Yang, C.-M. | bioRxiv Science

bioRxiv2021

The prevalence, predominance, and metabolic potentials of Candidatus Prochlorobium terpiosii in the coral-killing sponge, Terpios hoshinota

Terpios hoshinota is a ferocious, space-competing sponge that kills a variety of stony corals by overgrowth. Outbreaks of this species have led to intense coral reef damage and declines in living corals on the square kilometer scale in many geographical locations. Our large-scale 16S rRNA gene survey across three oceans revealed that the core microbiome of T. hoshinota included operational taxonomic units (OTUs) related to Prochloron, Endozoicomonas, Pseudospirillum, SAR116, Magnetospira, and Ruegeria. A Prochloron- related OTU was the most dominant cyanobacterium in T. hoshinota in the western Pacific Ocean, South China Sea, and Indian Ocean. The complete metagenome-assembled genome of the Prochloron-related cyanobacterium and our pigment analysis revealed that this bacterium had phycobiliproteins and phycobilins and lacked chlorophyll b, inconsistent with the iconic definition of Prochloron. Furthermore, the phylogenetic analyses based on 16S rRNA genes and 120 single-copy genes demonstrated that the bacterium was phylogenetically distinct to Prochloron, strongly suggesting that it should be a sister taxon to Prochloron; we therefore proposed this symbiotic cyanobacterium as a novel species under a new genus: Candidatus Paraprochloron terpiosii. With the recovery of the complete genome, we characterized the metabolic potentials of the novel cyanobacterium in carbon and nitrogen cycling and proposed a model for the interaction between Ca. Pp. terpiosi LD05 and T. hoshinota. In addition, comparative genomics analysis revealed that Ca. Paraprochloron and Prochloron showed distinct features in transporter systems and DNA replication. ImportanceThe finding that one species predominates cyanobacteria in T. hoshinota from different geographic locations indicates that this sponge and Ca. Pp. terpiosi LD05 share a tight relationship. This study builds the foundation for T. hoshinotas microbiome and paves a way for understanding the ecosystem, invasion mechanism, and causes of outbreak of this coral-killing sponge. Also, the first Prochloron-related complete genome enables us to study this bacterium with molecular approaches in the future and broadens our knowledge of the evolution of symbiotic cyanobacteria.

ecology↗

bioRxiv2020

Canopy micrometeorology monitoring in diverse climates innovatively improves the evaluation heat-induced sterility of rice under climate change

This study is the first and unique of open-field studies to assess the determination process of heat-induced spikelet sterility (HISS) of rice by using the same variety and the same monitoring system, MINCER (Micrometeorological Instrument for Near Canopy Environment of Rice), covering the major-rice growing regions from Sub-Saharan Africa, South, Southeast, and East Asia, and USA. Applying the observation data from the monitoring network, MINCERnet, to the canopy heat balance model, IM2PACT, it was quantitatively corroborated in open-field conditions worldwide that the canopy and panicle transpiration and their evaporative cooling effect played a great role on the micrometeorological gap between the ambient air temperature and the panicle temperature, and that the sterility rate due to HISS in open-fields can be evaluated accurately in diverse climates by the mean panicle temperature at flowering hours in the flowering period. The heat balance structure suggested that the risk of HISS should be higher in high humidity climates rather than in dry climates also in the future, which lead to the importance of the humidity accuracy as well as of the air temperature in climate scenarios and their spatial downscaling for future prediction of rice heat stress and production. Applying the heat-tolerant variety was suggested to be able to keep the sterility due to HISS low in all climates. It is needed of the approach using the panicle temperature as indicator of HISS by intervening sub-model and/or monitoring of micrometeorology inside the canopy to reduce uncertainties in future rice yield prediction under various adaptation measures.

plant biology↗