The Plant Journal最新文献

Identifying the selectivity of cadmium (Cd) and manganese (Mn) in transporters has long been a challenging scientific issue. Here, we identified the gene SaNRAMP5 from Solanum americanum, an orthologue of OsNRAMP5. SaNRAMP5 is predominantly expressed in root and localizes to the plasma membrane (PM). Knockout of SaNRAMP5 significantly reduced Cd accumulation in nightshade, while its overexpression in Arabidopsis increased Cd uptake in roots. Given the close relationship between nightshade and vegetables like potatoes, tomatoes, eggplants, and peppers, we compared the Cd absorption capabilities of NRAMP5 homologs in these species. Our results indicated that SaNRAMP5 exhibited a greater Cd uptake capacity than its homologs within the Solanaceae family. Interestingly, the Mn uptake capacities of these NRAMP5s varied independently of their Cd uptake capacities. Amino acid sequence analysis revealed that the N-terminal STNP residues, which mediate phosphorylation in SaNRAMP5, are crucial for the selective uptake of Cd and Mn. Mutating these STNP residues to a non-phosphorylatable form, SaNRAMP5(AANP), resulted in reduced Cd uptake without affecting Mn uptake. Conversely, StNRAMP5 and SlNRAMP5, which naturally lack STNP residues, demonstrated enhanced Cd uptake upon the introduction of STNP but not AANP. Notably, neither the introduction of STNP nor AANP affected their Mn uptake capacities. The reduced Cd uptake of SaNRAMP5(AANP) without compromising Mn uptake was attributed to alterations in PM localization due to continuous Cd exposure, rather than Mn exposure. Our findings provide novel insights into phosphorylation-mediated selective uptake of Cd and Mn, paving the way for engineering low-Cd crops without compromising yield.

The aromatic composition of lignin greatly influences the potential utility of lignocellulosic biomass. Previously, we generated transgenic rice plants with altered lignin aromatic composition and enhanced biomass utilization properties by suppressing the expression of p-COUMAROYL ESTER 3-HYDROXYLASE (C3′H). While RNAi-derived C3′H-knockdown lines displayed relatively normal growth with substantially augmented levels of p-hydroxyphenyl-type lignin units, genome-edited C3′H-knockout lines exhibited severely impaired growth phenotype, leading to arrested seedling development. In this study, we further characterized the genome-edited C3′H-knockout rice by analyzing gene expression and phenolic metabolite profiles alongside phenotypic traits and cell wall lignin structure. The seedlings of the C3′H-knockout rice displayed irregular vasculature and ectopic lignification. RNA-sequencing analysis detected widespread changes in the expression of genes associated with plant growth, hormone biosynthesis and signaling, and stress responses in the C3′H-knockout rice. Overall, our data suggested that C3′H disruption activates metabolic sensor-mediated signaling pathways, which in turn regulate phenylpropanoid metabolism. In line with this, phenolic metabolite profiling of the C3′H-knockout rice revealed not only shifts in monolignol-associated phenylpropanoids but also reductions in flavonoids and salicylic acid derivatives. Moreover, changes in the aromatic composition of the mutant lignin and phenolic metabolites indicated the presence of parallel monolignol pathways enabling rice to produce guaiacyl- and syringyl-type monolignol derivatives in the absence of C3′H activity. Our findings contribute to a deeper understanding of the mechanisms underlying the growth defects of lignin-modified mutants, with implications for optimizing the utility of grass lignocellulose.

Fritillaria unibracteata var. wabuensis is an important resource plant for the famous traditional Chinese medicine Fritillariae cirrhosae bulbus (“Chuanbeimu” in Chinese). F. cirrhosae bulbus is the dried bulbs of several species from Fritillaria genus, with isosteroidal alkaloids components assumed as the bioactive ingredients. However, the biosynthesis pathway of isosteroidal alkaloids remains elusive. Here, we adopted F. unibracteata var. wabuensis as a material to identify genes involved in the biosynthesis of isosteroidal alkaloids. We first constructed the multi-tissue metabolome and transcriptome dataset of F. unibracteata var. wabuensis. Interestingly, imperialine-3-β-d-glucoside, an isosteroidal glycoalkaloid, was found to be the major tissue-specific accumulated alkaloid. Through phylogenetic and co-expression analysis, we identified two UDP-glucosyltransferases from UGT73 family catalyzing 3-O-glucosylation of isosteroidal and steroidal alkaloids: imperialine 3-O-glucosyltransferase (FuwI3GT) can use both isosteroidal alkaloid imperialine and steroidal alkaloid solanidine as substrates, while solanidine 3-O-glucosyltransferase (FuwS3GT) can only use steroidal alkaloid solanidine as a substrate. We further approved that the W201 residue of FuwI3GT determined its substrate preference of isosteroidal alkaloids. Overall, our results identified enzymes involved in 3-O-glucosylation of isosteroidal and steroidal alkaloids in F. unibracteata var. wabuensis and paved the way to fully elucidate the isosteroidal alkaloid biosynthesis pathway in Fritillaria species.

Camellia sinensis is an industrial crop characterized by specific secondary metabolites, which provide numerous benefits to human health. Previous researches reveal that the secondary metabolism of tea plants is significantly affected by various environmental factors, especially light intensity. However, the epigenetic mechanism underlying these high light-induced changes remains systematic research. In this study, physiological analysis suggested that increased photosynthetic product was rapidly converted into other organic compounds in adaptation to high light. The metabolite landscape by widely targeted metabolome revealed 219 differentially accumulated metabolites (DAMs) in high light, with substantial upregulated DAMs accumulated in ‘amino acids and derivatives’ and ‘alkaloids’. The landscape of nine crucial histone modifications showed the distribution diversity in the genome and the complex relationship with gene expression. Integrated analysis of stomatal development, metabolome, epigenome, and transcriptome indicated that the dynamics of histone modifications (H3K4ac, H3K4me3, H3K9ac, H3K9me2, H3K27ac, and H3K27me3) on gene regions were closely related to the expression of regulatory genes in stomatal development and enzyme genes in secondary metabolic pathways, leading to stomatal density and metabolite changes in high light. Furthermore, H3K27ac and H3K27me3 were identified as key histone modifications, regulating critical genes under high light, including CsEPFL9, CsYODAb, CsF3′Hb, CsCHSc, CsANRa, CsDFRb-2, CsAlaDC, CsAAP1, CsGGT2, CsXMPP, Cs7-NMT, CsPORC, and CsPSY. These results suggest the pivotal role of histone modifications in the high light-induced stomatal density and secondary metabolite changes of tea plants.

Photosystem II (PSII) is one of the most thermosensitive components of photosynthetic apparatus in higher plants. Heat-inactivation of PSII may be followed by dissociation of antenna proteins, however, the fate and regulation mechanism of detached antenna proteins during this process remains unclear. Here, we investigate the regulation mechanism of two minor antenna proteins CP24 and CP29 during heat acclimation via the study on a thylakoid protein BCM1. BCM1 is distributed in both grana cores (GC) and stroma lamellae of thylakoids. However, heat stress induced its accumulation in grana cores but not stroma lamellae. Deficiency of BCM1 leads to the decline of plant resilience to heat stress, which results from the accelerated degradation of CP24 and CP29 in vivo. Heat stress induces a redistribution of CP24 and CP29 from the grana cores to the stroma lamellae, a shift that is exacerbated in bcm1 mutants, suggesting that migration of detached antennae proteins between thylakoid subcompartments may contribute to their degradation during heat acclimation. As an integral thylakoid protein, BCM1 physically interacts with CP24 and CP29. We propose that BCM1 serves as a stabilizing “anchor”, effectively sequestering CP24 and CP29 within the grana cores thereby reducing their exposure to degradation in the stroma lamellae.

Lint percentage is an important component of cotton yield traits and an important economic indicator of cotton production. The initial stage of fiber development is a critical developmental period that affects the lint percentage trait, but the genetic regulation of the initial stage of fiber development needs to be resolved. In this study, we used a genomewide association study (GWAS) to identify 11 quantitative trait loci (QTLs) related to lint percentage and identified a total of 13 859 expression QTL (eQTLs) through transcriptome sequencing of 312 upland cotton accessions. Candidate genes for improving the lint percentage trait were identified through transcriptome-wide association study (TWAS), colocalization analysis, and differentially expressed gene analysis. We located nine candidate genes through the TWAS, and prioritized two key candidate genes (Ghir_A12G025980 and Ghir_A12G025990) related to lint percentage through colocalization and differential expression analysis. We showed that two eQTL hotspots (Hot26 and Hot28) synergistically participate in regulating the biological pathways of fiber initiation and development. Additionally, we unlocked the potential of genomic variants in improving the lint percentage by aggregating favorable alleles in accessions. New accessions suitable for improving lint percentage were excavated.