Plant, Cell & Environment最新文献

The rhizosphere is a key interface between plants, microbes and the soil which influences plant health and nutrition and modulates terrestrial biogeochemical cycling. Recent research has shown that the rhizosphere environment is far more dynamic than previously recognised, with evidence emerging for diurnal rhythmicity in rhizosphere chemistry and microbial community composition. This rhythmicity is in part linked to the host plant's circadian rhythm, although some heterotrophic rhizosphere bacteria and fungi may also possess intrinsic rhythmicity. We review the evidence for diurnal rhythmicity in rhizosphere microbial communities and its link to the plant circadian clock. Factors which may drive microbial rhythmicity are discussed, including diurnal change in root exudate flux and composition, rhizosphere physico-chemical properties and plant immunity. Microbial processes which could contribute to community rhythmicity are considered, including self-sustained microbial rhythms, bacterial movement into and out of the rhizosphere, and microbe-microbe interactions. We also consider evidence that changes in microbial composition mediated by the plant circadian clock may affect microbial function and its significance for plant health and broader soil biogeochemical cycling processes. We identify key knowledge gaps and approaches which could help to resolve the spatial and temporal variation and functional significance of rhizosphere microbial rhythmicity. This includes unravelling the factors which determine the oscillation of microbial activity, growth and death, and cross-talk with the host over diurnal time frames. We conclude that diurnal rhythmicity is an inherent characteristic of the rhizosphere and that temporal factors should be considered and reported in rhizosphere studies.

Transpirational cooling is crucial for plant thermal regulation to avoid overheating; however, during prolonged and/or acute heat stress it often necessitates stomatal closure to reduce the risk of hydraulic failure due to dehydration. The intricate interplay between thermal regulation, water transport and use may govern plant performance in water-limited and simultaneously heat-stressed environments, yet this remains inadequately understood. Here, in a common garden, we evaluated the functional associations among physiological characteristics related to leaf thermoregulation, heat tolerance, xylem water transport, and stomatal regulation in eight shrub species commonly used for fixing active sand dunes in northern China. Our study showed that traits associated with heat adaptation and xylem hydraulics were closely related to stomatal regulation. More isohydric shrub species with higher water transport efficiency possessed stronger transpirational cooling capacity; whereas the more anisohydric species demonstrated greater tolerance to overheating. Moreover, leaf heat tolerance was strongly coordinated with drought tolerance reflected by leaf turgor loss point. These results underscore the importance of stomatal regulation in shaping plant thermal adaptive strategies and provide valuable insights into the coupling of water and heat-related physiological processes in plants adapted to sandy land environments prone to combined drought and heat stresses.

In the context of climate change, associated with increasingly frequent water deficits and heat waves, there is an urgent need to maintain the performance of soybean, a leading legume crop worldwide, before its yield declines. The objective of this study was to explore which plant traits improve soybean tolerance to heat and/or water stress, with a focus on traits involved in plant architecture and nutrient uptake. For this purpose, two soybean genotypes were grown under controlled conditions in a high-throughput phenotyping platform where either optimal conditions, heat waves, water stress or both heat waves and water stresses were applied during the vegetative stage. By correlating architectural to functional traits, related to water, carbon allocation and nutrient absorption, we were able to explain the stress susceptibility level of the two genotypes. We have shown that water flow in the plant is central to the uptake and allocation of mineral elements in the plant, despite its modulation by stress and in a genotype-dependent manner. This cross-analysis of plant ecophysiology and plant nutrition under different stresses provides new information, especially on the importance of mineral elements in the different plant organs, and can inform future crop design, particularly under changing climatic conditions.

A fascinating feature of land plants is their ability to continually initiate new tissues and organs throughout their lifespan, driven by a pool of pluripotent stem cells located in meristems. In seed plants, various types of meristems are initiated and maintained during the sporophyte generation, while their gametophytes lack meristems and rely on sporophyte tissues for growth. In contrast, seed-free vascular plants, such as ferns, develop meristems during both the sporophyte and gametophyte generations, allowing for the independent growth of both generations. Recent findings have highlighted both conserved and lineage-specific roles of the HAIRY MERISTEM (HAM) family of GRAS-domain transcriptional regulators in various meristems throughout the land plant lifecycle. Here, we review and discuss how HAM genes maintain meristem indeterminacy in both sporophytes and gametophytes, with a focus on studies performed in two model species: the flowering plant Arabidopsis thaliana and the fern Ceratopteris richardii. Additionally, we summarize the crucial and tightly regulated functions of the microRNA171 (miR171)-HAM regulatory modules, which define HAM spatial patterns and activities during meristem development across various meristem identities in land plants.

The availability of nitrogen (N) can dramatically influence crops resistance to herbivorous insects. However, the interaction between N fertilization and crop resistance to insects is not well understood. In this study, the effects of N fertilization on the grain aphid (Sitobion miscanthi) were investigated using three wheat (Triticum aestivum) cultivars with different aphid resistances. We measured aphid life cycle parameters, fecundity, survival rate, weight and feeding behavior, in conjunction with wheat metabolomics, transcriptomics and alien introgression analysis. Our results demonstrated that higher N application benefits aphid feeding across all three wheat cultivars. We also reveal that the highly resistant cultivar (ZM9) can only exert its resistance-advantage under low N fertilization, losing its advantage compared to moderately resistant cultivar YN19 and susceptible cultivar YN23 under higher N fertilization. The effects of N fertilization on wheat-aphid interactions were due to changes in the regulation of carbon and nitrogen metabolism. Integration of multi-omics highlighted specific aphid-induced differentially expressed genes (DEGs, e.g., TUB6, Tubulin 6; ENODL20, Early nodulin-like protein 20; ACT7 Actin 7; Prx47, Peroxidase 47) and significantly different metabolites (SDMs, e.g., crotonoside, guanine, 2'-O-methyladenosine, ferulic acid) in ZM9. Additionally, we report the unique SDMs-DEGs interactions, associated with introgression during wheat domestication, may help infer aphid resistance. In summary, this study provides new insights into the relationships between N fertilization practices, defense responses and integrated pest management for sustainable wheat production.

Norway spruce is an important coniferous species in boreal forests. Root and stem rot diseases caused by the necrotrophic pathogen Heterobasidion parviporum threaten the wood production of Norway spruce which necessitates the search for durable control and management strategies. Breeding for resistant traits is considered a viable long-term strategy. However, identification of potential resistant traits and markers remains a major challenge. In this study, short-term disease resistance screening was conducted using 218 Norway spruce clones from 17 families. Disease resistance was evaluated based on the size of necrosis lesion length following infection with the pathogen. A subset of needles/branches from clones with small (partial resistant) or large (susceptible) lesions were used for terpene analysis and transcriptomic profiling. The results revealed that the content of monoterpene linalool and 1,8-cineole and their respective encoded genes were significantly more abundant and highly expressed in the partial resistant group. Furthermore, linalool and 1,8-cineole were demonstrated to have inhibitory effect on the growth of the pathogen H. parviporum, with morphological distortion of the hyphae. RNAseq analysis revealed that transcript of pathogen genes involved in the regulation of carbohydrate metabolism and stress responses were significantly decreased in presence of the terpenes. The results suggest the relevance of monoterpenes together with jasmonic acid precursor and some genes involved in phenylpropanoid biosynthesis, as constitutive tolerance factors for Norway spruce tolerance against necrotrophic pathogen. The high level of necrosis related cell death gene expression might be factors critical for host susceptibility and disease development.

Aluminum (Al) toxicity in acidic soils leads to a considerable reduction in crop yields. MicroRNAs play essential roles in abiotic stress responses, but little is known of their role in the response of peanut (Arachnis hypogea L.) to Al stress. In this study, a novel Ah-miR2916 (miR2916)-AhERF13-AhSUC3 module was found to be involved in the Al-stress response via ethylene-mediated signaling in peanut. Overexpression of miR2916 in Arabidopsis resulted in reduced Al tolerance by downregulating ethylene biosynthesis, while knockdown miR2916 in peanut enhanced Al tolerance. Notably, the APETALA2/ethylene-responsive factor (ERF), AhERF13, was identified as a potential target of miR2916. AhERF13 expression was increased in miR2916 knockdown peanut lines and displayed an opposing pattern to that of miR2916 under Al stress. Consistently, knockdown AhERF13 peanut lines indicated that AhERF13 positively regulates Al tolerance by upregulating ethylene biosynthesis. AhERF13 was shown capable of binding to an ERF motif in the promoter region of sucrose transport protein 3 (AhSUC3) and positively regulate its expression. Consequently, AhSUC3 improved Al tolerance by upregulating ethylene biosynthesis. These results provide further insights into the molecular mechanisms operating during peanut response to Al stress, and suggests targets for manipulation in breeding programs for improved Al tolerance.

Plants in the understory experience climatic conditions affected by the overstory canopy that influence physiological and biochemical processes. Here, we investigate the relationships of leaf lipid molecular abundances to leaf water content, transmitted irradiance, and free-air temperature (T_air) from deciduous angiosperm (Quercus buckleyi) and evergreen gymnosperm (Juniperus ashei) understory trees across an elevation gradient in a central Texas (USA) woodland. Monthly sampling from 04/2019 to 01/2020 revealed that long-chain leaf waxes (≥ C₂₇) accumulated with leaf water deficit over the growing season for both tree species. Higher transmitted light during the hottest, driest months was due to a decreased leaf area index (LAI) in the canopy as leaf shedding is a common drought response. Isoprenoids (sesqui-, di-terpenoids, phytosterols) in leaves changed by month with changing LAI and transmittance associated with monthly T_air changes. The chain length of n-alkanols in Q. buckleyi shifted with seasonal LAI at different topographic positions. The unsaturation of fatty acids in both tree species decreased with increased seasonal T_air but showed topography sensitivity. Leaf-level metabolites responded to understory microclimatic variables that were influenced by seasonality and topography.

Rose (Rosa rugosa) is an important perfume plant, but its cultivation is significantly constrained by salt stress. Terpenes represent the most abundant volatile aromatic compounds in roses, yet little is known about how terpene metabolism responds to salt stress. In this study, salt-treated rose petals presented significant accumulation of monoterpenes, including geraniol, due to the disruption of jasmonic acid (JA) biosynthesis and signalling. Overexpression and silencing analyses revealed a MYC transcription factor involved in JA signalling (RrbHLH105) as a repressor of geraniol biosynthesis. RrbHLH105 was shown to activate the trehalose-6-phosphate synthase genes RrTPS5 and RrTPS8 by binding to the E-box (5'-CANNTG-3'). The increased trehalose-6-phosphate content and decreased geraniol content in rose petals overexpressing TPS5 or RrTPS8, along with the high accumulation of geraniol in petals where both RrbHLH105 and TPSs were cosilenced, indicate that trehalose signalling plays a role in the negative regulation of geraniol accumulation via the RrbHLH105-TPS module. In summary, the suppression of RrbHLH105 by salt stress leads to excessive geraniol accumulation through the inhibition of both RrbHLH105-mediated JA signalling and RrTPS-mediated trehalose signalling in rose petals. Additionally, this study highlights the emerging role of RrbHLH105 as a critical integrator of JA and trehalose signalling crosstalk.

Understanding the reciprocal interaction between root development and coadapted beneficial microbes in response to elevated CO₂ (eCO₂) will facilitate the identification of nutrient-efficient cultivars for sustainable agriculture. Here, systematic morphological, anatomical, chemical and gene expression assays performed under low-nitrogen conditions revealed that eCO₂ drove the development of the endodermal barrier with respect to L-/S-shaped lateral roots (LRs) in rice. Next, we applied metabolome and endodermal-cell-specific RNA sequencing and showed that rice adapts to eCO₂ by spatially recruiting diazotrophs via flavonoid secretion in L-shaped LRs. Using the rice Casparian strip mutant Oscasp1-1, we confirmed that reduced lignin deposition selectively recruits the diazotrophic family of Oxalobacteraceae to confer tolerance to low nitrogen availability.