Journal of Plant Research最新文献

Palhinhaea cernua, a lycophyte, and Dicranopteris linearis, a fern, are commonly observed in solfatara fields in Kyushu, Japan, but their distribution trends are different. The aim of this study was to determine why P. cernua is more abundant in areas closer to fumaroles from both a soil and plant perspective. Samples of P. cernua and D. linearis, as well as their respective growing soils, were collected, and the mineral properties, including the concentration of various mineral elements and inorganic anions and δ¹⁵N, were determined. P. cernua was better adapted to soil with lower pH, higher soluble aluminum concentrations, and poorer calcium and phosphorus concentrations than D. linearis. A positive correlation was observed between shoot nitrogen concentration and both shoot sulfur concentration and soil water-soluble sulfur concentration in P. cernua, implying the involvement of sulfur in nitrogen acquisition in P. cernua. The results also suggested that D. linearis mainly uses soil NO₃-N, while P. cernua uses NH₄-N, which is predominant and excessive in the solfatara fields, particularly near the fumaroles. This high preference for NH₄-N in P. cernua was confirmed through a cultivation experiment. While D. linearis prefers NO₃-N and distributes further from fumaroles, P. cernua may have survived in the solfatara fields by utilizing NH₄-N and sulfur, which are abundant near fumaroles where competition from other plant species is minimal.

Genetic analysis is important for modern plant molecular biology, and in this regard, the existence of specific mutants is crucial. While genome editing technologies, particularly CRISPR-Cas9, have revolutionized plant molecular biology by enabling precise gene disruption, knockout methods are ineffective for lethal genes, necessitating alternatives like gene knockdown. This study demonstrates the practical generation of a hypomorphic mutant allele, alongside severe null mutant alleles, via the targeting of mRNA splicing sites using CRISPR-Cas9. The Arabidopsis HIGH PLOIDY 2 (HPY2) encodes a yeast NSE2 ortholog, part of the conserved eukaryotic SMC5/6 complex, with SUMO E3 ligase activity essential for cell cycle progression and plant development. Loss-of-function HPY2 mutants exhibit severe dwarfism and seedling lethality, making functional analysis challenging. To overcome these limitations, we created HPY2 knockdown mutants as novel tools to investigate gene function. Of the three mutant alleles, the hpy2-cr1 and hpy2-cr2 mutants resembled the existing severe hpy2-1 allele, both harboring a single base pair insertion in one exon, causing significant root shortening and seedling lethality. In contrast, the hypomorphic mutant hpy2-cr3, which has a five bp deletion at an intron-exon junction, showed relatively longer root growth and survived until the reproductive stage. RT-PCR analysis of hpy2-cr3 revealed atypical mRNAs producing truncated polypeptides that retained some HPY2 function, explaining the milder phenotype. These results establish the successful generation of novel hypomorphic mutant alleles critical for studying the lethal gene HPY2, and demonstrate the usefulness of CRISPR-Cas9 for producing viable hypomorphic mutants for investigating complex genetic interactions.

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.

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.

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.

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.

Salinity and light markedly influence cyanobacterial viability. High salinity disrupts the osmotic balance, while excess light energy affects redox potential in the cells. Regulating the ratio of saturated and unsaturated alka(e)ne and fatty acids in cyanobacteria is thought to have crucial roles in coping with these stresses by regulating membrane fluidity. In Synechococcus elongatus PCC 7942 (Syn7942), alkane is produced from fatty acid metabolites using acyl-acyl carrier protein reductase (Aar) and aldehyde-deformylating oxygenase (Ado) enzymes. However, the role of alka(e)nes and their correlation with fatty acid-related compounds, especially under salinity stress, is not yet fully understood. This study explored the significance of the natural alka(e)ne biosynthesis pathway using Syn7942. The role of alka(e)ne was assessed using single and double knockout mutants of the aar and/or ado genes in this biosynthetic process. The alka(e)ne levels and membrane lipid content exhibited an inverse relationship, correlating with cell fluidity under high-salinity and high-light conditions. The absence of alka(e)ne resulted in a severe growth phenotype of Δado and Δaar/Δado under high-salinity conditions and less severe under high-light conditions. In addition, feeding with C15:0 and/or C17:0 alkanes complemented the growth phenotype with different accumulation profiles. The Δaar mutant exhibited higher resistance to high salinity than the Syn7942 WT, indicating the importance of Ado for survival at high salinity. Overall, lipid-related compounds, especially alka(e)nes, markedly contribute to cell integrity maintenance under high-salinity conditions by regulating membrane rigidity and fluidity.

Breeders adjust wheat heading dates to improve regional adaptability and reduce or mitigate yield losses caused by meteorological disasters, pests and diseases. The Ppd-1 genes play a crucial role in determining wheat sensitivity to changes in day-length and serve as key regulators of heading dates once the vernalization requirement is satisfied. In this study, we identified a new allelic variant of the promoter region, Ppd-B1a.3, in the Chinese wheat cultivar Qingchun 37. Compared to the Ppd-B1b.1 (carried by Chihokukomugi), the main mutation sites in Ppd-B1a.3 include a substitution of C with G at the -505-bp, a T base insertion at the -625-bp, a mutation of TCG to GGT at the -632 to -634-bp, and a 163-bp insertion at the -691 bp. Analysis of F₂ populations indicated that Ppd-B1a.3 promotes heading and flowering (approximately 6 days earlier in population 1 and 17 days in population 2) under short-day conditions in a greenhouse. However, the evaluation of Ppd-B1a.3's effect under field conditions may be influenced by the copy number of the Ppd-B1 locus inherited from the other parent in the F₂ populations. Ppd-B1a.3 disrupts circadian rhythm expression and exhibits a stronger effect on heading and flowering than the three-copy Ppd-B1 allele carried by Jing 411. Origin analysis suggests that Ppd-B1a.3 may have derived from non-native germplasm. These results deepen our understanding of wheat photoperiod genes and provide useful genetic resources for fine-tuning wheat heading dates during breeding.