Annual review of phytopathology最新文献

Plant viruses are obligate intracellular pathogens that hijack host cellular machinery to support their replication and spread. Viral infection induces a variety of structural and physiological changes in the plant as a result of viral biology and its interplay with host processes; these alterations can manifest as visible disruptions of normal growth and development, like stunting, leaf curling, chlorosis, or necrosis, which we recognize as disease symptoms. Despite their significant economic impact, the molecular mechanisms behind symptoms remain poorly understood, and their biological significance is in most cases still unclear. This review explores the possible sources of viral symptoms in plants, their elucidated molecular underpinnings, and the potential implications of symptom development for viral infection and ecology as well as plant health.

Significant advances have been made in understanding mechanisms of plant defense against biotrophic and necrotrophic pathogens. Whole-genome sequencing of these pathogens has uncovered the genetic underpinnings of the distinct and common virulence and defense mechanisms. Necrotrophic pathogens produce toxins, necrosis-inducing proteins, secondary metabolites, and hydrolytic enzymes, and their virulence generates endogenous plant peptides. The recognition of these factors triggers broad-spectrum quantitative resistance. Resistance to specialist, host-specific, toxin-producing pathogens is mediated by the absence of host susceptibility proteins, including nucleotide-binding leucine-rich repeats (NLRs), or by detoxification mechanisms. Biotrophic pathogens utilize distinct virulence strategies, and NLR proteins are critical determinants of resistance, interacting synergistically with other quantitative resistance factors. However, NLRs are ineffective against necrotrophs, which exploit canonical immune responses to establish and promote disease. Immune responses such as hypersensitive cell death and the production of reactive oxygen species and accumulation of hormones exhibit distinct or complex roles in defense against biotrophic and necrotrophic pathogens. Lately, the microbiome has become instrumental in uncovering novel pathogen resistance mechanisms. However, further studies are needed to understand the genes involved in recruiting defense-promoting microbes and their impact on pathogens with distinct virulence. Overall, a comprehensive understanding of mechanisms of resistance to biotrophic and necrotrophic pathogens is crucial for activating or suppressing appropriate host responses.

Vegetatively propagated crops such as cassava, potato, sweetpotato, and yam, or roots and tubers (RTs), play a major role in food security in low- and middle-income countries, yet phytosanitary issues in the tropics lead to substantial yield and quality losses. Challenges to production include institutional limitations that prevent effective responses and potential buildup of pathogens during clonal propagation. Addressing these challenges in a climate change context and diverse sociocultural environments requires a multifaceted approach, including improving access and availability to clean seed by strengthening seed systems; breeding for host resistance and disseminating resistant varieties; strengthening on-farm seed management; and designing effective policies and regulations to deal with seedborne diseases. Vital cross-cutting activities that can help to tackle the phytosanitary challenges of RTs include capacity strengthening, research on emergent pathogens, and improving regional cooperation and harmonization of phytosanitary standards to manage transboundary seed movement.

Rust fungi (order Pucciniales) form the largest group of plant pathogens. Early studies addressed infection processes and heritability of virulence but were limited by the complexity of these organisms. We present six lessons highlighting major discoveries about rust genome biology. First, during their main infectious stage, rusts carry two haploid genomes that can be highly heterozygous, and each genome is packaged in its own nucleus. Remarkably, this allows for the exchange of whole nuclei. Second, haploid genome size is extremely variable, ranging from ∼75 Mb to 1 GB. Third, genome expansions are driven by repetitive elements, but genomes are not compartmentalized. Fourth, although chromosome number and biotrophy-related gene content are conserved across the order, effectors are highly divergent in sequence. Fifth, resolution of the mating-type locus highlights its role in genetic exchange in populations. Sixth, individual haplotypes can now be tracked to reveal nuclear exchange events, delivering unprecedented insights into rust epidemiology.

Necrotrophic bacteria within the order Enterobacterales cause significant agricultural losses, with few effective management options available for producers. These pathogens have evolved at least two distinct strategies for infecting plants. Soft rot pathogens in the family Pectobacteriaceae, such as Dickeya and Pectobacterium, rely on secreting plant cell wall-degrading enzymes. In contrast, Pantoea necrotrophs depend on the production of phosphonate phytotoxins, a type of secondary metabolite, for their pathogenicity. This review summarizes recent discoveries on the virulence mechanisms of bacterial necrotrophs and current knowledge of factors that influence their host range and interactions with plant immune defenses. A deeper understanding of bacterial necrotroph host range determinants could inform the development and deployment of enhanced genetic resistance strategies.

Wheat yields have continued to increase globally at a steady pace over the past decade despite challenges faced by breeding programs from evolving and migrating races of rust and other wheat disease-inducing fungi. Additionally, pathogens are becoming tolerant to fungicides because of their injudicious use. We highlight the challenges in breeding and deploying resistant varieties and discuss global strategies to protect wheat from diseases. The continuous identification, utilization, and deployment of diverse resistance genes and quantitative trait loci for durable adult plant resistance, supported by precision phenotyping, marker-assisted and genomic selection, real-time pathogen diagnostics, and the rapid diffusion of resistant varieties, are helping to minimize crop losses while enhancing productivity. The potential for genetic engineering, including the introduction of resistance gene cassettes and precise genome editing of susceptibility or resistance genes, has also increased because of the recent acceptance of genetically modified wheat carrying the HB4® drought tolerance gene in some countries.

Postharvest biological control based on the use of microbial antagonists has been the subject of research and development for more than three decades. Several formulated products have been developed; however, their widespread use has not been realized, which has led to the development of new concepts and paradigms to better describe, understand, and employ biocontrol systems under commercial conditions. In the first part of this review, the evolution of postharvest biocontrol and its current status are briefly discussed. This is followed by a discussion of new concepts of postharvest disease and biocontrol systems based on studies of the microbiome of fruits and vegetables during development, harvest, and storage. A deeper understanding of the assembly, composition, interactive dynamics, and functional impact of microbial communities will enable the development of strategies to manipulate/engineer beneficial microbial assemblages that effectively suppress infection and disease development in harvested fresh fruit and vegetables.

Clubroot, a destructive disease of Brassicaceae, is caused by the soilborne, biotrophic protist Plasmodiophora brassicae. The pathogen was first identified by Mikhail Woronin in 1875 and named turnip disease in England. This pathogen has a unique, multiphase life cycle that takes place largely within a living host; however, it can also persist as resting spores in the soil for several years. P. brassicae pathotypes have strong adaptability, enabling them to overcome host resistance. Sustainable control requires an integrated approach, combining resistant cultivars, crop rotations, and soil amendment to optimize soil pH. The complexity and severity of clubroot have led to research efforts over the past 145 years, yielding significant advances in integrated disease management. Here, we discuss recent discoveries in the pathogenesis of P. brassicae, focusing on pathogen distribution, genetic diversity, trends in host-pathogen interactions, and advancements in genomics and effector biology as well as approaches to disease management.

Plant pathogens secrete effectors to facilitate infection and manipulate host physiological and immune responses. Effector proteins are challenging to characterize because of their sequence and functional diversity, rapid evolution, and host-specific interactions. Recent advances in artificial intelligence (AI), particularly in protein biology, offer new opportunities for identifying and characterizing effector proteins and understanding their evolutionary processes. This review discusses recent progress in applying AI to effector biology, focusing on identification, functional characterization, and evolution. Key areas include subcellular localization prediction, protein structural modeling with tools like AlphaFold, and the use of pretrained protein language models. AI promises to complement existing experimental and computational approaches and further accelerate the investigation of effector protein functions and their evolutionary histories, even in the absence of clear sequence similarity or known functional domains.

The birth of modern plant disease epidemiology can be traced back to 1963, coinciding with the first international gathering of epidemiologists and the publication of Vanderplank's landmark treatise, Plant Diseases: Epidemics and Control. Over the past six decades, the field has evolved in numerous ways, with ever-increasing use of mathematics, statistics, and computational methods, although many of the epidemiological principles expounded by Vanderplank remain valid. Two broad subdivisions can be seen in quantitative epidemiology: (a) theoretical and semiempirical modeling of the temporal, spatial, and spatiotemporal dynamics of disease and (b) prediction or forecasting of epidemics (or disease outbreaks, or the need for control interventions) on a real-time basis based on environmental (and other) data, usually using empirical models. Progress in both subdisciplines has been tied to new developments in the field of statistics and computer hardware and software as well as to advances in machine learning and artificial intelligence. This article provides reflections on some of the major developments in the field over the past 60+ years.