Global biogeographic distribution of Bathyarchaeota in paddy soils.

Bathyarchaeota, known as key participants of global elements cycling, is highly abundant and diverse in the sedimentary environments. Bathyarchaeota has been the research spotlight on sedimentary microbiology; however, its distribution in arable soils is far from understanding. Paddy soil is a habitat similar to freshwater sediments, while the distribution and composition of Bathyarchaeota in paddy soils have largely been overlooked. In this study, we collected 342 in situ paddy soil sequencing data worldwide to illuminate the distribution patterns of Bathyarchaeota and explore their potential ecological functions in paddy soils. The results showed that Bathyarchaeota is the dominant archaeal lineage, and Bathy-6 is the most predominant subgroup in paddy soils. Based on random forest analysis and construction of a multivariate regression tree, the mean annual precipitation and mean annual temperature are identified as the factors significantly influencing the abundance and composition of Bathyarchaeota in paddy soils. Bathy-6 was abundant in temperate environments, while other subgroups were more abundant in sites with higher rainfall. There are highly frequent associations between Bathyarchaeota and methanogens and ammonia-oxidizing archaea. The interactions between Bathyarchaeota and microorganisms involved in carbon and nitrogen metabolism imply a potential syntrophy between these microorganisms, suggesting that members of Bathyarchaeota could be important participants of geochemical cycle in paddy soils. These results shed light on the ecological lifestyle of Bathyarchaeota in paddy soils, and provide some baseline for further understanding Bathyarchaeota in arable soils. IMPORTANCE Bathyarchaeota, the dominant archaeal lineage in sedimentary environments, has been the spotlight of microbial research due to its vital role in carbon cycling. Although Bathyarchaeota has been also detected in paddy soils worldwide, its distribution in this environment has not yet been investigated. In this study, we conducted a global scale meta-analysis and found that Bathyarchaeota is also the dominant archaeal lineage in paddy soils with significant regional abundance differences. Bathy-6 is the most predominant subgroup in paddy soils, which differs from sediments. Furthermore, Bathyarchaeota are highly associated with methanogens and ammonia-oxidizing archaea, suggesting that they may be involved in the carbon and nitrogen cycle in paddy soil. These interactions provide insight into the ecological functions of Bathyarchaeota in paddy soils, which will be the foundation of future studies regarding the geochemical cycle in arable soils and global climate change.

Characterization of Starch in Cucurbita moschata Germplasms throughout Fruit Development.

Pumpkins (Cucurbita moschata; Cucurbitaceae) are the rich source of nutrients and valued for their biologically active substances to be used for the treatment of several diseases. The contents, composition, and conformation of starch are the significant quality traits of C. moschata. Two germplasms were targeted for analysis regarding the taste difference. Results indicated that the total starch contents and amylose/amylopectin ratio were high in CMO-X as compared to CMO-E during each fruit development stage. Scanning electron microscopy and transmission electron microscopy observations revealed that smooth surface starch granules fused together to enhance the starch accumulation. For a comparison of fruit development in CMO-E and CMO-X, the putative pathway for starch metabolism was developed and homologs were identified for each key gene involved in the pathway. GBSS and SBE were correlated with the difference in the amylose/amylopectin ratio of CMO-E and CMO-X. Conclusively, the developmental regulation of genes associated with starch accumulation can be considered as an important factor for the determination of fruit quality.

Metabolic and transcriptomic analysis of two Cucurbita moschata germplasms throughout fruit development.

BACKGROUND: Pumpkins (Cucurbita moschata; Cucurbitaceae) are valued for their fruits and seeds and are rich in nutrients. Carotenoids and sugar contents, as main feature of pumpkin pulp, are used to determine the fruit quality. RESULTS: Two pumpkin germplasms, CMO-X and CMO-E, were analyzed regarding the essential quality traits such as dry weight, soluble solids, organic acids, carotenoids and sugar contents. For the comparison of fruit development in these two germplasms, fruit transcriptome was analyzed at 5 different developmental stages from 0 d to 40 d in a time course manner. Putative pathways for carotenoids biosynthesis and sucrose metabolism were developed in C. moschata fruit and homologs were identified for each key gene involved in the pathways. Gene expression data was found consistent with the accumulation of metabolites across developmental stages and also between two germplasms. PSY, PDS, ZEP, CRTISO and SUS, SPS, HK, FK were found highly correlated with the accumulation of carotenoids and sucrose metabolites, respectively, at different growth stages of C. moschata as shown by whole transcriptomic analysis. The results of qRT-PCR analysis further confirmed the association of these genes. CONCLUSION: Developmental regulation of the genes associated with the metabolite accumulation can be considered as an important factor for the determination of C. moschata fruit quality. This research will facilitate the investigation of metabolic profiles in other cultivars.