Plant, Cell & Environment最新文献

Legume plants can interact with nitrogen-fixing rhizobia bacteria and arbuscular mycorrhizal fungi (AMF) simultaneously, forming a tripartite symbiotic association. Co-inoculation studies performed on a variety of legumes have shown that rhizobia and AMF influence each other when they co-occur in tripartite association and affect host plant nutrition and performance. Although single plant-microbe interactions have been extensively studied, our understanding in the field of tripartite interactions is insufficient and current knowledge cannot predict the symbiotic outcome, which appears to depend on many parameters. In this review we examine the current state of research on the legume-rhizobium-AMF tripartite symbiosis. We investigate the dynamic interaction between the two microsymbionts and the effect of one microbe on the other, both at the physiological and the molecular levels, and the result of dual inoculation on host plant growth, fitness and response to stresses. Rhizobia and AMF interact both extraradically and intraradically, effects on microbe and host plant gene expression levels are observed, AMF positively regulates nodulation, while rhizobia can affect AMF root colonisation either positively or negatively. Factors observed to regulate the establishment and function of the tripartite symbiosis, such as the rhizobia-AMF combination, host plant identity and environmental conditions are discussed.

How different stress responses by male and female plants are influenced by interactions with rhizosphere microbes remains unclear. In this study, we employed poplar as a dioecious model plant and quantified biotic associations between microorganisms to explore the relationship between microbial associations and plant adaptation. We propose a health index (HI) to comprehensively characterize the physiological characteristics and adaptive capacity of plants under stress. It was found that male poplars demonstrated higher salt stress tolerance than females, and root-secreted citric acid was significantly higher in the rhizospheres of male poplars. Positive biotic association among bacteria increased poplar HI significantly under salt stress, while fungal and cross-domain biotic association (bacteria-fungi) did not. We further identified a keystone bacterial taxon regulating bacterial biotic association, ASV_22706, which was itself regulated by citric acid and significantly positively correlated with host HI. The abundance of keystone fungal taxa was positively correlated with HI of male poplars and negatively correlated with HI of female poplars. Compared with female poplars, male poplars enriched more prebiotics and probiotics under stress. This work primarily reveals the relationship between adaptation differences and microbial interactions in dioecious plants, which suggests a microbial approach to improve plant adaptability to stress conditions.

Outside Front Cover: The cover image is based on the article Identification and Characterization of Innate Immunity in Actinidia melanandra in Response to Pseudomonas syringae pv. actinidiae by Jay Jayaraman et al., https://doi.org/10.1111/pce.15189.

Heat stress and pathogens are two serious yield-limiting factors of crop plants. Plants that previously experienced high but sub-lethal temperatures become subsequently tolerant to higher temperatures through the development of acquired thermotolerance (ATT). ATT activation is associated with the elevated expression of heat shock (HS)-related genes such as HSFA2, HSFA3, and HSP101. Similarly, through the development of systemic acquired resistance (SAR), previously experienced plants achieve a higher resistance than naïve plants. SAR activation requires mobile signals and primarily depends on salicylic acid (SA) signaling. Studies to understand the interaction between ATT and SAR are limiting. To investigate the possible interconnection, we studied cross-protection between SAR and ATT on 4-week-old soil-grown Arabidopsis plants. We observed localized pathogen inoculation provides thermotolerance. Pathogens activate the expressions of HSFA2, HSFA3, HSA32, and HSP101 in pathogen-free systemic tissues. Interestingly, pathogen-induced SAR activation is impaired in hsfa2, hsfa3, and hsp101 mutants, suggesting these HS memory genes are essential for SAR induction. In contrast, thermopriming by exposing plants to sublethal temperatures, blocks SAR activation by pathogens. Thermopriming suppresses SAR mobile signal generation, accumulation of SA, and PR1 gene expression in systemic leaves. Altogether, our results demonstrate a complex interaction between SAR and ATT induction pathways in plants.

Low temperature is a limiting environmental factor for tea plant growth and development. CBL-interacting protein kinases (CIPKs) are important components of the calcium pathway and involved in plant development and stress responses. Herein, we report the function and regulatory mechanisms of a low-temperature-inducible gene, CsCIPK20, in tea plants. The overexpression of CsCIPK20 in Arabidopsis and its transient knockdown in tea plants confirmed its positive role in cold resistance. Notably, the ascorbic acid (AsA) levels increased in the overexpression lines and decreased in the CsCIPK20 knockdown tea plants under freezing stress. Transcriptomic analysis revealed that genes involved in flavonoid metabolism, glutathione metabolism, and AsA biosynthesis were significantly regulated by CsCIPK20. Furthermore, we found that CsCSN5, a key component of the COP9 signalosome, interacted with CsCIPK20 to mediate CsCIPK20 degradation. CsCSN5 interacted with CsVTC1, a key enzyme in AsA biosynthesis, and mediated CsVTC1 degradation. Knockdown of CsVTC1 in tea plants enhanced sensitivity to low temperature. Moreover, we demonstrated that CsCIPK20 competed with CsVTC1 to bind to CsCSN5, which protected CsVTC1 from degradation mediated by CsCSN5 and contributed to AsA accumulation. Overall, our findings uncovered a mechanistic framework through which the CsCIPK20-CsCSN5-CsVTC1 module mediated AsA accumulation and low-temperature resistance in tea plants.

Wheat (Triticum aestivum L.) is one of the most important staple crops all over the world. Its productivity is adversely affected by aphid infestation. Plant volatiles play a critical role in plant communication, inducing direct and indirect defenses against insect pests. However, little is known about the priming mechanism of key volatiles in wheat. To determine whether and how plant volatile induced defense priming in wheat against the grain aphid Sitobion avenae, a combination of insect bioassays, phytohormone and defense metabolite quantification, and transcriptome analyses were performed using an important aphid damage-induced plant volatile, methyl salicylate (MeSA). MeSA treatment primed wheat for enhanced accumulation of salicylic acid, flavonoid and benzoxazinoids (BXs), and increased resistance to S. avenae and attractiveness to an aphid parasitoid Aphelinus asychis. Supplementation with a BX (2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one) and two flavonoids (xanthohumol and isobavachalcone) in artificial diet impaired the survival, development and fecundity of S. avenae. Moreover, MeSA treatment induced wheat volatile emission especially MeSA. Functional investigation of odorant-binding proteins (OBPs) in A. asychis revealed that AasyOBP4 is responsible for the recognition of MeSA. Taken together, our results provide insights into the molecular mechanism of MeSA-mediated defense in wheat and propose MeSA as a phytoprotectant for crop protection and sustainable agriculture.

Corner's rules are well known in describing inter-specific scaling relationships for plant organ size-related traits, from species with thick terminal stems, large leaves, and sparsely branched twigs to species with opposite traits; however, the implications of organ size on physiological functions and growth performance of trees remain unclear. Moreover, whether Corner's rules spectra differ between tree species with simple and compound leaves is not known. Here, we measured key twig morphological traits, physiological characteristics, and radial growth rates of 27 simple- and 6 compound-leaved tree species in a common garden in Northeast China. The size scaling relationships between leaf lamina and supporting structures were mostly allometric (slope < 1) in simple-leaved species. In contrast, such relationships were predominantly isometric (slope = 1) in compound-leaved species. Consistently, twig hydraulic conductance and photosynthetic rate increased significantly faster as twig size increased across the compound-leaved species. Consequently, compound-leaved species equipped with twigs of fewer but larger leaves have the potential to achieve remarkably high growth rates. Our study revealed divergent investment-return strategies between the two functional groups, that is, 'diminishing returns' in simple-leaved species and 'stable returns' in compound-leaved species, and identified mechanistic associations among twig architecture, physiological characteristics and tree growth rate.

Heading date of rice (Oryza sativa) is a key factor determining rice production and regional adaptability. We analysed the molecular mechanism of OsPIL15, encoding phytochrome-interacting factor-like protein, in delaying rice heading date. Overexpression of OsPIL15 delayed rice heading date by upregulating Hd1 and inhibiting Hd3a and RFT1 expression. OsLF, encoding one rice heading repressor, was found to be the putative candidate regulated by OsPIL15 through a chromatin immunoprecipitation sequencing assay and a transcriptome sequencing assay. OsPIL15 could directly bind to the OsLF promoter and activated its expression. Knocking-out OsLF in OsPIL15-overexpressing lines resulted in flowering 2-3 days earlier, partially rescuing the delayed phenotype. This indicates that overexpression of OsPIL15 overexpression delays heading date partially through OsLF. Protein-protein interaction assay of OsPIL15 or OsPIL15-∆APB (OsPIL15 lacking the active phytochrome B [phyB]-binding [APB] motif) with PHYB showed that the APB motif was required for the interaction between OsPIL15 and PHYB. Furthermore, overexpression of either OsPIL15-∆APB in the wild type or OsPIL15 in the phyB mutant did not delay rice heading date under natural long-day conditions, suggesting that phyB influences OsPIL15-mediated delay in rice heading date.

Extreme cold events, becoming more frequent, affect plant growth and development. Much is known about C-repeat binding transcription factor (CBF)-dependent cold-signaling pathways in plants. However, the CBF-independent regulatory pathway in angiosperms is unclear, and the cold-signaling pathways in non-angiosperms lacking CBFs, such as the extremely cold-tolerant desert moss Syntrichia caninervis, are largely unknown. In this study, we determined that fully hydrated S. caninervis without cold acclimation could tolerate a low-temperature of -16°C. Transcriptome analysis of S. caninervis under 4°C and -4°C treatments revealed that sugar and energy metabolism, lipid metabolism and antioxidant activity were altered in response to cold stress, and surprisingly, most photosynthesis-related genes were upregulated under cold treatment. Transcription factors analysis revealed that A-5 DREB genes, which share a common origin with CBFs, are the hubs in the freezing-stress response of S. caninervis, in which ScDREBA5 was upregulated ~1000-fold. Overexpressing ScDREBA5 significantly enhanced freezing tolerance in both S. caninervis and Physcomitrium patens by upregulating genes involved in photosynthetic and antioxidant pathways. This is the first study to uncover the mechanism regulating the cold-stress response in S. caninervis. Our findings increase our understanding of different cold-stress response strategies in non-angiosperms and provide valuable genetic resources for breeding cold-tolerant crops.

The endoplasmic reticulum (ER) serves as the primary site for protein biosynthesis and processing, with ER homeostasis being essential for the survival of plant cells. Numerous studies have underscored the pivotal role of the ER as a battleground for host-pathogen interactions. Pathogens secrete effectors to subvert the host ER and manipulate ER-mediated defense responses, fostering an infection-permissive environment for their proliferation. Plants respond to these challenges by triggering ER stress responses, including the unfolded protein response (UPR), autophagy, and cell death pathways, to combat pathogens and ensure survival. Consequently, plants are faced with a life-or-death decision, directly influencing the outcomes of pathogen infection. In this review, recent advances in manipulating host ER homeostasis by pathogens are introduced, further key counteracting strategies employed by host plants to maintain ER homeostasis during infection are summarized, and finally, several pending questions the studies involving both parties in this evolving field are proposed.