Planta最新文献

Main conclusion: The microbial terpene synthase-like of the moss Sanionia uncinata displays the convergent evolution of a rare plant metabolite amorpha-4,11-diene synthesis. Despite increasing demand for the exploration of biological resources, the diversity of natural compounds synthesized by organisms inhabiting various climates remains largely unexplored. This study focuses on the moss Sanionia uncinata, known as a predominant species within the polar climates of the Antarctic Peninsula, to systematically explore its metabolic profile both in-field and in controlled environments. We here report a diverse array of moss-derived terpene volatiles, including the identification of amorpha-4,11-diene, a rare sesquiterpene compound that is a precursor for antimalarial drugs. Phylogenetic reconstruction and functional validation in planta and in vitro identified a moss terpene synthase, S. uncinata microbial terpene synthase-like 2 (SuMTPSL2), which is associated with amorpha-4,11-diene production. We demonstrate that expressing SuMTPSL2 in various heterologous systems is sufficient to produce amorpha-4,11-diene. These results highlight the metabolic diversity in Antarctica, but also provide insights into the convergent evolution leading to the synthesis of a rare plant metabolite.

Main conclusion: The contribution of p-coumarate β-oxidation and kaempferol cleavage to the pools of glycosylated, free and cell wall-bound 4-hydroxybenzoate is organ-dependent in Arabidopsis. 4-Hydroxybenzoate (4-HB) is a vital precursor for a number of plant primary and specialized metabolites, as well as for the assembly of the plant cell wall. In Arabidopsis, it is known that 4-HB is derived independently from phenylalanine and tyrosine, and that the metabolism of phenylalanine into 4-HB proceeds via at least two biosynthetic routes: the β-oxidation of p-coumarate and the peroxidative cleavage of kaempferol. The precise contribution of these precursors and branches to 4-HB production, however, is not known. Here, we combined isotopic feeding assays, reverse genetics, and quantification of soluble (i.e., free and glycosylated) and cell wall-bound 4-HB to determine the respective contributions of phenylalanine, tyrosine, β-oxidation of p-coumarate, and peroxidative cleavage of kaempferol to 4-HB biosynthesis in Arabidopsis tissues. Over 90% of 4-HB was found to originate from phenylalanine in both leaves and roots. Soluble 4-HB level varied significantly between organs, while the proportion of cell wall-bound 4-HB was relatively constant. In leaves and flowers, glycosylated and cell wall-bound 4-HB were the most and least abundant forms, respectively. Flowers displayed the highest specific content of 4-HB, while free 4-HB was not detected in roots. Although p-coumarate β-oxidation and kaempferol catabolism were found to both contribute to the supply of 4-HB in all tissues, the proportion of kaempferol-derived 4-HB was higher in roots than in leaves and flowers. Within the β-oxidative branch, p-coumaroyl-CoA ligase 4-CL8 (At5g38120) bore a preponderant role in the production of soluble and cell wall-bound 4-HB in leaves, while p-coumaroyl-CoA ligase At4g19010 appeared to control the biosynthesis of soluble 4-HB in flowers. Furthermore, analysis of a series of Arabidopsis T-DNA mutants corresponding to the three major UDP-glucosyltransferases known to act on 4-HB in vitro (UGT75B1, UGT89B1, and UGT71B1) showed that none of these enzymes appeared in fact to have a significant role in the glycosylation of 4-HB in vivo.

Main conclusion: Association analysis identified 77 marker-trait associations (MTAs) for PUE traits, of which 10 were high-confidence MTAs. Candidate-gene mining and in-silico expression analysis identified 13 putative candidate genes for PUE traits. Bread wheat (Triticum aestivum L.) is a major cereal crop affected by phosphorus (P) deficiency, which affects root characteristics, plant biomass, and other attributes related to P-use efficiency (PUE). Understanding the genetic mechanisms of PUE traits helps in developing bread wheat cultivars that perform well in low-P environments. With this objective, we evaluated a bread wheat panel comprising 304 accessions for 14 PUE traits with high-throughput phenotyping under low-P and optimum-P treatments and observed a significant genetic variation among germplasm lines for studied traits. Genome-wide association study (GWAS) using 14,025 high-quality single-nucleotide polymorphisms identified 77 marker-trait associations (MTAs), of which 10 were chosen as high-confidence MTAs as they had > 10% phenotypic variation with logarithm of odds (LOD) scores of more than five. Candidate-gene (CG) mining from high-confidence MTAs identified 180 unique gene models, of which 78 were differentially expressed (DEGs) with at least twofold change in expression under low-P over optimum-P. Of the 78-DEGs, 13 were thought to be putative CGs as they exhibited functional relevance to PUE traits. These CGs mainly encode for important proteins and their products involved in regulating root system architecture, P uptake, transport, and utilization. Promoter analysis from 1500 bp upstream of gene start site for 13 putative CGs revealed the presence of light responsive, salicylic-acid responsive, gibberellic-acid (GA)-responsive, auxin-responsive, and cold responsive cis-regulatory elements. High-confidence MTAs and putative CGs identified in this study can be employed in breeding programs to improve PUE traits in bread wheat.

Main conclusion: During evolution, similar vectors of adaptive radiation may have evolved in the subtribe Malaxidinae. This was manifested in homologous series of variability in suspensor shape and seed coat ultrasculpture in clades of terrestrial and epiphytic orchids. The present study examines the variability of embryonic traits across clades and subclades of subtribe Malaxidinae (Orchidaceae), previously identified by molecular genetic data. Ovules and seeds from fruits of orchids of the genera Crepidium, Liparis (sections Cestichis and Blepharoglossum), Dienia, and Oberonia were examined by confocal laser microscopy with fluorescent dye staining. The branched or rounded suspensor in the studied species was unicellular and originated from the nondividing basal cell cb. The elongated or flattened transmission structure of one or two cells was located at the junction of the suspensor and the embryo proper. Two species (Oberonia gammiei and Liparis elliptica) were found to have unitegmal ovules. Three morphological groups of seeds were identified based on the shape and sculpture of the periclinal cell wall. A comparative analysis of the embryological characters in Malaxidinae species reveals that the lobed suspensor is a homoplasy present in different subclades of terrestrial and epiphytic orchids. The flat transmission cell is an apomorphy in the Cestichis subclade. Similarly, the independent formation of the unitegmal ovule occurred in two subclades of epiphytic orchids. The results of our study suggest that similar adaptive radiation vectors may have evolved in the subtribe Malaxidinae in the orchids we studied.

Main conclusion: The metabolomic of the Italian endemic species Stachys italica was investigated and potential positive metabolites for human's health were detected, quantified and discussed in relation to its synecology. Stachys italica is a species endemic to central-southern Italy, traditionally used for human consumption. The present research reports the results of a phytosociological study of this species in two southern regions of Italy (Apulia and Calabria). The collected plant material was used to make two types of extracts: hot water infusion to evaluate the use of this plant as tea and hydroalcoholic extraction to evaluate the use of it in herbal liqueur preparation. The extracts obtained by the hot water infusion had a values of total polyphenols and antioxidant capacity similar to values found in black tea. The analysis of non-volatiles compounds revealed the presence of biologically active substances like lavandulifolioside, verbascoside, and methoxyflavones. The analysis of volatiles fraction of metabolites demonstrated fifty-three volatiles compounds in the plant aerial part, 19 of which belonging to monoterpenoids, and 17 to the class of sesquiterpenoids. Among them, α-pinene, β-pinene, cis-ocimene, limonene and t-caryophyllene, were the most abundant compounds. The results were compared with already published results and referred to other similar species (such as Sideritis syriaca) which represent herbal mixtures usually collected and used as "mountain tea" in the Balkans and Eastern European countries.

Main conclusion: SUMOylation of SLR1 at K2 protects productivity under salt stress, possibly by modulation of SLR1 interactome. DELLA proteins modulate GA signaling and are major regulators of plant plasticity to endure stress. DELLAs are mostly regulated at the post-translational level, and their activity relies on the interaction with upstream regulators and transcription factors (TFs). SUMOylation is a post-translational modification (PTM) capable of changing protein interaction and has been found to influence DELLA activity in Arabidopsis. We determined that SUMOylation of the single rice DELLA, SLENDER RICE1 (SLR1), occurs in a lysine residue different from the one identified in Arabidopsis REPRESSOR OF GA (RGA). Artificially increasing the SUMOylated SLR1 levels attenuated the penalty of salt stress on rice yield. Gene expression analysis revealed that the overexpression of SUMOylated SLR1 can regulate GA biosynthesis, which could partially explain the sustained productivity upon salt stress imposition. Furthermore, SLR1 SUMOylation blocked the interaction with the growth regulator YAB4, which may fine-tune GA20ox2 expression. We also identified novel SLR1 interactors: bZIP23, bHLH089, bHLH094, and OSH1. All those interactions were impaired in the presence of SUMOylated SLR1. Mechanistically, we propose that SUMOylation of SLR1 disrupts its interaction with several transcription factors implicated in GA-dependent growth and ABA-dependent salinity tolerance to modulate downstream gene expression. We found that SLR1 SUMOylation represents a novel mechanism modulating DELLA activity, which attenuates the impact of stress on plant performance.