Findings reveal that OsELP3/ELP4 regulates histone acetylation-mediated defense responses against M.oryzae, providing both theoretical foundations and genetic resources for developing blast-resistant rice cultivars.
Abstract
Rice blast, caused by Magnaporthe oryzae (M.oryzae), is one of the three most devastating rice diseases, significantly reducing both yield and grain quality. The Elongator complex, first characterized in Arabidopsis thaliana, regulates growth, development, and innate immunity by tightly associating with hyperphosphorylated RNA polymerase II. However, its immunological role in rice remains unexplored. Here, we demonstrate that Elongator plays an essential role in rice blast resistance. The OsELP3 subunit mutant exhibited susceptibility to M.oryzae, while its overexpression increased resistance. OsELP3 interacts with its homologous subunit OsELP4 in the nucleus, and that OsELP4 also positively regulates rice blast resistance. RNA-seq and histone acetylation analyses demonstrated that OsELP3/ELP4 enhances transcriptional activation of key rice blast resistance genes by modulating histone acetylation levels in both the jasmonic acid (JA) signaling pathway (OsAOS1, OsLOX6, OsPROPEP3) and lignin biosynthesis pathway (OsMYB30, OsMYB55, OsMYB110), thereby strengthening plant defense mechanisms against M. oryzae. These findings reveal that OsELP3/ELP4 regulates histone acetylation-mediated defense responses against M.oryzae, providing both theoretical foundations and genetic resources for developing blast-resistant rice cultivars.
Rice (Oryza sativa L.) is a major food crop worldwide. With the acceleration of global warming, drought is becoming one of the major limitations for rice productivity. In plants, MYB transcription factors (TF) play pivotal roles in mediating drought stress tolerance. The rice OsMYB61 encodes an R2R3-MYB protein. OsMYB61 is localized both in the nucleus and the stomatal guard cells in the Nicotiana benthamiana leaves. The expression of OsMYB61 is repressed by ABA and PEG treatments. OsMYB61-overexpressing rice lines exhibited decreased drought tolerance. qRT-PCR evidence showed that the transcription levels of OsDREB2A and OsNCED1/4 in transgenic rice plants were differentially altered by PEG treatment. The yeast one-hybrid (Y1H) assay and transient luciferase reporter experiments demonstrated that OsMYB61 may bind to the promoters OsNCED1/4 and OsDREB2A, and hence inhibits their expression. OsRFP1 is a RING-finger E3 ubiquitin ligase and promotes stomatal opening. Our evidence showed that OsMYB61 interacts with and ubiquitinates OsRFP1 directly, thereby promoting its degradation via the ubiquitin-26S proteasome pathway. Moreover, knockout of OsRFP1 via the CRISPR-Cas9 technique led to decreased drought and osmotic tolerance of osrfp1 mutants, implying that OsRFP1 positively regulates drought and osmotic stress response. Furthermore, co-expression of OsRFP1 and OsMYB61 attenuated the repressive effects of OsMYB61 on the transcription of OsNCED1/4 and OsDREB2A. Collectively, our findings unraveled the molecular mechanisms of the OsRFP1-OsMYB61 module in regulating rice drought tolerance, which provide potential targets for rice breeding with improved drought tolerance.
Drought stress severely restricts global rice production, making the improvement of drought tolerance a central goal in rice breeding. Here, we identify the rice FCS-like zinc finger protein 20 (OsFLZ20) as a previously unrecognized client of the 14-3-3 protein OsGF14f, a recently characterized and promising target for engineering drought-tolerant rice cultivars. OsFLZ20 transcription is rapidly and robustly induced by drought, and transgenic analyses show that it does not affect normal growth or yield but instead acts as a positive regulator of drought tolerance by increasing soluble sugar accumulation and alleviating oxidative damage. OsGF14f and OsFLZ20 co-regulate a broad suite of drought-responsive genes, with OsGF14f serving as a positive modulator of OsFLZ20-driven transcriptional reprogramming. Mechanistically, OsGF14f interacts with OsFLZ20 at Ser-64 and increases its protein abundance. In parallel, the OsGF14f-OsbZIP23 module enhances the transcriptional activation of OsFLZ20 under drought stress. Further genetic analyses reveal that full OsFLZ20 function in drought tolerance requires a functional OsGF14f, whereas loss of OsFLZ20 compromises the drought tolerance conferred by OsGF14f, indicating mutual interdependence of these two regulators within the drought response network. Collectively, these findings establish the OsGF14f-OsbZIP23-OsFLZ20 module as a previously unrecognized determinant of rice drought tolerance and provide valuable genetic resources and molecular insights for crop improvement under water-limited conditions.
Qing Liu, Fu-Jun Wang, Ke Ding et al.· Plant Communications· 0 citations
SUMMARY The ubiquitin‐conjugating enzymes (E2) play critical roles in plant stress responses and development, but their functions in ABA‐mediated seed germination in rice remain largely unknown. We identified two homologous E2 enzymes, OsUBC11 and OsUBC12, which are highly expressed in rice seeds and induced by multiple abiotic stresses including salt, osmotic stress, and ABA treatment. We demonstrated that OsUBC11 and OsUBC12 positively regulate rice seed germination, especially under NaCl and ABA treatment, as the double mutants exhibited delayed germination and hypersensitivity to ABA and salt, while overexpression lines showed accelerated germination and reduced sensitivity. OsUBC11 and OsUBC12 negatively regulate the expression of ABA‐responsive genes, including OsABI3, OsABI5, OsRAB21, and OsLEA3. Protein interaction assays demonstrated that OsUBC11/12 directly interact with OsABI3, a key transcription factor in ABA signaling. OsUBC11/12 possess ubiquitin‐conjugating activity and promote the ubiquitination and subsequent degradation of OsABI3, thereby reducing OsABI3 protein stability. Together, our findings establish that OsUBC11 and OsUBC12 positively regulate seed germination under salt stress by ubiquitinating and destabilizing OsABI3, thus attenuating ABA signaling.
Tian-Ci Xie, Tao Qing, Chuang Yang et al.· The Plant Journal· 0 citations
ABSTRACT Soil salinity severely impairs rice yield and quality, yet the molecular mechanisms of its salt tolerance remain unclear. In this study, we first discovered OsbZIP79, a novel basic leucine zipper (bZIP)‐type transcription factor, as a positive regulator of salt tolerance in rice. We uncovered that OsbZIP79 positively regulates the expression of OsHAK26 (encoding a potassium transporter) and OsMPG1 (encoding a mannose‐1‐phosphate guanylyltransferase) to confer salt tolerance in rice. In vivo and in vitro evidence demonstrate that OsbZIP79 physically interacts with Ideal Plant Architecture1 (IPA1), a known negative regulator of salt stress responses. IPA1 represses the expression of OsbZIP79 and competes with the OsbZIP79 C‐terminus for binding to the promoters of its target genes. Haplotype analysis of 4726 rice accessions identified Hap3 of OsbZIP79 as a favorable allele that confers significantly enhanced salinity tolerance compared to Hap1 and Hap2. These findings reveal a novel salt tolerance regulatory network governed by the OsbZIP79‐IPA1 module. This work provides insights to facilitate the improvement of salt tolerance in rice through advanced breeding.
Hui Wang, Bo Liu, Can Hu et al.· Advancement of science· 0 citations
Plant nitrogen uptake and utilization are governed by a complex network involving nitrate transporters and signal-responsive genes. Here, we show that the high mobility group box 1 protein OsHMGB1 directly binds to the OsNRT2.2 promoter and functions as a transcriptional repressor, negatively regulating its expression. Knockout of OsHMGB1 upregulates OsNRT2.2 expression, leading to increased nitrate accumulation and enhanced tolerance to low-nitrogen (LN) conditions in rice seedlings. Furthermore, OsHMGB1 expression is significantly reduced in OsCBL1-knockdown (OsCBL1-KD) plants, suggesting its dependence on OsCBL1-mediated signaling. OsHMGB1 acts additively with OsCCA1, a known repressor that binds the OsNRT2.2 promoter, to negatively regulate OsNRT2.2 expression. Notably, sequence variation in the OsHMGB1 promoter between indica and japonica rice varieties correlates with lower expression levels in indica varieties, which are associated with higher nitrogen use efficiency (NUE)-related agronomic traits, specifically, greater grain yield and increased number of effective panicles, in indica varieties compared with japonica. Together, these findings identify OsHMGB1 as a key repressor of OsNRT2.2, associated with OsCBL1-dependent nitrate signaling and act additively with OsCCA1 to enhance LN tolerance, suggesting that OsHMGB1 expression levels correlate with NUE-related traits under LN conditions. This work elucidates a link between calcium signaling and nitrate response in rice.
Jiawei Niu, Yutan Guo, Jia-Qi Cheng et al.· International Journal of Bio...· 0 citations
Heat stress severely impairs plant growth and limits crop productivity. GSK3-like family proteins regulate diverse cellular processes, including plant responses to abiotic and biotic stresses. Nevertheless, their specific functions in heat stress responses remain poorly characterized. Here, we demonstrate that the expression of OsSK13 and the protein abundance of OsSK12/13 increase under heat stress in rice. Mutation in both OsSK12/13 compromises thermotolerance at both vegetative and reproductive stages, whereas overexpression of OsSK13 enhances seedling thermotolerance. We further identify that OsSK12/13 physically interact with and phosphorylate the APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF) transcription factor OsERF60, and phosphorylation by OsSK12/13 enhances the stability of OsERF60. Consistent with its role in this regulatory module, OsERF60 loss-of-function mutants exhibit enhanced thermosensitivity at vegetative and reproductive stages. Expression profiling reveals that induction of heat stress-responsive genes, including OsHsfA2c, is reduced in both the OsSK12/13 double mutant and the OsERF60 mutant. OsERF60 directly binds to the OsHsfA2c promoter and activates its expression. Collectively, our findings uncover the OsSK12/13-OsERF60-OsHsfA2c regulatory module as a key component of the heat stress response in rice and provide mechanistic insights into thermotolerance in plants.
Juan Gao, Zi-Wei Yao, Zhiping Deng et al.· Journal of Integrative Plant...· 0 citations
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