The chromosome-scale reference genome of Rubus chingii Hu provides insight into the biosynthetic pathway of hydrolyzable tannins.

Rubus chingii Hu (Fu-Pen-Zi), a perennial woody plant in the Rosaceae family, is a characteristic traditional Chinese medicinal plant because of its unique pharmacological effects. There are abundant hydrolyzable tannin (HT) components in R. chingii that provide health benefits. Here, an R. chingii chromosome-scale genome and related functional analysis provide insights into the biosynthetic pathway of HTs. In total, sequence data of 231.21 Mb (155 scaffolds with an N50 of 8.2 Mb) were assembled into seven chromosomes with an average length of 31.4 Mb, and 33 130 protein-coding genes were predicted, 89.28% of which were functionally annotated. Evolutionary analysis showed that R. chingii was most closely related to Rubus occidentalis, from which it was predicted to have diverged 22.46 million years ago (Table S8). Comparative genomic analysis showed that there was a tandem gene cluster of UGT, carboxylesterase (CXE) and SCPL genes on chromosome 02 of R. chingii, including 11 CXE, eight UGT, and six SCPL genes, which may be critical for the synthesis of HTs. In vitro enzyme assays indicated that the proteins encoded by the CXE (LG02.4273) and UGT (LG02.4102) genes have tannin hydrolase and gallic acid glycosyltransferase functions, respectively. The genomic sequence of R. chingii will be a valuable resource for comparative genomic analysis within the Rosaceae family and will be useful for understanding the biosynthesis of HTs.

A predicted protein functional network aids in novel gene mining for characteristic secondary metabolites in tea plant (Camellia sinensis).

Modeling a protein functional network in concerned species is an efficient approach for identifying novel genes in certain biological pathways. Tea plant (Camellia sinensis) is an important commercial crop abundant in numerous characteristic secondary metabolites (e.g., polyphenols, alkaloids, alkaloids) that confer tea quality and health benefits. Decoding novel genes responsible for tea characteristic components is an important basis for applied genetic improvement and metabolic engineering. Herein, a high-quality protein functional network for tea plant (TeaPoN) was predicted using cross-species protein functional associations transferring and integration combined with a stringent biological network criterion control. TeaPoN contained 31,273 nonredundant functional interactions among 6,634 tea proteins (or genes), with general network topological properties such as scale-free and small-world. We revealed the modular organization of genes related to the major three tea characteristic components (theanine, caffeine, catechin) in TeaPoN, which served as strong evidence for the utility of TeaPoN in novel gene mining. Importantly, several case studies regarding gene identification for tea characteristic components were presented. To aid in the use of TeaPoN, a concise web interface for data deposit and novel gene screening was developed (http://teapon.wchoda.com). We believe that TeaPoN will serve as a useful platform for functional genomics studies associated with characteristic secondary metabolites in tea plant.

Genomewide analysis of MATE-type gene family in maize reveals microsynteny and their expression patterns under aluminum treatment.

Multidrug and toxic compound extrusion (MATE) proteins are a group of secondary active transporters, which widely exist in all living organisms and play important role in the detoxication of endogenous secondary metabolites and exogenous agents. However, to date, no systematic and comprehensive study of this family is reported in maize. Here, a total of 49 MATE genes (ZmMATE) were identified and divided into seven groups by phylogenetic analysis. Conserved intro-exon structures and motif compositions were investigated in these genes. Results by gene locations indicated that these genes were unevenly distributed among all 10 chromosomes. Tandem and segmental duplications appeared to contribute to the expansion and evolution of this gene family. The Ka/Ks ratios suggested that the ZmMATE has undergone large-scale purifying selection on the maize genome. Interspecies microsynteny analysis revealed that there were independent gene duplication events of 10 ZmMATE. In addition, most maize MATE genes exhibited different expression profiles in diverse tissues and developmental stages. Sixteen MATE genes were chosen for further quantitative real-time polymerase chain reaction analysis showed differential expression patterns in response to aluminum treatment. These results provide a useful clue for future studies on the identification of MATE genes and functional analysis of MATE proteins in maize.