Rice最新文献

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.

Grain weight and panicle architecture are pivotal determinants of rice yield, yet the regulatory mechanisms coordinating these traits remain elusive. Here, we functionally characterized a phytochrome-interacting factor, OsPIL11, serving as a negative regulator of grain weight and grain number per panicle. Knocking out OsPIL11 resulted in increased grain weight and grain number per panicle. OsPIL11 regulates grain weight by affecting cell expansion and division in the spikelet hulls, and controls grain number per panicle by regulating the number of primary branches. We further identified MicroRNA530, and cytokinin oxidase/dehydrogenase 2 as the target genes of OsPIL11 to regulate grain size and grain number in rice. Analysis of genetic variations suggested that there are two main haplotypes (Hap1 and Hap2) of OsPIL11. Hap1 confers the increased grain width and grain weight compared to Hap2, implying Hap1 as a superior haplotype for yield improvement. These findings provide novel insights into the molecular mechanisms underlying the regulation of rice yield, offering valuable genetic resources for the development of high-yield rice varieties through molecular breeding approaches.

Magnesium (Mg) and calcium (Ca) are the most abundant divalent cations in plants. Cause their antagonistic interaction in plant cell, maintaining Ca-Mg balance is critical for optimal plant growth and development. However, the molecular mechanisms underlying the regulation of Ca-Mg balance remain poorly understood. In this study, we found that the expression of OsCAX1a was highly induced under high Ca:Mg ratio conditions in rice. Heterologous expression of OsCAX1a in yeast demonstrated that it enhances cytosolic Mg efficiency by mediating Ca efflux. Genetic knockout or overexpression of OsCAX1a in rice altered the Ca:Mg ratio and impaired growth performance. Collectively, our results indicate that OsCAX1a-mediated Ca efflux plays an important role in Mg homeostasis, providing a new insight for Ca-Mg balance in plant.