The Plant Journal最新文献

In soybean breeding, using the recessive male-sterile ms5 gene, derived from fast neutron mutagenesis, for recurrent selection is advantageous because of the d2 locus, which controls cotyledon color in mature seeds and can be used as a phenotypic selection marker for ms5 male sterility. However, occasional self-fertilization occurs because of the elimination of d2 linkage and instability of male sterility. Elucidating the mechanism and the gene responsible for ms5 male sterility may resolve these problems. Using fine mapping with 15 simple sequence repeat (SSR) markers, we narrowed down the candidate ms5 locus to a 54-kbp region. Bulked-DNA analysis using next-generation sequencing revealed a deletion as a candidate variation in the region. This 15-bp deletion and a nucleotide substitution were identified in intron 1 of MutS homolog (GmMSH4), which modulates chromosomal recombination in meiosis. The ms5 transcript contained a novel exon with a premature termination codon. This exon originated from an alternative splice acceptor site caused by the deletion and nucleotide substitution, disrupting gene function. Co-segregation of male sterility with five independent mutations in GmMSH4 was confirmed using progeny of mutant lines. Mutations in GmMSH4 led to biased DNA partitioning during meiosis, resulting in collapsed or enlarged pollen and suggesting that ms5 male sterility is caused by the failure of pollen formation during meiosis due to the loss of function of GmMSH4. These findings could help explain the mechanism of instability of ms5 male sterility and improve the efficiency of recurrent selection using DNA markers in soybean breeding.

Drought is a major abiotic stress that impairs plant growth and development. Developing drought-tolerant crop varieties is an important goal of breeders. Transcription factors belonging to the DNA-binding with one zinc finger (Dof) family regulate plant stress responses and development. However, the roles and regulatory mechanisms of Dof2.1 members in plant stress tolerance are still unclear. Here, we cloned the IbDof2.1 gene from sweetpotato and found that its overexpression significantly enhanced drought tolerance of sweetpotato, whereas IbDof2.1-RNA interference (RNAi) plants displayed the opposite phenotype. The IbDof2.1-overexpression plants showed increased abscisic acid (ABA) and proline contents and stomatal sensitivity to ABA and decreased H₂O₂ accumulation. Furthermore, we found that IbDof2.1 interacted with ABA-binding factor 2 (IbABF2) and promoted the expression of the proline biosynthesis gene IbP5CS1 to increase proline content, further activating the reactive oxygen species (ROS) scavenging system. These results suggest that the IbDof2.1–IbABF2 module induces stomatal closure and activates the ROS scavenging system by regulating ABA responses and proline biosynthesis to enhance drought tolerance in sweetpotato. Our findings provide novel insights into the roles and regulatory mechanisms of Dof2.1 in plants.

Apple leaf spot disease, caused by Alternaria alternata, significantly impacts apple production. Phosphorus plays a crucial role in maintaining the healthy growth of plants and enhancing their defense against pathogens. Both low-affinity and high-affinity phosphate transporters are important proteins involved in the response to phosphate starvation and increasing phosphate content. The difference is that the former does not easily cause excessive accumulation of phosphorus, leading to phosphorus toxicity in plants. Currently, the defense mechanisms mediated by low-affinity phosphate transporters in apples are not well understood. In this study, we identified two low-affinity phosphate transporters, PHT5-2 and PHT5-3. Compared to the control, although the overexpression of PHT5-2 and PHT5-3 increased phosphorus content in the plants, it did not result in growth defects. Furthermore, the overexpression of PHT5-2 and PHT5-3 led to increased callose deposition, enhancing resistance to A. alternata. We verified that the non-coding sRNA-miR827 binds to the mRNA of PHT5-2 and PHT5-3 via complementary base pairing and suppresses their expression by cleaving the 5′ UTR regions using 5′ RLM-RACE and N. benthamiana co-transformation assays. Apple plants overexpressing miR827 showed significantly reduced phosphorus content and severe growth defects, accompanied by decreased callose deposition and weakened disease resistance. In summary, our research results reveal the mechanism by which miR827 regulates phosphate transporters involved in the defense of apples against A. alternata.

Citric acid in plant cells is crucial for growth as it serves as a precursor to multiple essential compounds. It also helps plants tolerate high temperatures. However, the mechanisms remain unclear regarding how citric acid balances its role in promoting growth and protecting against stress. We identified an ACLA protein, a subunit of ATP citrate lyase (ACL) in pepper (Capsicum annuum), that converts cytosolic citric acid into acetyl-CoA. Silencing ACLA reduced citric acid metabolites, leading to stunted growth and decreased heat tolerance. Conversely, ACLA-2 overexpression increased acetyl-CoA metabolites but reduced citric acid levels, which also led to reduced heat tolerance. However, applying exogenous citrate significantly improved the heat tolerance of ACLA-overexpressing plants compared with wild-types. This suggests that citric acid plays a dual role in the synthesis of structural components and in enhancing heat stress resistance. When plants are subjected to heat stress, ACL is rapidly degraded within 1 min. Treatments with E64d and MG132 demonstrated that autophagy and the 26S proteasome pathway contribute to this degradation. This dynamic degradation precisely regulates the dual role of ACL in growth and stress responses, indicating a novel mechanism by which plant cells rapidly adapt to environmental changes through the degradation of key enzymes.

RNA-binding proteins (RBPs) have emerged as key players in posttranscriptional gene regulation, yet their full scale role in fruit ripening remains to be fully elucidated. However, due to the complex structure and composition of fruit tissue, exploring RBPs in fruits still faces many challenges. Here, we optimized the plant phase extraction method and successfully applied it to tomato fruits for the unbiased excavation of RBPs in fruits, this method were named as “plant phase extraction in tomato fruit” (termed tfPPE). We yielded a comprehensive candidate RNA-binding proteome (RBPome) composed of 230 proteins and disclosed that approximately 66% of them were unconventional RBPs. Validation of the RNA-binding activities of six candidate RBPs unveiled that metabolic enzymes function as moonlighting RBPs. Furthermore, combined with transcriptome analysis, we identified 41 candidate RBPs associated with fruit ripening. Remarkably, we proposed that SlER21 and SlFER1 play significant roles in fruit coloring and ripening process. Taken together, these results demonstrate that tfPPE was an impactful approach for unbiased excavation RBPs in fruits and pave the way for investigating RBP functions in fruit-ripening regulatory network.

Safflower, a traditional Chinese medicine, is renowned for its efficacy in promoting blood circulation and alleviating blood stasis. Its principal bioactive components are flavonoids, which predominantly exist as flavonoid glycosides. Glycosyltransferases, as downstream post-modification enzymes in the biosynthesis of these active glycosides, are of considerable research interest. This study leverages transcriptome data from safflower to identify a glycosyltransferase gene, UGT95A2, which was subjected to comprehensive bioinformatics and enzymatic property analyses. In vitro enzymatic assays demonstrated that UGT95A2 catalyzes the glycosylation of flavonoids with an ortho hydroxyl group on the B-ring, generating 3′-OH glycosylated products, such as luteolin, taxifolin, catechin, butin, and eriodictyol. When the ortho hydroxyl groups are located on the A-ring, UGT95A2 instead catalyzes the formation of 6-O-glucosides, as observed for baicalein and 6,7,4′-trihydroxyisoflavone. Validation of in vitro activity showed that overexpression of UGT95A2 enhances the luteolin-3′-O-glucoside content in safflower protoplasts and tobacco leaves. Molecular modeling and site-directed mutagenesis studies indicated that E328 is a critical active site for 3′-hydroxyl glycosylation, while D444 is essential for the enzyme's catalytic activity in generating disaccharides. The identification of the novel glycosyltransferase UGT95A2 provides a foundation for further elucidation of the glycosylation processes of flavonoid glycosides and offers a new biotechnological approach for the production of flavonoid 3′-O-glucosides. This advancement has significant implications for expanding the repertoire of glycosylation enzymes and offers valuable insights for the directed modification of engineering enzymes.