Tea is an important global beverage crop and is largely clonally propagated. Despite previous studies on the species, its genetic and evolutionary history deserves further research. Here, we present a haplotype-resolved assembly of an Oolong tea cultivar, Tieguanyin. Analysis of allele-specific expression suggests a potential mechanism in response to mutation load during long-term clonal propagation. Population genomic analysis using 190 Camellia accessions uncovered independent evolutionary histories and parallel domestication in two widely cultivated varieties, var. sinensis and var. assamica. It also revealed extensive intra- and interspecific introgressions contributing to genetic diversity in modern cultivars. Strong signatures of selection were associated with biosynthetic and metabolic pathways that contribute to flavor characteristics as well as genes likely involved in the Green Revolution in the tea industry. Our results offer genetic and molecular insights into the evolutionary history of Camellia sinensis and provide genomic resources to further facilitate gene editing to enhance desirable traits in tea crops.

A Bacillus-like isolate, strain FJAT-13831(T), isolated from the No. 1 pit soil of Emperor Qin's Terra-cotta Warriors in Xi'an City, China, was studied to determine its taxonomic status. Dominant fatty acids of this organism included iso-C15:0, iso-C17:0, C16:0, iso-C13:0, anteiso-C15:0, and iso-C17:1ω5c. Comparative 16S rRNA gene sequence analysis confirmed the affiliation of this isolate to the genus Bacillus and indicated that it was closely related to Bacillus pseudomycoides DSM 12442(T) (99.72 % similarity). A phylogenetic analysis of the gyrB gene sequence similarities exhibited independent clustering of the isolate FJAT-13831(T) and showed 93.8 % (<95 %) sequence similarity with its closest phylogenetic neighbour B. pseudomycoides DSM 12442(T). Separate standing of the strain FJAT-13831(T) was supported by a whole genome-based phylogenetic analysis with an average nucleotide identity value of 91.47 (<95 %) between isolate FJAT-13831(T) and B. pseudomycoides DSM 12442(T) and was consistent with the results of DNA-DNA hybridization (69.1 % relatedness). These findings support the conclusion that the isolate FJAT-13831(T) represents a novel species, for which the name Bacillus bingmayongensis sp. nov. is proposed. The type strain is FJAT-13831(T) (= CGMCC 1.12043(T) = DSM 25427(T)).

The Bacterial community structure and its complexity of the enrichment culture during the isolation and screening of imidacloprid-degrading strain were studied using denaturating gradient gel electrophoresis analysis. The dominant bacteria in the original tea rhizosphere soil were uncultured bacteria, Rhizobium sp., Sinorhizobium, Ochrobactrum sp., Alcaligenes, Bacillus sp., Bacterium, Klebsiella sp., and Ensifer adhaerens. The bacterial community structure was altered extensively and its complexity reduced during the enrichment process, and four culturable bacteria, Ochrobactrum sp., Rhizobium sp., Geobacillus stearothermophilus, and Alcaligenes faecalis, remained in the final enrichment. Only one indigenous strain, BCL-1, with imidacloprid-degrading potential, was isolated from the sixth enrichment culture. This isolate was a gram-negative rod-shaped bacterium and identified as the genus Ochrobactrum based on its morphological, physiological, and biochemical properties and its 16S rRNA gene sequence. The degradation test showed that approximately 67.67% of the imidacloprid (50 mg/l) was degraded within 48 h by strain BCL-1. The optimum conditions for degradation were a pH of 8 and 30°C. The simulation of imidacloprid bioremediation by strain BCL-1 in soil demonstrated that the best performance in situ (tea soil) resulted in the degradation of 92.44% of the imidacloprid (100 mg/g) within 20 days, which was better than those observed in the ex situ simulations that were 64.66% (cabbage soil), 41.15% (potato soil), and 54.15% (tomato soil).