Geraniol is an important contributor to the pleasant floral scent of tea products and one of the most abundant aroma compounds in tea plants; however, its biosynthesis and physiological function in response to stress in tea plants remain unclear. The proteins encoded by the full-length terpene synthase (CsTPS1) and its alternative splicing isoform (CsTPS1-AS) could catalyze the formation of geraniol when GPP was used as a substrate in vitro, whereas the expression of CsTPS1-AS was only significantly induced by Colletotrichum gloeosporioides and Neopestalotiopsis sp. infection. Silencing of CsTPS1 and CsTPS1-AS resulted in a significant decrease of geraniol content in tea plants. The geraniol content and disease resistance of tea plants were compared when CsTPS1 and CsTPS1-AS were silenced. Down-regulation of the expression of CsTPS1-AS reduced the accumulation of geraniol, and the silenced tea plants exhibited greater susceptibility to pathogen infection than control plants. However, there was no significant difference observed in the geraniol content and pathogen resistance between CsTPS1-silenced plants and control plants in the tea plants infected with two pathogens. Further analysis showed that silencing of CsTPS1-AS led to a decrease in the expression of the defense-related genes PR1 and PR2 and SA pathway-related genes in tea plants, which increased the susceptibility of tea plants to pathogens infections. Both in vitro and in vivo results indicated that CsTPS1 is involved in the regulation of geraniol formation and plant defense via alternative splicing in tea plants. The results of this study provide new insights into geraniol biosynthesis and highlight the role of monoterpene synthases in modulating plant disease resistance via alternative splicing.

The OVATE gene family is a new class of transcriptional repressors, which play an important regulatory role in plant growth and development. Many studies have proved that the OVATE gene family can regulate the development of plant tissues and organs and resist stress, but its quantity and functional role in Rosa roxburghii remain unknown. In this study, 14 OVATE family members were identified by re-annotating the genome of Rosa roxburghii, and these members were unevenly distributed on 6 chromosomes. Evolutionary analysis indicated that these family members were classified into three groups. In their promoter regions, many hormone-related cis-acting elements such as ABA, GA, and MeJA were identified. Segmental duplication is an important driving force for the expansion of the OVATE family in Rosa roxburghii. Transcriptome sequencing and RT-qPCR analysis showed that OVATE gene family had a specific tissue expression pattern in Rosa roxburghii. For instance, the expression level of gene Rr602241 in leaves was more than 4 times that of other tissues. The gene Rr101515 was highly expressed in FR1 and FR4 stages of fruit tree development, and was highly homologous to the gene regulating fruit shape in tomatoes. These results suggest that members of the OVATE gene family may have diverse functions in different tissues. Furthermore, based on the transcriptome data of eight tissues, a transcriptional regulatory co-expression network of different transcription factors and 14 OVATE genes was constructed. In conclusion, our study provides the expression profiles of the OVATE family and reveals the potential functional roles of different members in the growth and development of Rosa roxburghii Tratt.

The OVATE gene family plays an important role in regulating the development of plant organs and resisting stress, but its expression characteristics and functions in sorghum have not been revealed. In this study, we identified 26 OVATE genes in the sorghum BTx623 genome, which were divided into four groups and distributed unevenly across 9 chromosomes. Evolutionary analysis showed that after differentiation between sorghum and Arabidopsis, the OVATE gene family may have experienced unique expansion events, and all OVATE family members were negatively selected. Transcriptome sequencing and RT-qPCR results showed that OVATE genes in sorghum showed diverse expression characteristics, such as gene SORBl_3001G468900 and SORBl_3009G173400 were significantly expressed in seeds, while SORBI_3005G042700 and SORBI_3002G417700 were only highly expressed in L1. Meantime, in the promoter region, a large number of hormone-associated cis-acting elements were identified, and these results suggest that members of the OVATE gene family may be involved in regulating specific development of sorghum leaves and seeds. This study improves the understanding of the OVATE gene family of sorghum and provides important clues for further exploration of the function of the OVATE gene family.

Background: PYL (Pyrabactin resistance 1-like) protein is a receptor of abscisic acid (ABA), which plays an important role in ABA signaling and influences plant growth and development and stress response. However, studies on PYL gene family in tea plants have not been reported. Results: In this study, we identified 20 PYL genes from the reference genome of tea plant (‘Shuchazao’). Phylogeny analysis indicated that PYLs from tea and other plant species were clustered into seven groups. The promoter region of PYL genes contains a large number of cis-elements related to hormones and stresses. A large number of PYL genes responding to stress were found by analyzing the expression levels of abiotic stress and biotic stress transcriptome data. For example, CSS0047272.1 were up-regulated by drought stress, and CSS0027597.1 could respond to both anthracnose disease and geometrid feeding treatments. In addition, 10 PYL genes related to growth and development were verified by RT-qPCR and their tissue expression characteristics were revealed. Conclusions: Our results provided a comprehensive characteristic of the PYL gene family in tea plants and provided an important clue for further exploring its functions in the growth and development, and resistance to stress of tea plants.

Non-volatile metabolites and aroma substances are important quality components of tea plants, yet the quality characteristics of tea plants with special leaf colors still await further revelation. In this study, by integrating five analytical methods including widely targeted metabolomics, HS-SPME-GC–MS, and targeted metabolomics, a total of 1770 non-volatile metabolites were detected in ZK, NB, and ZH3, among which flavonoids, amino acids, and polyphenols were the main differential metabolites. The contents of total catechins, anthocyanins and amino acids in ZK, NB and ZH3 are 159.96, 122.03, 121.86 mg/g, 4.22, 4.77, 4.70 mg/g and 22.27, 60.01 and 61.83 mg/g, respectively. A total of 122 volatile compounds were identified, mainly including 36 alcohols, 20 aldehydes, 16 esters and 16 ketones. And 41, 36 and 37 key aroma compounds were identified in NB, ZH3 and ZK, respectively. These results provide valuable insights into understanding the quality basis of tea plants with different leaf colors.

OVATE genes are a new class of transcriptional repressors with important regulatory roles in plant growth and development. Through genome-wide analysis of the OVATE gene family of tea plants, 26 and 13 family members were identified in cultivated and ancient tea plants, respectively. Syntenic results showed that OVATE gene family in cultivated tea plants may have experienced a special expansion event. Based on phylogenetic tree analysis, all OVATE genes were divided into four groups, and the third group had the largest number, reaching 16. Transcriptome data from different organs and populations indicated that many OVATE family members were highly expressed in young shoots and leaves, and their expression levels gradually decreased as tea leaves developed. Finally, the expression trends of the six key candidate genes were verified by RT-qPCR, which were consistent with the transcriptome results, indicating that the ovate gene family plays an important role in regulating the process of tea leaf development. In addition, we identified a key structural variation with a length of 184 bp, and the population genotyping showed that it was closely related to the area of tea leaves. Our research provides an important clue for further exploring the function of ovate gene family in tea plants and the development mechanism of tea leaves.