Location: Cereal Crops ResearchTitle: Genetic analysis of the barley variegation mutant, grandpa1.a
Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2021
Publication Date: 3/13/2021
Publication URL: https://handle.nal.usda.gov/10113/7309046
Citation: Yang, S., Overlander, M., Fiedler, J.D. 2021. Genetic analysis of the barley variegation mutant, grandpa1.a. BMC Plant Biology. 21(1):134. https://doi.org/10.1186/s12870-021-02915-9.
Interpretive Summary: Chloroplast development is a complicated process that is critical to crop biomass and economic yield, however, there is a gap in our understanding of chloroplast biogenesis. In the present study, we characterized and genetically analyzed the barley grandpa1 (gpa1) mutant with defects in chloroplast formation. Genetic mapping anchored the Gpa1 gene within a gene cluster functionally related to chloroplast development, and one promising candidate gene was selected for functional validation. Our results lay the foundation for plant biologist to clone Gpa1, which will further the understanding of the molecular mechanisms underlying chloroplast biogenesis.
Technical Abstract: Providing the photosynthesis factory for plants, chloroplast biogenesis is critical for crop biomass and economic yield. However, chloroplast development is a very complicated process coordinated by the cross-communication between the nucleus and plastids, and the underlying mechanism has not been fully revealed. To explore the regulation machinery for chloroplast biogenesis, we characterized and genetically analyzed one of the allelic variegation mutants in barley, grandpa1.a (gpa1.a) with defects in chloroplast formation. Besides the striped leaf phenotype, the gpa1 mutation also causes a systemic abnormality to barley growth and development. Genetic mapping anchored the Gpa1 gene onto 2H within a gene cluster functionally related to photosynthesis or chloroplast differentiation. One gene in the delimited region encodes a putative plastid terminal oxidase (PTOX) in thylakoid membranes, which is homologous to IMMUTANS (IM) of Arabidopsis. Loss of IM function in Arabidopsis leads to a variegated phenotype, and a large deletion was identified in the mutated allele of gpa1. It was speculated that this PTOX-encoding gene might be a promising candidate. Therefore, the present study provided a foundation for the cloning of Gpa1, which will further our understanding of molecular mechanisms underlying chloroplast biosynthesis, particularly in monocot plants.