Plant, Cell & Environment最新文献

Most terrestrial plants can establish a reciprocal symbiosis with arbuscular mycorrhizal (AM) fungi to cope with adverse environmental stresses. The development of AM symbiosis is energetically costly and needs to be dynamically controlled by plants to maintain the association at mutual beneficial levels. Multiple components involved in the autoregulation of mycorrhiza (AOM) have been recently identified from several plant species; however, the mechanisms underlying the feedback regulation of AM symbiosis remain largely unknown. Here, we report that AM colonization promotes the flavonol biosynthesis pathway in tomato (Solanum lycopersicum), and an AM-specific UDP-glucosyltransferase SlUGT132, which probably has the flavonol glycosylation activity, negatively regulates AM development. SlUGT132 was predominantly expressed in the arbuscule-containing cells, and its knockout or knockdown mutants showed increased soluble sugar content, root colonization level and arbuscule formation. Conversely, overexpression of SlUGT132 resulted in declined soluble sugar content and mycorrhization degree. Metabolomic assay revealed decreased contents of astragalin, tiliroside and cynaroside in slugt132 mycorrhizal roots, but increased accumulation of these flavonoid glycosides in SlUGT132-overexpressing plant roots. Our results highlight the presence of a novel, SlUGT132-mediated AOM mechanism, which enable plants to flexibly control the accumulation of soluble sugars and flavonoid glycosides in mycorrhizal roots and modulate colonization levels.

Catharanthus roseus is a highly relevant model for investigating plant defense mechanisms and the biosynthesis of therapeutically valuable compounds, including terpenoid indole alkaloids (TIAs). It has been demonstrated that beneficial microbial interactions can regulate TIA biosynthesis in C. roseus, highlighting the need to fully comprehend the molecular mechanisms involved to efficiently implement eco-friendly strategies. This study explores the effects of a novel microbial strain, Y503, identified as Sphingomonas sp., on TIA production and the underlying mechanisms in C. roseus. Through bioinformatics analysis, we have identified 17 MAPKKKs, 7 MAPKKs, and 13 MAPKs within the C. roseus genome. Further investigation has verified the presence of the MAPK module (CrMAPKKK1-CrMAPKK1/CrMAPKK2-CrMPK3) mediating Y503 in regulating TIA biosynthesis in C. roseus. This study provides foundational information for strengthening the plant defense system in C. roseus through advantageous microbial interactions, which could contribute to the sustainable cultivation of medicinal plants such as C. roseus.

Pandemics originating from zoonotic viruses have posed significant threats to human health and agriculture. Recent discoveries have revealed that wild-rice plants also harbour viral pathogens capable of severely impacting rice production, a cornerstone food crop. In this study, we conducted virome analysis on ~1000 wild-rice individual colonies and discovered a novel single-strand positive-sense RNA virus prevalent in these plants. Through comprehensive genomic characterization and comparative sequence analysis, this virus was classified as a new species in the genus Polerovirus, designated Rice less tiller virus (RLTV). Our investigations elucidated that RLTV could be transmitted from wild rice to cultivated rice via a specific insect vector, the aphid Rhopalosiphum padi, causing less tiller disease symptoms in rice plants. We generated an infectious cDNA clone for RLTV and demonstrated systemic infection of rice cultivars and induction of severe disease symptoms following mechanical inoculation or stable genetic transformation. We further illustrated transmission of RLTV from stable transgenic lines to healthy rice plants by the aphid vector, leading to the development of disease symptoms. Notably, our database searches showed that RLTV and another polerovirus isolated from a wild plant species are widely circulating not only in wild rice but also cultivated rice around the world. Our findings provide strong evidence for a wild plant origin for rice viruses and underscore the imminent threat posed by aphid-transmitted rice Polerovirus to rice cultivar.

The phospholipase Ds (PLDs) are crucial for cellular signalling and play roles in plant abiotic stress response. In this study, we identified 12 PLD genes from the genome data of perennial ryegrass (Lolium perenne), which is widely used as forage and turfgrass. Among them, LpPLDδ3 was significantly repressed by ABA treatment, and induced by drought stress and heat stress treatments. The ectopic overexpression (OE) of LpPLDδ3 in Arabidopsis enhanced plant tolerance to osmotic and heat stress as demonstrated by an increased survival rate and reduced malondialdehyde (MDA) accumulation and electrolyte leakage (EL). Arabidopsis endogenous ABA RESPONSIVE ELEMENT BINDING FACTORs (ABFs) and heat stress responsive genes were elevated in LpPLDδ3 OE lines under osmotic and heat stress treatments. Additionally, overexpression of LpPLDδ3 in perennial ryegrass protoplasts could increase heat stress tolerance and elevate expression level of heat stress responsive genes. Moreover, LpABF2 and LpABF4 depressed the LpPLDδ3 expression by directly binding to its ABRE core-binding motif of promoter region. In summary, LpPLDδ3 was repressed by LpABF2 and LpABF4 and positively involved in perennial ryegrass osmotic and heat stress responses.

The underlying assembly processes of surface microbial communities are crucial for host plants and ecosystem functions. However, the relative importance of stochastic and deterministic processes in shaping epiphytic microbes remains poorly understood in both the phyllosphere and rhizosphere. Here, we compared the spatial variations in epiphytic microbial communities of two dominant grasses along a 1400 km transect on the Tibetan Plateau and assessed the assembly processes between the phyllosphere and rhizosphere. We found significant variations in epiphytic microbial community compositions between plant compartments and host species. Stochastic processes (drift and homogenizing dispersal) predominantly shaped microbial communities in both the phyllosphere and rhizosphere, with a greater contribution of stochastic processes in the phyllosphere. As environmental heterogeneity intensified, we found a transition from stochasticity to determinism in affecting the microbial assembly. This transition to homogeneous or variable selection depended on plant compartments and host species. Our study is among the first to compare the contribution of stochastic versus deterministic processes to epiphytic community assembly between the phyllosphere and rhizosphere on the Tibetan Plateau. These findings advance our knowledge of epiphytic microbial assembly and disentangle how host plants exploit the microbiome for improved performance and functioning in stressful alpine ecosystems.

Cadmium (Cd) contamination in agricultural soil brings severe health risks through the dietary intake of Cd-polluted crops. The comprehensive role of pectin in lowering Cd accumulation is investigated through low Cd accumulated (L) and high Cd accumulated (H) cultivars of L. sativa. The significantly different Cd contents in the edible parts of two L. sativa cultivars are accomplished by different Cd transportations. The pectin is the dominant responsive cell wall component according to significantly increased uronic acid contents and the differential Cd absorption between unmodified and modified cell wall. The chemical structure characterization revealed the decreased methyl esterification in pectin under Cd treatment compared with control. Significantly brighter LM19 relative fluorescence density and 40.82% decreased methanol in the root pectin of L cultivar under Cd treatment (p < 0.05) supported that the de-methyl esterification of root pectin is more significant in L cultivar than in H cultivar. The pectin de-methyl esterification of L cultivar is achieved by the upregulation of pectin esterases and the downregulation of pectin esterase inhibitors under Cd treatments, which has facilitated the higher Cd-binding of pectin. Our findings provide deep insight into the differential Cd accumulation of L. sativa cultivars and contribute to the understanding the pollutant behaviors in plants.

Plant growth and development are governed via signal networks that connect inputs from nutrient status, hormone signals, and environmental cues. Substantial researches have indicated a pivotal role of sugars as signalling molecules in plants that integrate external environmental cues and other nutrients with intrinsic developmental programmes regulated via multiple plant hormones. Therefore, plant growth and development are controlled through complication signalling networks. However, in many studies, to obtain more obviously experimental findings, excess concentrations of applied exogenous sugars have aggravated the complexity of this signalling networks. Once researchers underestimate this complexity, a series of contradictory or contrasting findings will be generated. More importantly, in terms of these contradictory findings, more contradictory study outcomings are derived. In this review, we carefully analyze some reports, and find that these reports have confused or neglected that the sugar-antagonism of ethylene signalling is specific or conditional. As a result, many contradictory conclusions are generated, which will in turn misdirect the scientific community.

Mangrove plants, which have evolved to inhabit tidal flats, may adjust their physiological and morphological traits to optimize their growth in saline habitats. Furthermore, the confined distribution of mangroves within warm regions suggests that warm temperature is advantageous to their growth in saline environments. We analyzed growth, morphology and respiratory responses to moderate salinity and temperature in a mangrove species, Rhizophora stylosa. The growth of R. stylosa was accelerated in moderate salinity compared with its growth in fresh water. Under warm conditions, the increased growth is accompanied by increased specific leaf area (SLA) and specific root length. Low temperature resulted in a low relative growth rate due to a low leaf area ratio and small SLA, regardless of salinity. Salinity lowered the ratio of the amounts of alternative oxidase to cytochrome c oxidase in the mitochondrial respiratory chain in leaves. Salinity enhanced the leaf respiration rate for maintenance, but under warm conditions this enhancement was compensated by a low leaf respiration rate for growth. In contrast, salinity enhanced overall leaf respiration rates at low temperature. Our results indicate that under moderate saline conditions R. stylosa leaves require warm temperatures to grow with a high rate of resource acquisition without enhancing respiratory cost.

Carnosic acid (CA) is recognized as an antioxidant that confers protection to plants against various forms of oxidative stress, including UV-B stress. However, limited research has been conducted to elucidate the molecular mechanisms underlying its defence against UV-B stress. In this study, we demonstrated that CA exhibits more efficacy compared to other antioxidants in UV-B resistance. Moreover, CA was found to enhance the accumulation of secondary metabolites in Arabidopsis leaves. Through the analysis of differentially expressed genes in response to UV-B stress with or without CA treatment, we uncovered that the exogenous application of CA effectively activates the flavonoid biosynthesis pathway in Arabidopsis to improve resistance of Arabidopsis to UV-B stress.

The abscisic acid (ABA) signaling pathway is essential for plant response to abiotic stresses and can be modulated positively or negatively by MAPKKK proteins. This study focuses on the functional characterization of CaMEKK17, a MAPKKK previously recognized for its rapid induction under drought stress. Functional analyses demonstrated that CaMEKK17 is an active serine/threonine kinase with a conserved catalytic domain that is crucial for its kinase activity. CaMEKK17 silencing in pepper plants resulted in reduced drought tolerance, characterized by increased transpirational water loss and impaired ABA-mediated stomatal closure. Conversely, CaMEKK17 overexpression in Arabidopsis increased kinase activity, enhancing ABA sensitivity and drought tolerance. Further investigation revealed that CaMEKK17 interacts with pepper group A type 2C protein phosphatases (PP2Cs), particularly CaAITP1 and CaAIPP1, which inhibit its kinase activity. Protein-protein interactions mediated inhibition by CaAITP1, whereas CaAIPP1 relied on its phosphatase activity. Double gene silencing of CaMEKK17 and CaAITP1 demonstrated that CaMEKK17 functions downstream of CaAITP1 in ABA-mediated drought tolerance. Taken together, our findings suggest that CaMEKK17 positively modulates drought tolerance in pepper plants but may be inhibited by PP2Cs.