Functional Plant Biology最新文献

The phytochrome (phy) photoreceptors, comprising a small family of species, regulate plant development, being most active under red (R) and far-red (FR) light. One of the major phytochromes, phyA, is unique among the others: it mediates distinct photoreactions - the very low fluence responses (VLFR), the high irradiance responses (HIR), and the low fluence responses (LFR) characteristic of phyB. This functional diversity is likely to be connected with its heterogeneity: there are two native pools, possibly differing by serine phosphorylation at the N-terminus - phyA' mediating the VLFR and phyA″ responsible for the HIR and LFR. In this work, we investigated their nature by in vivo spectrofluorimetry, turning to the chlorophyll-less albino barley mutant. It was characterized both by the higher total phyA content and the proportion of phyA' in etiolated coleoptile tips. The lack of protochlorophyllide (PChlide) allowed characterization of phyA pools in primary leaves (of the mutant) - the phyA'/phyA″ proportion was the same as in the coleoptiles, whereas their content was substantially lower. phyA' in the mutant coleoptiles revealed less lability under light as compared with the wild type, suggesting that the mutation may affect the phyA's proteolytic system. A specific effect of FR light on phyA in coleoptiles was observed - a relatively fast (tens of minutes) conversion of phyA' into phyA″ that may be part of the complex process of plant light adaptation.

While the effects of plant growth-promoting rhizobacterium, Azospirillum , on abiotic stress tolerance in plants are widely reported, the mechanisms that underlie this process remain elusive. Surface lectins of strains A. brasilense Sp7 and A. baldaniorum Sp245 are capable of attaching to specific carbohydrates and ensure the binding of bacteria to the surface of the plant root. They exhibit multifunctionality, and the effects induced by lectins are dose-dependent. This work investigated mechanisms by which lectins improved drought tolerance in wheat (Triticum aestivum ) plants. In the roots of wheat seedlings under drought stress, lectins with varying intensities increased the activity of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). Lectins caused a decrease in lipid peroxidation, but increased the content of secondary metabolites such as total phenolics and flavonoids. In the roots of stressed seedlings, lectins increased the total protein content and caused a dose-dependent change in the electrophoretic spectra of low molecular weight proteins. It was concluded that Azospirillum lectins, due to their ability to influence the metabolism of the host plant, are involved in adaptive changes in the roots of wheat seedlings. Lectins can regulate the relationship between bacteria and their hosts when soil and climatic factors change.

Shading plays an important role in determining nutrient content and yield fo wheat (Triticum aestivum ). However, the genetic mechanism underlying the effects of shading treatment on grain filling remains unclear. Therefore, we performed phenotypic and transcriptome analyses on wheat cv. ZY96-3 during grain development under normal and shaded conditions. Shading resulted in a significant decrease in grain size and 1000-grain weight. Correlation analysis revealed the strong effect of shading on the mean and maximum grain-filling rate and secondary grain-filling parameters R 2 and R 3 . And shading reduced starch content and starch-related enzyme activity (including granule-bound starch synthase and soluble starch synthase). Transcriptomic analyses showed that shading mainly affected pathways related to photosynthetic antenna proteins, carbon fixation in photosynthetic organisms, and starch and sucrose metabolism. Sixteen genes related to photosynthetic antenna protein and carbon fixation pathways were first upregulated and then downregulated; whereas all differentially expressed genes (PetC , Fd , LFNR1 , LFNR2 , PC , PsbO , PsaG , and PSB28 ) in the photosynthetic antenna protein pathway belonged to electron transport chain proteins. We found that shading treatment affects the physiological and molecular properties of grain development during the grain-filling stage. This study reveals new candidate genes (such as TaLFNR1-7A and TaFd-7A ) for breeding wheat varieties with high photosynthetic efficiency in regions with insufficient light intensity.

Fatty acid desaturases (FADs) represent a class of oxygen-dependent enzymes that dehydrogenate C-C bonds in fatty acids (FAs) producing unsaturated C=C bonds that markedly change the properties of lipid membranes, which is critical for protein and lipid diffusion, perception and transduction of environmental signals, cell division, etc . Membrane-located FADs (acyl-lipid FADs of plants and bacteria, as well as animal acyl-coenzyme A (CoA) FADs) are highly conserved from viruses to human. These enzymes are highly specific towards their acyl substrates, as well as towards the position and geometric configuration of the newly introduced cis double bonds. The regiospecificity of soluble Acyl-Carrier-Protein (ACP) Δ9-FADs was determined relative to the carboxyl end of the FA. Similar regiospecificity was suggested for acyl-lipid and acyl-CoA FADs Δ9-FADs. It was previously thought that acyl-lipid Δ12-FADs (also known as ω6-FADs) also count from the carboxyl terminus of an FA. However, heterologous expression and supplementation of model yeast or cyanobacterial strains with exogenous monounsaturated odd- and even-chain FAs revealed that plant and cyanobacterial acyl-lipid Δ12-FADs use neither end of the FA (Δ or ω) as a counting reference point; but count three carbons toward the methyl end from an existing double bond in the monoene precursors irrespective of FA chain length. Δ6-FADs appeared to 'count' from the carboxyl terminus. ω3-FADs that contribute to unsaturation of C16-C18 FAs of membrane lipids, in fact, are Δ15-FADs that also 'count' from the C-terminus of acyl chains. The exact knowledge of counting order is crucial for understanding the modes of FADs activities and for further construction of biochemical pathways for biosynthesis of polyunsaturated FAs.

The dependence of agriculture on water availability is an important premise justifying attempts to enhance water use efficiency for plant production. Photosynthetic efficiency, directly impacts biomass production, is dependent on both water availability and the quality and quantity of light. Understanding how these factors interact is crucial for improving crop yields. Many overlapping signalling pathways and functions of common bioactive molecules that shape plant responses to both water deficit and light have been identified and discussed in this review. Separate or combined action of these environmental factors include the generation of reactive oxygen species, biosynthesis of abscisic acid, stomatal functioning, chloroplast movement and alterations in the levels of photosynthetic pigments and bioactive molecules. Plant response to water deficit depends on light intensity and its characteristics, with differentiated impacts from UV, blue, and red light bands determining the strength and synergistic or antagonistic nature of interactions. Despite its significance, the combined effects of these environmental factors remain insufficiently explored. The findings highlight the potential for optimising horticultural production through controlled light conditions and regulated deficit irrigation. Future research should assess light and water manipulation strategies to enhance resource efficiency and crop nutritional value.

Catharanthus roseus has various terpenoid indole alkaloids (TIAs) with adaptive mechanisms to withstand both biotic and abiotic stresses. We investigated the effects of methyl jasmonate (MeJA) on alternative splicing (AS) mechanisms in C. roseus to identify differentially expressed alternatively spliced (DAS) genes following MeJA treatment. We found pairs of co-expressed splicing factors (SFs) and DAS genes and potential roles of co-expressed SFs in the maturation of their respective transcripts. Twenty two clusters encompassing 17 MeJA-responsive DAS genes co-expressed with 10 SF genes. DAS genes, C3H62 , WRK41 , PIL57 , NIP21 , and EDL6 , exhibited co-expression with the SF genes SR34a , DEAD29 , SRC33 , DEAH10 , and DEAD29 , respectively. These gene pairs are implicated in plant developmental processes and/or stress responses. We suggest that MeJA activates the expression of genes encoding SFs that are regulated in tandem with their co-expressed DAS genes and MeJA may enhance the regulatory frameworks that control splicing mechanisms, resulting in the generation of specific mRNA isoforms. This triggers the expression of particular DAS gene variants to allow the plant to effectively respond to environmental stimuli and developmental signals. Our study advances our understanding on how MeJA modulates alternative splicing in C. roseus , potentially influencing various aspects of plant physiology and metabolism. It is recommended that future studies focus on validating the functional relationships between the identified SF/DAS gene pairs and their specific roles in plant development and stress responses, and exploring the potential of manipulating these splicing mechanisms to enhance the production of valuable TIAs in C. roseus .

The grassland in north-east China has an important ecological service function. However, freeze-thaw, alkaline salt, and Solanum rostratum Dunal often have adverse effects on the stability of grassland ecosystem in this region. In this study, the effects of combined stress of freeze-thaw, alkaline salt, and S. rostratum extract on rye (Secale cereale ) were discussed. It was found that the combined stress of alkaline salt and S. rostratum extract (AR) inhibited the seed germination and seedling growth of rye. Compared with AR in the non-freeze-thaw group, the contents of soluble protein (SP), malondialdehyde (MDA) and hydrogen peroxide (H2 O2 ) of rye seedlings were significantly increased under the combined stress of freeze-thaw, alkaline salt, and S. rostratum extract (FAR), and the activities of superoxide dismutase (SOD) and peroxidase (POD) were significantly increased. Photosynthetic indices (Tr, Pn, gs , Ci) were significantly decreased. The results indicated that freeze-thaw could aggravate the adverse effects of AR treatment on rye seedlings. Therefore, in the period of frequent freeze-thaw, it is important to carry out timely targeted control measures for S. rostratum to reduce the adverse effects of combined stress on grassland ecosystem, which is conducive to the ecological security and stability maintenance of grassland ecosystem in north-east China.

Sorghum (Sorghum bicolor [L.] Moench) is an important forage crop that contains the cyanogenic glucoside dhurrin that releases hydrogen cyanide when tissue is damaged. The acyanogenic (dhurrin-free) sorghum line tcd1 was developed to eliminate the risk of cyanide poisoning from sorghum forage. However, dhurrin may also play a role in nitrogen accumulation and storage. We tested whether dhurrin offers the cyanogenic sorghum line BTx623 a growth advantage relative to tcd1 , when nitrogen is limiting and variable. BTx623 and tcd1 were grown under two 42-day nitrogen treatments: high dose, low frequency ('surge') and low dose, high frequency ('pulse'). BTx623 exhibited no growth advantage or disadvantage compared to tcd1 under either treatment. Young BTx623 plants had high concentrations of dhurrin for defence but rapidly recycled this during nitrogen deficiency under the surge treatment, demonstrating dhurrin's role in both defence and nitrogen storage. At later stages, surge plants appeared to accumulate influxes of nitrogen in nitrate and amino acids but not dhurrin. There was evidence of gene expression promoting increased biosynthesis and reduced recycling of dhurrin following surge nitrogen applications but not pulse applications. These results deepen our understanding of dhurrin's role in nitrogen metabolism and demonstrate tcd1 's potential as a safe forage.

Polytrichum commune exhibits distinct green and yellow-green colouration in shaded and sunny environments, respectively. This study investigates the physiological adaptations underlying this colour shift, focusing on pigment composition and photoprotection. Chlorophyll and carotenoid concentrations, carotenoid:chlorophyll ratios (CAR/CHL), electron transport rates (ETR), and non-photochemical quenching (NPQ) were analysed in samples collected from shaded and sunny conditions, along with a shade-to-sun experiment. Results revealed higher CAR/CHL ratios in sunny samples, facilitating enhanced NPQ and photoprotection. Changing light conditions of the moss from shade to sun increased CAR/CHL (by 1.2 times) and NPQ (by 2.2 times), while reducing chlorophyll and carotenoid levels. These physiological changes correlated with the observed colour shift to yellow-green. The study confirmed that light intensity, not temperature or humidity, drives this response. Additionally, the lamellae structure of P. commune leaves supports efficient gas exchange and photosynthesis under varying light conditions. These findings highlight the adaptive strategies of bryophytes to environmental stress, enhancing our understanding of plant resilience mechanisms. Insights from this research may contribute to broader ecological and physiological studies on light adaptations in plants.

Soil salinity affects plant growth and crop yield. This warrants the urgent need for sustainable management. Our research aims to assess the impact of hydrogel, biochar and biofertilizer on wheat physiology, yield, soil nutrients and enzymes. The study was carried out at the dry bed of the Aral Sea. The experimental design included hydrogel, biochar, biofertilizer (Yer malxami includes Azotobacter chroococcum, Pseudomonas putida and Bacillus subtilis ) and control treatments. After 60days of sowing, plant growth metrics, physiological qualities, root morphological features, soil nutrients and enzyme activities were measured. The findings revealed significant improvement in growth of wheat following biofertilizer, hydrogel and biochar treatments. Applying biofertilizer resulted in a notable increase in the total root length by 69.9%, root volume by 123.7% and root diameter by 84.6%, and the highest chlorophyll a (Chl a ) by 13.3%, chlorophyll b by 13.7% (Chl b ) and total chlorophyll content by 13.1% compared to other treatments. Biofertilizer treatment significantly enhanced plant nitrogen (N) content by 16.0%, phosphorus (P) content by 94.7% and potassium (K) content by 51.8%, and increased the activities of soil enzymes such as catalase and invertase. The implementation of these soil amendments can be posited to mitigate the deleterious effects of saline conditions on wheat and can improve wheat growth under salinity stress.