Journal of Plant Research最新文献

Phenotypic plasticity may allow plant species to cope with environmental variability that influences plant growth and may limit the distribution of a species. The present study investigated the morphophysiology and phenotypic plasticity responses due to light and water variability of young Dimorphandra exaltata plants, an endemic threatened tree from the Atlantic Forest. After emergence, plants were grown in two light conditions: shading (70%) and full sun. At 160 days old, we measured chlorophyll a fluorescence, chlorophyll indices, and biomass allocation. Afterward, the plants were subdivided into two water regimes: irrigation vs suspension of irrigation. At 310 days old, morphophysiological measurements and stem water potential were taken. D. exaltata plants showed higher specific leaf area (SLA, 160 days old) and chlorophyll b (310 days old) under shading. Over time, plants under shading showed a decrease in SLA. Also, there was a decrease in the leaf area ratio in both light treatments and an increase in the phenotypic plasticity index. Even showing morphological adjustments to light and water deficit, the higher biomass allocation to roots at the expense of the aboveground part could impair the growth of young plants in understory areas. The phenotypic plasticity presented by D. exaltata does not guarantee that the species can withstand severe disturbance while maintaining normal development. Therefore, it is important to understand the effects of ecosystem fragmentation and water variation and their impacts on the maintenance of species in their areas of occurrence, especially endangered species such as D. exaltata.

Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) is considered to be a key enzyme in lignin biosynthesis, which can catalyze cinnamyl aldehyde to produce cinnamyl alcohol. In this study, three putative CADs were characterized from the liverwort Haplomitrium mnioides. The sequence alignment and phylogenetic analysis revealed that HmCADs belonged to a multigene family, with three HmCADs belonging to class II, class III, and class IV, respectively. In vitro enzymatic studies demonstrated that HmCAD2 exhibited high affinity and catalytic activity towards five cinnamyl aldehydes, followed by HmCAD3 with poor catalytic activity, and HmCAD1 catalyzed only the reaction of p-coumaryl aldehyde and coniferyl aldehyde with extremely low catalytic capacity. Protein-substrate binding simulations were performed to investigate the differences in catalytic activity exhibited when proteins catalyzed different substrates. Furthermore, distinct expression patterns of three HmCADs were identified in different plant tissues. Subcellular localization tests confirmed that HmCAD1/2/3 was located in the cytoplasm. The simulated responses of HmCADs to different stresses showed that HmCAD1 played a positive role in coping with each stress, while HmCAD2/3 was weak. These findings demonstrate the diversity of CADs in liverwort, highlight the divergent role of HmCAD1/2/3 in substrate catalysis, and also suggest their possible involvement in stress response, thereby providing new insights into CAD evolution while emphasizing their potential distinctive and collaborative contributions to the normal growth of primitive liverworts.

Cassava common mosaic virus (CsCMV) is a potexvirus that impairs chloroplast and metabolism, causing significant yield losses to cassava crops. Crop yield depends on diel rhythms, influencing carbon allocation and growth, and sugar signaling also impacting light-dark rhythms. This study aimed to elucidate the early impact of CsCMV infection on diel carbon allocation, metabolism, and defense mechanisms in both source and sink cassava leaves before storage root bulking. Soluble sugar and starch concentrations were examined over a 24-h cycle (16:8 photoperiod) in CsCMV-infected plants. The expression of an array of genes-carbohydrate metabolism, SnRK1 activity marker, defense, circadian marker-was analyzed at ZT6, ZT16 and ZT24/ZT0. In CsCMV-infected source leaves, at ZT6, sucrose increased whereas glucose, fructose and sucrose rose at night. An increase in Suc:hexose ratio and upregulation of SnRK1 activity marker genes and PR1 transcripts were found in infected leaves, suggesting a combination of altered carbon metabolism and defense response mechanisms against the viral infection. GIGANTEA, a clock-controlled gene, showed a reduced expression in infected leaves at ZT6 and ZT24/ZT0, suggesting a circadian phase shift compared with uninfected control plants. Additionally, starch mobilization transcripts were downregulated at ZT24/ZT0, though starch content remained unchanged during the 24-h cycle. In sink leaves, a transient peak of maltose (ZT6) was observed. Our findings suggest that CsCMV disrupts the plant's natural rhythms of sugar metabolism and allocation. Spikes in sucrose levels may serve as infection signals in the internal daily clock of the plant, influencing plant responses during the cassava-CsCMV interaction.

Protoplasts isolated from Arabidopsis leaves were used to study the initial stages of the plant cell response to osmotic stress. The role of sterols in these processes was investigated by their extraction from the protoplast plasma membrane in the presence of the oligosaccharide - methyl-β-cyclodextrin (MβCD). Depletion of membrane sterols caused by MβCD treatment did not alter protoplast volume under isosmotic conditions; however, volumes changed significantly when protoplasts were exposed to osmotic stress. Estimation of the plasma membrane water permeability coefficient (P_os), calculated from the initial rate of protoplast osmotic shrinkage, showed that control suspension is characterized by a high dispersion of the P_os values. However, P_os became more homogeneous after plasma membrane sterol depletion. Protoplasts were stained with FM 1-43 to assess how sterol extraction affects vesicular transport under osmotic shock. In order to determine the protoplast non-osmotic volume (V_b) steady-state volumes at different external osmolarities were fitted with linear dependences of the Boyle-van't Hoff (BVH) plot. It was found that sterol extraction is accompanied by a change in the slope of the BVH plot and a decrease in the apparent V_b. Several possible mechanisms behind the change in the protoplast volume and plasma membrane P_os regulation by sterols under osmotic stress are discussed.

Biochar and SiO₂ NPs are effective soil conditioners, but the impacts and mechanisms of combined application in oilseed rape are not yet clear. Therefore, an experiment was designed to investigate oilseed rape growth, physiological indexes, and transcriptome sequencing under four treatments: control (CK), Platanus orientalis L. leaf biochar (B), SiO₂ NPs (S), and BS. Our results showed that B, S and BS treatments all promoted the root growth, root activity and biomass of oilseed rape, especially the root length and fresh weight in BS, which were increased by 77.48% and 279.07%, respectively. Moreover, the three-dimensional fluorescence spectra of B and BS were similar, and the tyrosine-like substance proportion in B, S and BS increased from 7.8 to 9.4%, 10.2% and 19.5%, respectively. In transcriptome analysis, there were 10,280 differentially expressed genes (DEGs) shared in B and BS, 3431 DEGs shared in S and BS, and 2815 DEGs shared in B, S and BS. We also found that B, S and BS all regulated oilseed rape growth by inducing the lignin biosynthesis and the relevant genes encoding BBE-like, BGL, UDP in the phenylpropanoid biosynthesis pathway. The results provide gene regulation associated with the phenylpropanoid biosynthesis applying the biochar and SiO₂ NPs, which can be used to increase biomass.

In this study, members of the BvDof transcription factor family were identified in the beet genome data (Beta vulgaris L.) Through systematic analysis, 22 BvDof family genes were found in the beet genome, and they were divided into nine groups by phylogenetic analysis. Fifteen members of the BvERF family were involved in the transition to rapid root tuber growth. There was a tandem replication during the generation of the Dof gene family in sugar beet. Bv1_zfms, Bv_ofna, Bv5_racn, and Bv6_augo may be involved in the regulation of secondary cambium development in the beet root tuber. Bv9_nood, Bv1_zfms, and Bv6_cdca may be related to the growth rate of root tubers. The results provide a reference for further elucidating the molecular mechanism of the BvDof transcription factor, which regulates the development of beet root tubers.

Reproductive interference, an interspecific interaction in reproductive process that exerts an adverse effect, has gained attention as a contributing factor in promoting exclusive distributions between closely related species. However, detailed studies on the possibility of reproductive interference between native plants are still lacking, presumably because strong reproductive interference can rapidly realize exclusive distributions, leaving the two species apparently independent. Salvia japonica and S. lutescens are found in separate localities at a small scale, although their distributions overlap at a large scale. We investigated the possibility of reproductive interference between them through field surveys, hand-pollination experiments, evaluation of hybrid fertility, cpDNA and nrDNA genotyping, and genome-wide DNA analysis. The field survey results did not reveal apparent negative interaction in competition for pollinator services. Mixed pollination with conspecific pollen and counterpart pollen reduced seed set in S. japonica, and hybrid progeny produced by mixed pollination were less than 20% as fertile compared to the pure species. The DNA genotyping results suggested the possibility of hybridization where their distributions overlap, and the genome-wide DNA analysis results showed clear genetic differentiation between the two species as well as the existence of hybrids. These results suggest that bi-directional reproductive interference between S. japonica and S. lutescens may have led to their present separated distributions at a small scale.

Athyrium yokoscense is hypertolerant to cadmium (Cd) and can grow normally under a high Cd concentration despite Cd being a highly toxic heavy metal. To mitigate Cd stress in general plant species, Cd is promptly chelated with a thiol compound and is isolated into vacuoles. Generated active oxygen species (ROS) in the cytoplasm are removed by reduced glutathione. However, we found many differences in the countermeasures in A. yokoscense. Thiol compounds accumulated in the stele of the roots, although a long-term Cd exposure induced Cd accumulation in the aerial parts. Synchrotron radiation-based X-ray fluorescence (SR-XRF) analysis indicated that a large amount of Cd was localized in the cell walls of the roots. Overexpression of AyNramp5a, encoding a representative Fe and Mn transporter of A. yokoscense, increased both Cd uptake and Fe and Mn uptake in rice calli under the Cd exposure conditions. Organic acids are known to play a key role in reducing Cd availability to the plants by forming chelation and preventing its entry in free form into the roots. In A. yokoscense roots, Organic acids were abundantly detected. Investigating the chemical forms of the Cd molecules by X-ray absorption fine structure (XAFS) analysis detected many compounds with Cd-oxygen (Cd-O) binding in A. yokoscense roots, whereas in the aerial parts, the ratio of the compounds with Cd-sulfur (Cd-S) binding was increased. Together, our results imply that the strong Cd tolerance of A. yokoscense is an attribute of the following two mechanisms: Cd-O compound formation in the cell wall is a barrier to reduce Cd uptake into aerial parts. Thiol compounds in the region of root stele are involved in detoxication of Cd by formation of Cd-S compounds.

Hibiscus is a charismatic genus of the Malvaceae family that is noted for its diversity, lacking identifiable characteristics for distinguishing its various species. Therefore, there is an urgent need to develop authentication methods for genus delimitation and species delineation. The present study aims to discern the taxonomic relationships between the well-known, globally familiar, and economically important five Hibiscus species, namely: H. × rosa-sinensis, H. sabdariffa, H. schizopetalus, H. syriacus and H. tiliaceus based on traditional morphological and anatomical characteristics compared to the contemporary chemotaxonomy. In this context, the leaf-based methanolic extracts of the studied species were analyzed by Gas Chromatography-Mass Spectrometer (GC-MS) to estimate their secondary metabolites similarity. In addition, selected qualitative morphological and anatomical traits including leaf venation patterns, epidermal micromorphology, stomata types and trichomes diversity, petiole serial sectioning (outline, adaxial groove features, vasculature traces arrangement), and midrib characteristics of the studied species were investigated. The results of both chemotaxonomy and traditional taxonomy exhibited a remarkable agreement in the delineation of the five studied species. Specifically, the chemotaxonomy-based dendrogram separates the studied species into two main clusters with the H. sabdariffa as an outlier species in a single cluster and the remaining four species as another cluster with variant distances in its similarity indices. Similarly, the traditional morphological and anatomical characteristics revealed distinct traits for H. sabdariffa compared to the remaining four species. The findings of this study highlight the significance of integrating the structural features with phytochemicals profiling as a potential approach that could be harnessed for the delineation of the taxonomically challenging Hibiscus genus.

Cloud forests figure as one of the most diverse ecosystems, accounting not only for a high number of plant species but also with a great variety of interactions among them. A common interaction in these forests is the one between vascular epiphytes and their hosts. However, few studies have used the network approach to analyze them. Here, we analyze the horizontal and vertical structure of the vascular epiphyte - host network in a cloud forest in central Mexico. We quantified the number of epiphyte stands on each host both total and per-stratum. Complete network, group, and species metrics were estimated at both levels of analysis. The host - epiphyte networks had relatively low network size but were highly connected; moderately nested, with low specialization, and modularity; but higher vulnerability than generality, and high niche overlap. The community was composed by a high number of generalist species. To our knowledge this is the first study in which network analyses are conducted with standardized data and including all host and epiphyte species in the community. The analyses suggest that the networks are robust, and that functional redundancy might be probable, two advantageous characteristics in a very fragmented and threatened cloud forest.