Publications

4381

ABSTRACT Huanglongbing (HLB) is a severe citrus disease in China caused by Candidatus Liberibacter asiaticus ( C Las). Since its initial identification, the pathogen has spread to 10 mainland provinces in China and caused devastating loss. Three distinct prophage types have been identified in C Las; however, their distribution and diversity in China remain inadequately understood. In this study, we collected 500 C Las samples from 10 provinces in China, employing three specific genomic loci to identify prophage types. Subsequently, Sanger sequencing was employed to analyze the genetic diversity of prophage within populations of C Las in China. In addition, the MaxEnt model optimized by the ENMeval software package, was used to predict the habitat suitability of populations of C Las and assess the potential impact of future climate change on its distribution in China. Our analysis revealed that type 2 prophage is the most prevalent, accounting for 55% in China. Among the 10 provinces tested, C Las populations in Yunnan and Sichuan demonstrated higher genetic diversity. Further analysis reveals that C Las populations harboring type 1 prophage remain relatively stable, whereas those carrying type 2 and type 3 prophages undergo population expansion. Furthermore, our predictive models indicate that the presently suitable habitat for C Las populations is concentrated in the southern and certain central regions of China, with an anticipated expansion under future climate change conditions. Presently, the center of populations of C Las characterized by favorable living conditions is situated in Zunyi City, Guizhou Province. Nevertheless, a projected trend indicates a shift toward the northeast, particularly targeting Tongren City in the foreseeable future. IMPORTANCE This study offers significant insights into the distribution and genetic diversity of three types of prophages associated with Candidatus Liberibacter asiaticus ( C Las) in China. Our predictions underscore the implications of climate change on the future distribution of C Las. These findings contribute to a better understanding of Huanglongbing management strategies and can facilitate the development of effective measures to control the spread of this devastating disease within the citrus industry.

Abstract Microbes perform critical functions in corals, yet most knowledge is derived from the photic zone. Here, we discover two mollicutes that dominate the microbiome of the deep-sea octocoral, Callogorgia delta, and likely reside in the mesoglea. These symbionts are abundant across the host’s range, absent in the water, and appear to be rare in sediments. Unlike other mollicutes, they lack all known fermentative capabilities, including glycolysis, and can only generate energy from arginine provided by the coral host. Their genomes feature several mechanisms to interact with foreign DNA, including extensive CRISPR arrays and restriction-modification systems, which may indicate their role in symbiosis. We propose the novel family Oceanoplasmataceae which includes these symbionts and others associated with five marine invertebrate phyla. Its exceptionally broad host range suggests that the diversity of this enigmatic family remains largely undiscovered. Oceanoplasmataceae genomes are the most highly reduced among mollicutes, providing new insight into their reductive evolution and the roles of coral symbionts.