Functional Plant Biology最新文献

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.

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 .

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.

Macadamias (Macadamia spp.) are highly desired for their flavour and nutritional characteristics. Despite cultivation in their native habitat, unpredictable and extreme weather events are applying pressure on the Australian macadamia industry to maintain the production of high-quality kernels. The industry has experienced losses in yield and quality due to shifts in the timing and volume of rain in recent years, and this has identified the requirement for transformational changes in orchard agronomic practices. Pre-harvest conditions that impinge on kernel oil content, kernel recovery, whole kernels and kernel appearance are discussed in this review. The impact of harvest and storage conditions on kernel quality are also reviewed. We propose opportunities for further research to optimise on-farm practices and to safeguard kernel quality post-harvest. This includes building on existing research to advance our understanding of the interaction of genetics with plant response to climate change. It also requires innovation to advance technologies that foster precision management, both spatially and temporally, in an environmentally sensitive manner.

Wheat undergoes significant physiological changes during winter, driven by processes such as cold acclimation and vernalisation that are regulated by gene expression and phytohormones. We investigate the effects of methyl jasmonate (MeJA) and cold treatments on the expression of three specific miRNAs and the associated target genes in Baz spring wheat and Norstar winter wheat using qRT-PCR analysis. Our objective was to examine the impact of MeJA on vernalisation and cold adaptation in these genotypes. Results showed that MeJA had no significant impact on vernalisation and acclimation in Baz, while the compound decreased these traits in Norstar. Additionally, the expression of miRNAs in Norstar was significantly reduced after a 2-day cold treatment, particularly for miR156 and further reduced after 14days for miR172 and miR319 . In contrast, Baz showed varied gene expression responses, with an increase in miRNA levels after the 14-day cold treatment. MeJA combined with a 2-day cold treatment suppressed the expression of SPL , AP2 and MYB3 target genes, with the most pronounced suppression observed in SPL . However, AP2 was induced after 14-day cold treatment in both cultivars. The study highlighted an inverse relationship between miRNAs and target genes under vernalisation conditions, underscoring the complex regulatory interactions between genotype, miRNAs and the associated target genes. Therefore, these findings provide new insights into how MeJA and cold treatments modulate miRNA and gene expression, enhancing our understanding of wheat's adaptive response mechanisms.

The nuclear factor-Y (NF-Y) transcription factor, also known as heme-activator protein (HAP) or CCAAT-binding factor (CBF), is a critical transcription factor widely present in eukaryotes. The number of NF-Y subunits has significantly increased in higher plants compared to animals and fungi. The NF-Y complex is composed of three subunits: (1) NF-YA; (2) NF-YB; and (3) NF-YC. NF-YB and NF-YC contain histone fold domains (HFDs), which can interact with NF-YA or other transcription factors, or directly bind to the promoter CCAAT box to regulate the transcription of downstream genes. NF-Y plays a significant role in various plant processes, including growth and development. This review elucidates the structural and functional aspects of NF-Y subunits, identified NF-Y complexes, and their molecular regulatory mechanisms. Understanding these facets of NF-Y provides valuable insights into advancing crop genetic improvement and promoting sustainable agricultural practices.

The biochemical and transcriptional regulatory mechanisms of chlorophyll metabolism have been extensively studied, but the translational regulatory mechanisms remain poorly understood. In this study, we found that Nt DHS1 deficiency in N. tabacum resulted in smaller leaves and increased leaf chlorophyll content. Protein content determination experiments revealed that the global protein synthesis of the Ntdhs1 mutant was decreased. A ribosome profiling sequence (Ribo-seq) assay showed that the translation level of genes related to cell growth was significantly reduced, while the translation level of chlorophyll metabolism related genes was significantly increased in Ntdhs1 mutant. Biochemical analysis further demonstrated that Nt DHS interacts with the translation initiation factor Nt eIF5A. Moreover, the Nteif5a1 mutant exhibited phenotypes similar to the Ntdhs1 mutant, including a reduced translation level of cell growth related genes and increased translation level of chlorophyll metabolism related genes. Our studies suggest that the Nt DHS-Nt eIF5A complex regulates leaf senescence by modulating the translation of specific genes.

Oxalate druse synthesis in plants helps to reduce drought stress by maintaining osmotic balance and might also act as a defence against herbivory by reducing nutritional quality. This study experimentally investigated the role of druses in Atriplex lampa under drought and herbivory treatments. We propose that both stressors trigger druse synthesis. Furthermore, if druse production is an adaptation to stress, the allocation of resources to other physiological functions should not be affected. These hypotheses were experimentally tested under greenhouse and natural field conditions. Leaves of A. lampa were collected from eight rangelands in Monte Desert in Argentina, which shared similar environmental characteristics but differed in stocking rates. The manipulative experiment in the greenhouse consisted in applying drought and herbivory treatments to A. lampa seedlings. The highest druse abundance was observed at intermediate stocking rates, suggesting resource limitation for druse synthesis at extreme stocking rates. The adaptive advantage of druse synthesis was evident only for drought stress treatment, where higher druse abundance was correlated with improved growth rates. When both stressors were combined, there was no difference in druse abundance with respect to control treatment, indicating that herbivory negatively influenced the adaptive response to drought. Druse synthesis is an adaptation to drought that is susceptible to herbivory stress.

Non-photochemical quenching and limitations of the photosystem I and photosystem II activities were studied in C3 -plant barley and C4 -plant maize. Plants were exposed to prolonged heat stress under high and low air humidity. Both species decreased non-photochemical quenching at 37-42°C, which increased at 46°C. A decrease of photosystem II activity at 46°C in lower air humidity was achieved through different mechanisms. In barley, photosystem II was downregulated by the increase of non-photochemical quenching. In maize, photosystem II was downregulated by the increase of acceptor-side limitation. Analysis of transients also revealed differences between species. One second after a light induction, limitations flashes at the acceptor sides of both photosystems. Elevating the temperature decreased these flashes; acceptor-side limitations of both photosystems decreased proportional to each other. In maize, the size of flashes slightly diminished at 37°C and decreased more at 42-46°C. In barley, the size of flashes greatly decreased at 37°C and gradually returned to the control level under higher temperatures. Around photosystem II, the flash was quenched by a burst of non-photochemical quenching. In barley, the transient peaks of acceptor-side limitation and non-photochemical quenching were very similar at any temperature. This was not observed in maize.

Use of fossil fuels causes environmental issues due to its inefficiency and and imminent depletion. This has led to interest in identifying alternative and renewable energy sources such as biofuel generation from photosynthetic organisms. A wide variety of prokaryotic and eukaryotic microorganisms, known as microalgae, have the potential to be economical and ecologically sustainable in the manufacture of biofuels such as bio-hydrogen, biodiesel, bio-oils, and bio-syngas. By using contemporary bioengineering techniques, the innate potential of algae to produce biomass of superior quality may be enhanced. In algal biotechnology, directed genome modification via RNA-guided endonucleases is a new approach. CRISPR/Cas systems have recently been frequently used to modify the genetic makeup of several aquatic and freshwater microalgae. The majority of research has used the Cas9-driven Type II system, one of two classes and six unique kinds of CRISPR systems, to specifically target desired genes in algae, and knock them out and down, or both. Using CRISPR technology to modify its genetic makeup, microalgae has produced more biomass and increased in lipid content. This review highlights the attempts made so far to target microalgae genome modification, discusses the prospects for developing the CRISPR platform for large-scale genome modification of microalgae, and identifies the opportunities and challenges in the development and distribution of CRISPR/Cas9 components.