Rice Science最新文献

Anthropogenic methane emissions are a leading cause of the increase in global average temperatures, often referred to as global warming. Flooded soils play a significant role in methane production, where the anaerobic conditions promote the production of methane by methanogenic microorganisms. Rice fields contribute a considerable portion of agricultural methane emissions, as rice plants provide both factors that enhance and limit methane production. Rice plants harbor both methane- producing and methane-oxidizing microorganisms. Exudates from rice roots provide source for methane production, while oxygen delivered from the root aerenchyma enhances methane oxidation. Studies have shown that the diversity of these microorganisms depends on rice cultivars with some genes characterized as harboring specific groups of microorganisms related to methane emissions. However, there is still a need for research to determine the balance between methane production and oxidation, as rice plants possess the ability to regulate net methane production. Various agronomical practices, such as fertilizer and water management, have been employed to mitigate methane emissions. Nevertheless, studies correlating agronomic and chemical management of methane with productivity are limited. Moreover, evidences for breeding low-methane-emitting rice varieties are scattered largely due to the absence of coordinated breeding programs. Research has indicated that phenotypic characteristics, such as root biomass, shoot architecture, and aerenchyma, are highly correlated with methane emissions. This review discusses available studies that involve the correlation between plant characteristics and methane emissions. It emphasizes the necessity and importance of breeding low-methane-emitting rice varieties in addition to existing agronomic, biological, and chemical practices. The review also delves into the ideal phenotypic and physiological characteristics of low-methane-emitting rice and potential breeding techniques, drawing from studies conducted with diverse varieties, mutants, and transgenic plants.

The aroma of fragrant rice is one of the grain quality attributes that significantly influence consumer preferences and prices in world markets. The volatile compound 2-acetyl-1-pyrroline (2AP) is recognized as a key component of the aroma in fragrant rice. The variation in grain 2AP content among various fragrant rice varieties is associated with the expression of the badh2 gene, with 19 alleles having been identified so far. The grain 2AP content is strongly influenced by environmental and management factors during cultivation as well as post-harvest conditions. This review pinpointed the major abiotic and biotic factors that control grain 2AP content. Abiotic factors refer to water, temperature, light quality, fertilizer application (both macro- and micro-nutrients), and soil properties, including salinity, while biotic factors include microorganisms that produce aromatic compounds, thus influencing the grain aroma in fragrant rice. Post-harvest management, including storage and drying conditions, can significantly impact the grain 2AP content, and proper post-harvest conditions can intensify the grain aroma. This review suggests that there are rice varieties that can serve as potential sources of genetic material for breeding rice varieties with high grain aroma content. It offers an overview of recent research on the major factors affecting the aroma content in fragrant rice. This knowledge will facilitate further research on the production of high-quality rice to meet the demands of farmers and consumers.

Pentatricopeptide repeat (PPR) proteins represent one of the largest protein families in plants and typically localize to organelles like mitochondria and chloroplasts. By contrast, CYTOPLASM- LOCALIZED PPR1 (OsCPPR1) is a cytoplasm-localized PPR protein that can degrade OsGOLDEN- LIKE1 (OsGLK1) mRNA in the tapetum of rice anther. However, the mechanism, by which OsCPPR1 recognizes and binds to OsGLK1 transcripts, remains unknown. Through protein structure prediction and macromolecular docking experiments, we observed that distinct PPR motif structures of OsCPPR1 exhibited varying binding efficiencies to OsGLK1 RNA. Moreover, RNA-electrophoretic mobility shift assay experiment demonstrated that the recombinant OsCPPR1 can directly recognize and bind to OsGLK1 mRNA in vitro. This further confirmed that the mutations in the conserved amino acids in each PPR motif resulted in loss of activity, while truncation of OsCPPR1 decreased its binding efficiency. These findings collectively suggest that it may require some co-factors to assist in cleavage, a facet that warrants further exploration in subsequent studies.