Rice最新文献

The intersubspecific rice hybrid Xieyou9308 exhibits striking hybrid vigor and serves as a valuable resource for dissecting the genetic basis of yield heterosis in indica-japonica crosses. However, the molecular mechanisms underlying this hybrid vigor remain poorly understood. Leveraging a set of recombinant inbred lines (RILs) and an immortalized F2 (IMF₂) population derived from Xieyou9308, 1,300,425 genomic variants were identified, which were consolidated into 3818 BIN markers. Genomic regions inherited from Zhonghui9308 were positively associated with traits including plant height, heading date, panicle length, and grain number per panicle. In contrast, regions derived from XieqingzaoB, particularly those located on chromosome 3, positively associated with grain length and 1000-grain weight. In the RIL population, 43 additive QTLs and 3 pairs of epistatic QTLs were identified for 10 agronomic traits, with the majority mapped to chromosomes 3 and 10, which harbor candidate genes including Ehd1, GS3, and OsTB1. In the IMF₂ population, 118 significant QTLs exhibiting partial dominance and 11 epistatic interactions were identified, underscoring the contributions of both partial dominance and epistasis to trait expression. Transcriptomic analysis further corroborated these findings, showing that alleles predominantly from Zhonghui9308 contributed to a prolonged growth duration, while those from XieqingzaoB shortened the growth duration. Collectively, these findings indicate that the hybrid vigor exhibited in Xieyou9308 is attributable to the synergistic effects of superior parental alleles and their epistatic interactions. These insights offer a valuable foundation for molecular breeding strategies aimed at improving yield in indica-japonica hybrid rice.

Soil salinization seriously impacts the growth and development, yield, and grain quality of crops. Elucidating the molecular underlying of salt tolerance is crucial for advancing stress-resistant molecular breeding research in crops. Here, we identified a salt stress-responsive gene, SQUAMOSA-promoter binding protein like 10 (OsSPL10), and characterized its molecular function in conferring salt tolerance to rice. Firstly, we generated and characterized three distinct types of spl10 mutants using CRISPR/Cas9 mutagenesis. In spl10 mutant, the leaf withered rate was lower than that in wild type (WT), the plant height and fresh weight per plant of spl10 were higher than WT under salt stress, indicating that spl10 exhibits tolerance to salt stress. Based on biochemical and physiological assays, the OsSPL10/14 complex was identified as a key regulator of salt stress response in rice by modulating the homeostasis of reactive oxygen species (ROS). Besides, the RNA-Seq assay confirmed that OsSPL10 may be involved in plant hormone signal transduction and phenylpropanoid biosynthesis pathways under salt stress, providing valuable insights for exploring the downstream target genes of OsSPL10. These findings offer novel insights into the molecular mechanisms underlying salt tolerance mediated by the SPL transcription factor in plants.

Soil salinization is becoming a huge threat to reducing productivity of rice (Oryza sativa L.) around the world. Previous studies have found that some Domain of unknown function (DUF) proteins play an essential role in the growth and development of plants. The DUF936 family is reported to respond to abiotic stresses, but the specific molecular mechanisms of its members remain elusive. In this study, OsSSID6 (Salt-Stress Induced DUF936 protein) is found at the cell membrane and the protein's expression could be affected by several abiotic stresses. The CRISPR/Cas9 knockout lines increased salt tolerance in rice, whereas the overexpression lines showed more sensitivity. And meanwhile the similar changes of ROS-scavenging capacity were observed both in knockout and overexpression lines. Transcriptome analysis identified that the expression of genes linked to multiple metabolic pathways, including phenylpropanoid and flavonoid biosynthesis, and stress response, was significantly up-regulated in KO lines. Our findings reveal that OsSSID6 gene modulates rice salt stress tolerance by orchestrating a network of metabolic pathways, including those involved in the reactive oxygen species (ROS) scavenging system, phenylpropanoid and flavonoid biosynthesis and stress response-related mechanism. sThese results provide important information for engineering salt-tolerant crops.

Studying the salt tolerance mechanisms of rice under a single substrate has certain limitations. The salt tolerance strategies of rice may differ under different substrate conditions. This study established three substrate types by adjusting the proportions of laterite, peat moss, and river sand: S1 (high sand; low nutrient), S2 (medium sand; medium nutrient), and S3 (low sand; high nutrient). Compared with the respective fresh water control, the magnitude of dry weight reduction in each substrate gradually decreased (S1-S3), indicating that the salt stress was effectively alleviated. KEGG enrichment analysis of differentially expressed genes (DEGs) showed that Xiangliangyou900 may be more dependent on the remodeling of carbon metabolism pathway (compared to nitrogen metabolism) in S1, but the nitrogen metabolism pathway were more significant in S3. In S3, differential metabolites were significantly enriched in carbon and nitrogen metabolism pathways, but no such enrichment was found in S1, indicating that the S3 substrate, with its high nutrient and low river sand content, is more likely to trigger carbon and nitrogen metabolism remodeling. Under salt stress, the methylation level of C bases in the CHH type increased in S1 and decreased in S3. The methylation level of CHH-type C bases in the whole genome was more strongly correlated with the physicochemical parameters of the substrate (compared to CG and CHG types).This study speculated that rice may optimize its ability to adapt to salt stress by specifically regulating the methylation of CHH-type C bases to mediate gene expression. The results of this study help enrich the theoretical system of the rice salt stress response mechanism.

Brassinosteroids (BRs) play important roles in regulating nutrient uptake, and phosphorus (P) deficiency severely limits rice productivity. However, whether and how BRs mediate P use efficiency (PUE), particularly via root-rhizosphere processes, remains unclear. Over three years, we ran two pot experiments in a low-P soil (Olsen-P 6.8 mg kg⁻¹). Experiment 1 (Genotype × P): YG2 (strong low-P tolerant variety) and ZD88 (weak low-P tolerant variety) were grown under no P (0P) and normal P (NP) conditions. Experiment 2 (Chemical application× P): plant roots were irrigated with 2,4-epibrassinolide (2,4-EBL) or a BRs biosynthesis inhibitor under both 0P and NP rates, with distilled water as the control. Results showed that, relative to NP, 0P significantly decreased root BR (2,4-epibrassinolide and 2,8-homobrassinolide) content in both genotypes, with a smaller reduction in YG2 than in ZD88 under 0P. YG2 outperformed ZD88 in grain yield and PUE at both P rates, especially at 0P, mainly due to the enhancement of early-stage (before panicle initiation) P accumulation driven by its elevated BR content. Under 0P, YG2 also exhibited superior root morph-physiological traits, viz. root length, root activity, malate secretion, along with higher pyrroloquinoline quinone biosynthesis protein C (pqqC) gene copies and greater resin-P content in the rhizosphere. At 0P, applying 2,4-EBL increased root BR content, activated BR-signaling gene expression, improved root and rhizosphere traits, and enhanced early-stage P accumulation, whereas applying BRs biosynthesis inhibitor had opposite effects. Applying 2,4-EBL additionally favored recruitment of the phosphate-solubilizing bacterium Massilia. Correlation and structural equation model analyses supported a pathway whereby elevated BR content activated BR signaling and downstream cascades that strengthened root performance and enriched Massilia, thereby increasing absorptive capacity and rhizosphere P supply. Overall, BRs mediate grain yield and PUE by optimizing root-rhizosphere cooperation under P-deficiency conditions.

Rice serves as the staple food for over half of the world's population, yet its propensity to accumulate cadmium (Cd), a toxic heavy metal and potential human carcinogen, poses significant food safety concerns. OsNRAMP5, the primary transporter responsible for Cd and manganese (Mn) uptake in rice, has emerged as a key target for developing low-Cd rice varieties through breeding programs. However, the broader physiological roles of OsNRAMP5 beyond metal transport remain poorly understood. Here, we demonstrate that OsNRAMP5 mutations, while effectively reducing Cd accumulation, significantly compromise rice blast resistance by disrupting Mn homeostasis. Our mechanistic analysis reveals that Mn deficiency in osnramp5 mutants leads to reduced activities of critical defense enzymes, including manganese-dependent superoxide dismutase (Mn-SOD) and phenylalanine ammonia-lyase (PAL), resulting in decreased accumulation of hydrogen peroxide (H₂O₂) and lignin, which are essential components of plant defense responses. Furthermore, pathogen-induced expression of pathogenesis-related (PR) genes is markedly suppressed in osnramp5 mutants, indicating impaired immune signaling pathways. Importantly, our study also demonstrated that utilizing rice variety carrying major blast-resistance genes as a background can effectively eliminate the reduced rice blast resistance caused by OsNRAMP5 mutation. This study reveals an important trade-off between cadmium safety and disease resistance in rice breeding and provides a promising approach for developing rice varieties that balance low Cd accumulation with maintained blast resistance, informing breeding strategies that reconcile food safety and agronomic performance.