The Plant Journal最新文献

Double flower, which is one of the most important characteristics of ornamental plants, is closely related to their ornamental and commercial value. The double-flower trait in rose was mainly due to the increase in petal number caused by stamen petalization. However, the mechanism regulating petal number is not clear. In this study, the Rosa chinensis “Zhaiye Tengben Yuejihua” × R. chinensis “Old Blush” population was used for QTL detection and NGS-based BSA analysis to identify candidate genes related to petal number. It was found that RcAP2L and RcAS1 were highly expressed in double-flower rose, while RcAGL80 was highly expressed in single-flower rose. Silencing RcAP2L and RcAS1 reduced the petal number by inhibiting homeotic conversion of stamens to petals, separately. However, silencing RcAGL80 increased the petal number by promoting homeotic conversion of stamens to petals. The results of Y2H and BiFC assays showed that RcAP2L interacted with RcAS1. The dual-luciferase assay showed that RcAP2L was bound to the promoter of RcAGL80 and suppressed RcAGL80 transcription. In total, we found a new function of AS1 in specifying flower organ identity, and a new pathway for regulating the number of petals by RcAS1, RcAGL80, and RcAP2L, which provides new information for elucidating the mechanism of the formation of double flower in rose.

Nitrate is a key nutrient and one of the most important nitrogen sources for land plants. Besides its nutritional role, nitrate is a signal molecule that regulates plant gene expression, metabolism, physiology, growth, and development. In cotyledons and true leaves, nitrate promotes growth by inducing cell expansion. Plant cell expansion requires changes in the cell wall. However, there is scant information on the influence of nitrate on cell wall metabolism and properties during cell expansion and growth. Here, we demonstrate that nitrate availability modulates pectin metabolism, a major polysaccharide of the primary cell wall. Using colorimetric assays, immunohistochemistry, and confocal microscopy, we show that nitrate enhances methylesterified pectin during cotyledon cell expansion. This is achieved by increasing galacturonic acid (GalA) deposition as homogalacturonan (HG) and by decreasing global PME activity. We further show that this regulation is dependent on nitrate signaling pathway components, including NRT1.1 and NLP7. Pectin methylesterification state impacts the mechanical properties of the cell wall. We characterized cell wall elasticity changes during nitrate-induced expansion using atomic force microscopy (AFM) and automatic confocal microextensometry (ACME). We found that nitrate induces cell wall softening at both cellular and whole-tissue levels during this expansion process. Our results indicate pectin metabolism plays an important role in nitrate-induced cell expansion and cotyledon growth in Arabidopsis. We provide insights into the interplay between nitrate signaling, cell wall metabolism, and biomechanical properties for cell expansion. Our results contribute to our understanding of how plants sense and respond to environmental cues for growth.

The Qinghai-Tibet Plateau (QTP) harbors diverse alpine flora, including the ecologically significant shrubs Dasiphora fruticosa and D. glabra, for which taxonomic uncertainties remain and adaptive mechanisms are still poorly understood. Based on high-quality genome assembly, population resequencing, and multi-omics integration, we elucidated their evolutionary divergence and flower color genetics. Chromosome-level haplotype-resolved genomes were assembled: autotetraploid D. fruticosa (929.99 Mb) and diploid D. glabra (450.89 Mb). Phylogenetic analysis showed that the tetraploid D. fruticosa and D. glabra in this study clustered together, while the diploid D. fruticosa sequenced by previous research formed a distinct lineage clustered outside. Consistently, population structure analysis of 55 samples revealed three major clades, with D. fruticosa further subdivided into two divergent branches. Additionally, hybridization events detected by Admixture, coupled with ploidy complexity identified via flow cytometry highlight the intricate genetic relationships within this genus. Adaptive gene families expanded in antioxidant (flavonoid synthesis) and secondary metabolism pathways, adapting to ultraviolet radiation and cold stress. Natural selection analysis identified 193 candidate genes (e.g., TFB5 in the DNA repair pathway), predominantly localized to chromosome 5, which are potential candidates for high-altitude adaptation. Transcriptome and metabolome analyses showed D. fruticosa's yellow petals derive from flavonol (quercetin) accumulation, while D. glabra's white petals result from proanthocyanidin biosynthesis via high LAR/ANR expression. This study provides insights into the taxonomic revision and adaptive genetic divergence of alpine plants, and offers a foundation for horticultural improvement of Dasiphora.

α-Linolenic acid (ALA) is an omega-3 polyunsaturated fatty acid (FA) that is essential for human health and is obtained mainly from plant-sourced foods. The tree peony (Paeonia rockii) is a woody oilseed plant with high nutritional value, as its seed oil is rich in ALA. Previously, we found that tree peony phospholipid diacylglycerol acyltransferase 2 (PrPDAT2) plays an important role in seed oil ALA accumulation. However, the transcriptional mechanism by which PrPDAT2 promotes ALA accumulation in seed oils remains incompletely understood. Here, we identify a novel tree peony trihelix transcription factor (TF), PrASR3, that acts as a repressor of ALA accumulation in the seed by directly inhibiting PrPDAT2 transcription. Furthermore, our findings also show that the overexpression of PrASR3 in Nicotiana benthamiana leaves and Arabidopsis thaliana seeds alters FA composition. Silencing of PrASR3 in P. rockii seeds resulted in enhanced PrPDAT2 expression and ALA accumulation. In addition, we further demonstrated that the TEOSINTE BRANCHED 1/CYCLOIDEA/PCF (TCP) TF PrTCP14 interacts with PrASR3 to attenuate the inhibitory effect of PrASR3 on seed ALA accumulation. Overall, these findings enrich insight into the molecular regulatory mechanism of ALA accumulation in plants and provide a novel target for oil quality improvement in oilseed plants.

N⁶-methyladenosine (m6A) is the most abundant mRNA modification in organisms. To investigate the dynamics of m6A under salt stress in poplar, 84K poplar (Populus alba × Populus tremula var. glandulosa) and Xiaohei (XH) poplar (Populus simonii × Populus nigra) were subjected to salt treatment followed by MeRIP-seq analysis. The results showed that genes such as ATWRKY40, ATPK19, FDH, and GRX480 exhibited similar methylation and expression patterns in both poplar species under stress. We overexpressed and suppressed PagMTC, a homolog of METTL4 in 84K poplar, and found that the overexpression lines exhibited enhanced salt tolerance. The salt-tolerant genes PagCERK1, PagNCED3a, PagNCED3b, PagCAT2, and PagPOD16 were found to be regulated through PagMTC-mediated hypermethylation, as determined by MeRIP-seq, MeRIP-qPCR, and mRNA stability assay. It was also observed that hypermethylation of genes such as XTH15, CAT2, and AT-HSFB2A after salt stress in wild-type 84K poplar may be mediated by PagMTC. This study reveals the important role of m6A modification in response to salt stress in poplar and also identifies a potential molecular target for breeding trees with enhanced stress tolerance.

Soil salinization is one of the major abiotic stresses affecting global crop productivity and agricultural sustainability. Barley (Hordeum vulgare L.) is one of the most salt-tolerant cereal crops, so it is possible and imperative to explore the elite genes or genetic factors contributing to salt tolerance. Here, we identified HvCBP60-8, a member of the CBP60 transcription factors, acting as a positive regulator of salt tolerance in barley. CRISPR/Cas9-induced loss-of-function mutants of HvCBP60-8 showed more sensitivity to salt stress, accompanied by elevated Na⁺ accumulation in shoots due to enhanced root-to-shoot Na⁺ translocation. Transcriptome analysis of wild-type and cbp60-8 mutants revealed three receptor-like kinase genes (HvRLK3/4/5) as downstream targets of HvCBP60-8. Dual-LUC assay confirmed that HvCBP60-8 could directly activate the expression of HvRLK3/4/5 by binding to their promoters. RT-qPCR analysis showed that HvCBP60-8 up-regulated the expression of three key ion transporter genes (HvHAK1, HvNHX1, and HvHKT1;1), resulting in improved K⁺/Na⁺ homeostasis under salt stress. The results also revealed the distinct variation of HvCBP60-8 haplotypes in a natural population, with cultivated barley showing the dominant variation, probably caused by natural and artificial selection. In conclusion, HvCBP60-8 is a pivotal transcriptional regulator of salt tolerance in barley through responding to receptor-like kinase signaling and modulating the expression of genes encoding key ion transporters. The current results provide novel genetic targets for crop breeding to develop varieties with high salt stress tolerance.