Physiologia plantarum最新文献

Photorespiration is an essential metabolic repair process in oxygenic photosynthesis, as it detoxifies Rubisco's inhibitory oxygenase byproduct, 2-phosphoglycolate (2-PG). It has been demonstrated that improving endogenous photorespiration in C3 plants through enzyme overexpression can enhance photosynthesis and promote plant growth. However, the potential impact of improved photorespiration in leaves on heterotrophic roots remained unexplored. To address this, we conducted a metabolome analysis of Arabidopsis leaves and roots using transgenic lines with enhanced glycine decarboxylase (GDC) activity, achieved by overexpressing the mitochondrial lipoamide dehydrogenase (mtLPD1) subunit. In the leaves, mtLPD1 overexpression primarily resulted in reduced steady-state levels of intermediates associated with photorespiration, the tricarboxylic acid (TCA) cycle, and soluble sugars, while intermediates related to nitrogen metabolism were elevated. In roots, where mtLPD1 expression was unchanged, we observed contrasting accumulation patterns in the transgenic lines compared to the wildtype, including increased levels of photorespiratory and TCA-cycle intermediates. Notably, we also detected elevated amounts of soluble sugars, nitrate, and starch. Phloem exudate analysis revealed altered metabolite profiles in the overexpressors, particularly with respect to photorespiratory intermediates linked to the GDC reaction, as well as soluble sugars and metabolites involved in cellular redox homeostasis. This suggested an increased transport of these metabolites from shoots to roots, thereby altering sink organ metabolism. In summary, we hypothesize that optimizing photorespiration enhances photosynthesis, which leads to an increased export of carbon surplus to heterotrophic tissues. Thus, improving photorespiration may hold potential for increasing yields in beet- and tuber-forming plants.

Black and red rice are known for their rich nutritional content, yet most varieties suffer from a firm texture and insufficient fragrance. In this study, we aimed to develop a fragrant and soft-textured black and red rice variety using the CRISPR/Cas9 technology to knock out the OsWx gene, which is associated with amylose content (AC), and the OsBADH2 gene, responsible for rice aroma. Our results showed that, compared to wild-type, CRISPR lines of XHZ, HM, NWZ, and PGZ targeting OsWx and OsBADH2 exhibited a reduction in AC content, altered gel consistency, and a more than 50% increase in gel consistency. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis revealed that the 2-acetyl-1-pyrroline (2-AP) content in the grains of xhz-c^{BADH2 Wx} and hm-c^{BADH2 Wx} reached 189.04 μg kg^-1 and 309.03 μg kg^-1, respectively. Furthermore, we observed a slight increase in anthocyanins and proanthocyanidins in these co-edited lines, without significant effects on their agronomic traits. Furthermore, to investigate the genes involved in the quality formation of black and red rice for the knockout of OsBADH2 and OsWx, we conducted RNA-seq analysis. The results indicated that knockout of OsBADH2 and OsWx affected the expression of genes involved in carotenoid biosynthesis, multiple amino acid metabolism genes, and endosperm starch and sucrose metabolic pathways. These findings suggest that the CRISPR/Cas9 technology can effectively target OsBADH2 and OsWx to develop high-quality black and red rice varieties with enhanced aroma and softer texture, providing a new strategy for the improvement of colored rice.

The plant hormone auxin (Indole-3-Acetic Acid, IAA) is a key player in nearly every aspect of plant growth and development ranging from cell division and cell elongation to embryogenesis and root formation. The IAA level in specific tissues and cells is regulated by synthesis, conjugation, degradation and transport. Especially long-range polar auxin transport (PAT) has been the subject of numerous studies. The chemi-osmotic theory predicts that intercellular PAT is caused by an asymmetric distribution of auxin efflux transporters in cell membranes of transporting cells, resulting in increased local membrane permeability for IAA. Members of the PIN gene family are generally considered to encode the postulated carriers. The objective of this study was to use the chemi-osmotic theory in an experimental program aimed at describing and interpreting long-range PAT data from mutants of the PIN gene family of Arabidopsis thaliana. Therefore, we put the chemi-osmotic theory in a broader theoretical framework. We find that the observed decrease in both auxin flux and transport velocity in pin1 loss-of-function mutants is not caused by decreased basal membrane permeability, as would be expected according to the chemi-osmotic theory, but is an indirect effect caused by a change in the dynamics of auxin transport due to a decrease in the expression of all four AUX1/LAX1-3 auxin influx carriers in pin1 mutants. On the basis of our findings, we conclude that the exact role of PIN1 in long-distance PAT, as postulated in the chemi-osmotic theory, should be reconsidered.

Powdery mildew (PM) caused by Eeysiphe heraclei is a serious concern in Heracleum moellendorffii Hance. E. heraclei is a biotrophic fungus that absorbs glucose as the major carbon energy source, using haustoria after infection. However, the mechanisms of sugar efflux from host cells to the fungus remain undetermined. Our previous study revealed that E. heraclei infection altered sugar transfer and distribution in H. moellendorffii, and that increased sugar concentrated in the infected regions. Here, RNA-sequencing was used to identify a key sugar transporter, HmSWEET1, which transported hexose sugars. Overexpression or silencing of the HmSWEET1 gene in H. moellendorffii enhanced or reduced resistance to PM by regulating sugar concentrations in infection sites. Further analysis identified two key transcription factors, HmERF1 and HmbZIP1, which are bound to the HmSWEET1 promoter, inhibit the gene expression. Furthermore, overexpression of HmERF1 and HmbZIP1 in H. moellendorffii enhanced plant resistance to PM by interfering with the ability of HmSWEET1 to transport sugars, thereby decreasing the sugar concentrations in infected leaf areas. Moreover, HmERF1 interaction with HmbZIP1 in H. moellendorffii further enhanced plant resistance. The results identified a novel HmERF1-HmbZIP1-HmSWEET1 module, which strengthened PM' resistance by reducing sugar supplies in H. moellendorffii through suppression of sugar transport by HmSWEET1.

Cysteine plays a crucial role in various processes throughout plant growth and development stages. The gene OASA1 can produce cysteine in Arabidopsis. However, the potential developmental roles of OASA1 have not been explored during senescence. In the present study, the gene OASA1 showed increasing expression during senescence. Compared with Col-0, the mutant oasa1-1 and oasa1-2 showed late leaf senescence, which may be due to disturbed cysteine homeostasis. The mutant exhibited lower total cysteine content and reduced chlorophyll degradation. Meanwhile, WRKY75 promotes cysteine production by inducing the transcription of OASA1 expression, affecting leaf senescence. Our results demonstrate that the senescence-responsive transcription factor WRKY75 directly activates the expression of OASA1 to promote cysteine accumulation and H₂O₂ content, suggesting a mechanism by which senescence regulates cysteine accumulation in plants.

DNA damage caused by internal and external stresses negatively affects plant growth and development. In this, DNA repair enzymes play an important role in recognizing and repairing the caused DNA damage. The first key enzymes in the base excision repair (BER) pathway are DNA glycosylases. In this paper, we present updated knowledge on the classification, phylogeny and conserved structural domains of DNA glycosylases in the plant base excision repair pathway. It describes the key roles played by the DNA glycosylases in plant stress responses, and focuses on the molecular mechanisms of plant stress tolerance from the perspective of the DNA repair system. New opportunities for the development of plant-derived DNA repair genes and DNA repair enzyme resources are discussed.

The xenic strain Chlorella sorokiniana was grown together with selected fungal strains to investigate the effect of fungi on the algal photosynthetic performance during cultivation. The introduction of well-selected fungal strains can potentially increase algal cultivation efficiency. The bacteria that inhabited the algae were identified and the coexistence of the fungi with the algae and bacteria in liquid and solid media was examined. Chlorophyll a fluorescence measurement, a commonly used method for determining the efficiency of plant photosynthesis under stressful conditions, was used to assess the condition of the algae. The algae were cultivated for eight weeks without supplementing the nutrient solution. The experiments showed that the fungal strains Clonostachys rosea, Rhodotorula mucilaginosa and Mortierella alpina formed stable interactions with the microalga C. sorokiniana and the bacteria in the microalgal culture. The time of the measurement and treatments caused changes in the fluorescence curve patterns. Differences in the profiles of the curves in different phases revealed modifications in the operation of the light-dependent photochemical reactions. Generally, the most positive changes in the chlorophyll a fluorescence induction curves (OJIP) were recorded in the double inoculation of C. sorokiniana with R. mucilaginosa + M. alpina and R. mucilaginosa + C. rosea. The results show that selected combinations of fungal strains can be a tool to improve the photosynthetic efficiency of C. sorokiniana.

Pathogenesis-related (PR) proteins are critical defense signaling molecules induced by phytopathogens. They play a vital role in plant's defense signaling pathways and innate immunity, particularly in systemic acquired resistance (SAR) and serve as key molecular markers of plant defense. Overexpressing PR genes, such as chitinase, thaumatin, glucanase, thionin and defensin, either individually or in combination, have significantly boosted plants' defense responses against various pathogens. However, signaling pathways regulating the expression of these versatile proteins remain only partially understood. Plant hormones like salicylic acid (SA) and jasmonic acid (JA) are known for their well-established roles in regulating PR gene responses to pathogens and other stress conditions. PR genes interact with various components of hormonal signaling pathways, including receptors (e.g., NPR1 in SA signaling), transcription factors (e.g., MYC2 in JA signaling), and cis-regulating elements (e.g., W-box), to modulate plant defense responses. Recent studies have highlighted the contributions of different plant hormones to plant immunity and their interactions with PR proteins in a process known as hormonal crosstalk, which helps coordinate immunity activation. This review provides a comprehensive overview of the PR proteins, their complexity, and hormonal crosstalk in immunity, aiming to understand these interactions for improved pathogen resistance.

The huge diversity of cultivated tomatoes is the result of a long process of domestication followed by intensive breeding. Breeding efforts have been focused on increasing fruit size and on the diversification of fruit phenotypes. The formation of seedless (parthenocarpic) fruits in tomato plants is an interesting trait for growers, providing a mechanism to overcome fertilization failure under unfavourable environmental conditions. Early anther or pollen ablation is an effective strategy to promote parthenocarpy in tomato plants and was proven to be effective in several tomato cultivars. Whether this is an ancestral trait or was acquired during domestication and breeding is unknown. In this study, we evaluated the formation of parthenocarpic fruits in the cultivated tomato and the wild relative Solanum pimpinellifolium through the generation of male-sterile mutants. Only cultivated tomatoes, but not Solanum pimpinellifolium plants, produced seedless fruits. Expression analyses showed that parthenocarpy correlates with the activation of fertilization-independent gibberellin biosynthesis in the ovaries. When compared with wild relatives, modern tomato cultivars present small deletions in the promoter of these genes that could account for the differences in gene expression that ultimately trigger parthenocarpy. Our results suggest that seedless fruit production was actively repressed in the absence of pollination in the ancestral tomato lineages.