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Semi-dwarfing improves the lodging resistance and yield of rice, and the vast majority of modern rice varieties harbor the sd1 allele to decrease plant height, resulting in reduced genetic diversity and negative agronomic traits. Thus, exploring alternative sources of dwarfism is imperative for rice breeding. Here, we identified a novel RGA1 allele, d1-w, from a local indica variety Xiaolixiang (XLX) using a map-based cloning approach. Compared with other rice varieties, RGA1 in XLX contained a unique single nucleotide polymorphism that resulted in an additional transcript and reduced functional RGA1 transcript level. The RGA1 from Nipponbare was introduced into XLX to estimate the value of d1-w in rice breeding. Compared with transgenic XLX plants (XLXD1), XLX exhibited reduced plant height, increased stem strength, lower reactive oxygen species accumulation, delayed senescence, stronger photosynthesis, higher grain yield and quality (including external, milling and nutritional qualities), and enhanced resistance to drought and Rhizoctonia solani. Therefore, we proposed that the d1-w allele has potential as an excellent dwarfism resource for rice breeding.

BACKGROUND: Rice sheath blight caused by Rhizoctonia solani is a severe threat to the yield and quality of rice. Due to the unscientific abuse of common fungicides causing resistance and environmental issues, the development of new fungicides is necessary. In this study, we used citral as the lead compound, designed and synthesized a series of novel citral amide derivatives, and evaluated their antifungal activity and mode of action against R. solani. RESULT: Bioassay results indicated that the antifungal activities of most citral amide derivatives against R. solani were significantly improved compared to citral, with EC50 values ranging from 9.50–27.12 mg L−1. Among them, compound d21 containing the N‐(pyridin‐4‐yl)carboxamide group exhibited in vitro and in vivo fungicidal activities, with curative effects at 500 mg L−1 as effectively as the commercial fungicide validamycin·bacillus. Furthermore, d21 prolonged the lag phase of the growth curve of R. solani, reduced the amount of growth, and inhibited sclerotium germination and formation. Mechanistically, d21 deformed the mycelia, increased cell membrane permeability, and inhibited the activities of antioxidant and tricarboxylic acid cycle (TCA)‐related enzymes. Metabolome analysis showed the abundance of some energy‐related metabolites within R. solani increased, and simultaneously the antifungal substances secreted by itself reduced. Transcriptome analysis showed that most genes encoding ATP‐binding cassette (ABC) transporters and peroxisomes upregulated after the treatment of d21 and cell membrane destruction. CONCLUSION: This study indicates that novel citral amide derivatives possess antifungal activity against R. solani and are expected to develop an alternative option for chemical control of rice sheath blight. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Compensatory effects are common biological phenomena in nature. In this study, we investigated the changes in root nitrogen uptake, root morphological and physiological responses, and changes in the rhizosphere soil microbial communities of indica and japonica rice during a nitrogen deficiency‐sensitive period and an effective compensation period with double the nitrogen supply. We conducted a bucket experiment using Suxiu 867 (a japonica rice variety) and Yangxian You 918 (an indica rice variety). Treatments included CK (constant distribution of nitrogen fertilizer at each growth stage, represented by CK867 and CK918) and NDC (nitrogen deficiency in the tillering stage, double nitrogen application in the ear differentiation stage to compensate, represented by NDC867 and NDC918) variations. Both varieties presented the highest δ15N and 15N abundances and Ndff (refers to the proportion of nitrogen in a plant's body that comes directly from the fertilizer applied.) in rice under the NDC treatment. Metagenomic sequencing of rhizospheric soil showed that the dominant bacterial groups at the phylum level among each treatment were Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria, Gemmatimonadetes, and Nitrospirae. The rhizosphere of indica rice was more enriched with the microbial communities involved in nitrogen metabolism, which contributed to higher nitrogen utilization efficiency. A correlation‐based network was constructed and provides insights into the formation of nitrogen deficiency compensation effects and contributes to the enhancement of nitrogen uptake and utilization efficiency in rice production. [ABSTRACT FROM AUTHOR]

P1B-type heavy metal ATPases (HMAs) are transmembrane metal-transporting proteins that play a key role in metal homeostasis. We here reported the characterization of rice OsHMA6, a member of the P1B-type ATPase family. Phylogenetic tree analysis showed that OsHMA6 belonged to the Cu/Ag subgroup of the HMA family and had a close evolutionary relationship with OsHMA9. Amino acid sequence alignment showed 82.78% consistency between OsHMA6 and OsHMA9. OsHMA6 expressed in all organs at different growth stages, including spikelet, and abundant in leaf blades, however, OsHMA9 most strongly expressed in roots, but very low in spikelet. Excessive Cu2+ can up-regulate the expression of OsHMA6 and OsHMA9 in rice seedlings. The heterologous expression in yeast showed that OsHMA6 can significantly rescue the growth of yeast strain CM52 when supplied with 3 or 6 mmol/L Cu2+. Compared with the empty vector pYES2, the Cu concentration in OsHMA6-pYES2 decreased by 23.4% and 30.3% under 3 or 6 mmol/L Cu2+, respectively. Subcellular localization revealed that OsHMA6 was located in the plasma membrane. These results suggested that OsHMA6, similar to OsHMA9, is likely a copper efflux protein located in the plasma membrane. Keywords: OsHMA6, P1B-type ATPase, copper, cadmium, efflux, rice, subcellular localization

To better understand RNA-binding proteins in rice, a comprehensive investigation was conducted on the RRM1 gene family of rice. It encompassed genome-wide identification and exploration of its role in rice blast resistance. The physicochemical properties of the rice OsRRM1 gene family were analyzed. There genes were also analyzed for their conserved domains, motifs, location information, gene structure, phylogenetic trees, collinearity, and cis-acting elements. Furthermore, alterations in the expression patterns of selected OsRRM1 genes were assessed using quantitative real-time PCR (qRT-PCR). A total of 212 members of the OsRRM1 gene family were identified, which were dispersed across 12 chromosomes. These genes all exhibit multiple exons and introns, all of which encompass the conserved RRM1 domain and share analogous motifs. This observation suggests a high degree of conservation within the encoded sequence domain of these genes. Phylogenetic analysis revealed the existence of five subfamilies within the OsRRM1 gene family. Furthermore, investigation of the promoter region identified cis-regulatory elements that are involved in nucleic acid binding and interaction with multiple transcription factors. By employing GO and KEGG analyses, four RRM1 genes were tentatively identified as crucial contributors to plant immunity, while the RRM1 gene family was also found to have a significant involvement in the complex of alternative splicing. The qRT-PCR results revealed distinct temporal changes in the expression patterns of OsRRM1 genes following rice blast infection. Additionally, gene expression analysis indicates that the majority of OsRRM1 genes exhibited constitutive expressions. These findings enrich our understanding of the OsRRM1 gene family. They also provide a foundation for further research on immune mechanisms rice and the management of rice blast. [ABSTRACT FROM AUTHOR]