators, peptide signals, hormones, and sugars play crucial roles during reproduction. However, recent studies have started to identify genes and pathways that facilitate cross-talk between these well-studied factors. This study is focused on the functional characterization of rice Mitogen-Activated Protein Kinase 6 (OsMPK6) and maize unstable factor for orange1 (Zmufo1) genes to explore their roles in reproductive development. The MPKs are known for their canonical role in signal transduction in response to external and internal stimuli. This study contributes to newly emerging evidence of the functions of MPKs in reproductive development through deciphering the role of OsMPK6 in gametophyte formation. Loss of OsMPK6 function is lethal and heterozygous plants carrying one loss-of-function allele are partially sterile as shown in clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein9 nuclease (Cas9) mutants of OsMPK6. Our results showed that OsMPK6 is crucial for callose deposition in developing pollen and pistils. Loss of OsMPK6 function leads to a reduction in pollen viability and abnormal pollen wall formation. Additionally, our results indicate that the decrease in seed set in osmpk6 mutants might result from impaired embryo sac formation. Even when the seed set is normal, abnormal endosperm development can affect the germination, seedling survival, and quality of cereal grain. The maize spontaneous gain-of-function mutant Unstable factor for orange1-1 (Ufo1-1) produces seeds with reduced size, weight, and starch content. Zmufo1 is highly expressed in the basal endosperm during early seed development. Our study revealed abnormal differentiation of the basal endosperm transfer layer (BETL) in Zmufo1 mutants. The BETL is crucial for nutrient transport from the end of the phloem in the pedicel to the starchy endosperm (SE). We observed abnormal carbohydrate and hormone accumulation in the SE of Zmufo1 mutants. We found that altered expression of Zmufo1 affects hub genes crucial for carbohydrate accumulation and BETL differentiation. Transcriptome analysis showed downregulation of fundamental biological processes such as ribosome biogenesis and DNA replication. Oxidative DNA damage was elevated in the developing endosperm of Zmufo1 mutants. Zmufo1 encodes a nuclear protein that localizes to the nucleolus and interacts with different chromatin remodeling, DNA damage response, and ribosome biogenesis-related proteins. An unusual amino acid composition and a predicted intrinsically disordered region suggest that Zmufo1 protein might behave like disordered proteins to facilitate dynamic and diverse protein-protein interactions. Although the exact molecular function of Zmufo1 remains elusive, results from our study confirm the crucial role of this gene in seed development and stress response. In summary, this research demonstrates that OsMPK6 and Zmufo1 are crucial for the reproductive development of rice and maize, respectively. This study also provides evidence to fill gaps in our understanding of the intricate interplays between different molecular factors such as sugars, hormones, callose, and signal peptides during gametophyte and seed development.
- Dissertation Note:
- Ph.D. Pennsylvania State University 2021.
- Technical Details:
- The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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