The Plant Journal最新文献

2-Phenylethylchromones (PECs) and 2-styrylchromones (SCs) are the primary components responsible for the delightful fragrance and bioactivity of agarwood, a highly valuable aromatic resinous heartwood. PECs are derived from a common precursor with a diarylpentanoid skeleton (C₆–C₅–C₆). However, the biosynthesis of SCs remains unclear. In this study, based on the successful conversion of the PEC skeleton, rather than a dehydrogenated diarylpentanoid, into SCs by Aquilaria sinensis suspension cells, we demonstrated that double bond formation of the styryl group in SCs occurs after the creation of the PEC skeleton, not before this step from a dehydrogenated diarylpentanoid precursor. Through transcriptomic data mining, transient expression in Nicotiana benthamiana and A. sinensis suspension cells, we identified a new 2-oxoglutarate-dependent oxygenase (As2OG1) that plays a crucial role in the conversion of PECs into SCs. Further protein structure prediction and mutagenesis studies, combined with probing of the catalytic potential of As2OG1 using chemically synthesized hydroxylated intermediates, suggested that As2OG1 possibly uses diradical or carbocation intermediates, rather than hydroxylated intermediates, to install double bonds in SCs. The results not only provide insights into the molecular mechanism of agarwood formation but also facilitate the overproduction of pharmaceutically important SCs using metabolic engineering approaches.

Rice is a staple food for billions of people but also a major source of methane emissions, contributing approximately 10% of global agricultural methane. Therefore, this study aimed to conduct a correlation analysis of various traits gathered from years of research on the 120 Cheongcheong Nagdong Double Haploid (CNDH) population to identify key traits responsible for methane emission in rice. This study focused on practical plant traits, including culm length, spikelets per panicle, and grain weight, which have a positive correlation with methane emission. Shorter culm lengths produce less biomass, thereby reducing the organic matter available to feed methane-producing microbes. Increasing the number of spikelets per panicle increase boosts grain production, thereby reducing the development of root exudates that contribute to methane production. Our results indicate a positive correlation (r = 0.51) between grain weight and methane emissions, suggesting that selecting for heavier grains may actually increase methane emissions. Based on these features, we propose an rice ideotype variety that possibly minimizes the rice plant methane emissions while maintaining a high yield. This paper suggests that future studies should be extended to validate these current findings and explore the genetic components and ecological aspects of methane emissions to improve methane management in sustainable rice farming systems.

RNA decay is a pervasive process in eukaryotic cells. Viruses utilize the host cell's intracellular machinery to gain access to essential molecules and subcellular structures required for infection during the pathogenesis process. The study demonstrates that turnip crinkle virus (TCV) infection enhances the expression of Arabidopsis Dcp1 (AtDcp1), which negatively regulates the accumulation of TCV RNA, indicating its involvement in antiviral defense. Nevertheless, TCV circumvents the antiviral defense based on RNA decay, as indicated by the capsid protein (CP) of TCV stabilizing the known nonsense-mediated RNA decay-targeted transcripts. In vivo, CP physically interacts with AtDcp1, promoting AtDcp1 degradation via ubiquitination pathway. This is evidenced by the observation that the degradation is inhibited by 26S proteasome inhibitors. Furthermore, CP elevates the polyubiquitination of Dcp1-Flag. These data indicate that CP suppresses RNA decay by interacting with AtDcp1 and mediating its degradation through the 26S proteasome pathway, effectively suppressing antiviral RNA decay. This study uncovers a previously unidentified virulence strategy in the ongoing conflict between plants and TCV.

Wheat (Triticum aestivum L.) is one of the world's main food crops and the largest phosphorus (P) fertilizer consumer globally. However, the molecular mechanism of P distribution in wheat remains largely unknown. This study investigated the TaSULTR gene family and functionally characterized TaSPDT (TaSULTR3;4). Thirty-three TaSULTR genes were identified and divided into four groups. These genes contained three tandem duplications and 28 segmental duplications. TaSPDT was localized on the plasma membrane and demonstrated P transport activity. TaSPDT was mainly expressed at nodes, and its expression was elevated under low P conditions. TaSPDT was distributed on the xylem and phloem of enlarged and diffuse vascular bundles at nodes, as well as on the parenchyma cell bridge between vascular bundles. TaSPDT knockout reduced P distribution to young leaves but increased it in older leaves during the vegetative stage under low P availability. P uptake by roots, transfer to above-ground tissues, and redistribution within aerial organs were unaffected. At the reproductive stage, TaSPDT knockout notably diminished P allocation to grains, resulting in a significant decrease in grain yield, particularly under P-deficient conditions. These results suggest that TaSPDT mediates the transmembrane transport of P from the xylem to the phloem at the nodes, resulting in the preferential distribution of P to grains. This study enables a better understanding of the TaSULTR gene family and P distribution in wheat.

Phosphorus in the soil is easily chelated into forms that are unavailable to plants, leading to phosphorus deficiency, which severely affects the growth, development, and fruit quality of apple trees. To address phosphorus deficiency, we used four different arbuscular mycorrhizal fungi (AMF) to investigate their effects on the growth and development of apple rootstocks and phosphorus uptake in the soil. We identified Glomus mosseae (Gm) fungi as the most effective AMF for promoting growth and found that under phosphorus-deficient conditions, inoculating with Gm fungi promoted the growth of the above-ground parts of the plants and phosphorus absorption, while it inhibited root growth. After inoculating with Gm fungi, we found phosphorus starvation response factors (PHRs) and auxin response factors (ARFs) were upregulated. Knockdown of MdPHR2 or MdARF6-4 resulted in decreased root arbuscular structures, total mycorrhizal colonization rate, and root phosphorus content, indicating that MdPHR2 and MdARF6-4 positively regulate the symbiosis of Gm fungi and phosphorus absorption. In contrast, overexpressing MdARF6-4 led to reduced root development but increased root phosphorus content under Gm fungi inoculation, suggesting that MdARF6-4 is involved in Gm-mediated phosphorus absorption and root development. Moreover, both MdPHR2 and MdARF6-4 directly bound to the promoter area of the downstream phosphorus transporter MdPHT1;13, and these two transcription factors interacted with each other in vivo and in vitro. In summary, our study demonstrates that the interaction between MdPHR2 and MdARF6-4 synergistically regulates the Gm symbiosis and the transcription of MdPHT1;13, thereby promoting phosphorus absorption in apple rootstocks.

Plant flavonols act primarily as ultraviolet radiation absorbers, reactive oxygen species scavengers, and phytoalexins, and they contribute to biotic and abiotic stress tolerance in plants. Banana (Musa acuminata), an herbaceous monocot and important fruit crop, accumulates flavonol derivatives in different organs, including the edible fruit pulp. Although flavonol content varies greatly in different organs, the molecular mechanisms involving transcriptional regulation of flavonol synthesis in banana are not known. Here, we characterized three SG7-R2R3 MYB transcription factors (MaMYBFA1, MaMYBFA2, and MaMYBFA3) and heat shock transcription factor (MaHSF11), to elucidate the molecular mechanism involved in transcriptional regulation of flavonol biosynthesis in banana. MaMYBFA positively regulates flavonol synthase 2 (MaFLS2) and downregulates MaFLS1. We show these transcription factors to be weak regulators of flavonol synthesis. Overexpression of MaHSF11 enhances flavonol contents, particularly that of myricetin, and promotes flavonol B-ring hydroxylation, which contributes to the diversity of flavonol derivatives. MaHSF11 directly interacts with the MaFLS1 and flavonoid 3′,5′-hydroxylase1 (MaF3′5′H1) promoters, both in vitro and in vivo. MaHSF11 activates the expression of MaDREB1 directly, which is known to promote cold and chilling tolerance in banana fruit. Overall, our study elucidates a regulatory mechanism for flavonol synthesis in banana and suggests possible targets for genetic optimization to enhance nutritional value and stress responses in this globally important fruit crop.

Organic acids are major contributors to the flavor of fleshy fruits. In kiwifruit, the Al-ACTIVATED MALATE TRANSPORTER gene (AcALMT1) is key to the accumulation of citrate, while factors driving malate metabolism remain largely unknown. During kiwifruit (Actinidia chinensis cv “Hongyang”) development, a rapid decline of malate content was observed between 6 and 12 weeks after full bloom (WAFB), which was studied using RNA-seq analysis. Co-expression network analysis indicated that expression of the chloroplast localized AcPNAD-MDH1 (Plastid-Localized NAD-Dependent Malate Dehydrogenase) negatively correlated with malate content. Overexpression of AcPNAD-MDH1 in kiwifruit resulted lower malate and citrate content in leaves. Among 15 transcription factors that are highly correlated with the expression of AcPNAD-MDH1, AcSQBP9 (SQUAMOSA PROMOTER-BINDING PROTEIN) was shown to directly bind the promoter of AcPNAD-MDH1 to repress transcriptional activity. Moreover, targeted CRISPR-Cas9-induced mutagenesis of AcSQBP9 in kiwifruit produced a significant decrease in malate and citrate, accompanied by an increase in AcPNAD-MDH1 expression. Both PNAD-MDH and SQBP have not been widely studied in fruit metabolism, so the present omics-oriented study provides insights for both kiwifruit and general plant organic acid metabolism.