Terpenoids are a wide variety of natural products and terpene synthase (TPS) plays a key role in the biosynthesis of terpenoids. Mentha plants are rich in essential oils, whose main components are terpenoids, and their biosynthetic pathways have been basically elucidated. However, there is a lack of systematic identification and study of TPS in Mentha plants. In this work, we genome-widely identified and analyzed the TPS gene family in Mentha longifolia, a model plant for functional genomic research in the genus Mentha. A total of 63 TPS genes were identified in the M. longifolia genome sequence assembly, which could be divided into six subfamilies. The TPS-b subfamily had the largest number of genes, which might be related to the abundant monoterpenoids in Mentha plants. The TPS-e subfamily had 18 members and showed a significant species-specific expansion compared with other sequenced Lamiaceae plant species. The 63 TPS genes could be mapped to nine scaffolds of the M. longifolia genome sequence assembly and the distribution of these genes is uneven. Tandem duplicates and fragment duplicates contributed greatly to the increase in the number of TPS genes in M. longifolia. The conserved motifs (RR(X)8W, NSE/DTE, RXR, and DDXXD) were analyzed in M. longifolia TPSs, and significant differentiation was found between different subfamilies. Adaptive evolution analysis showed that M. longifolia TPSs were subjected to purifying selection after the species-specific expansion, and some amino acid residues under positive selection were identified. Furthermore, we also cloned and analyzed the catalytic activity of a single terpene synthase, MlongTPS29, which belongs to the TPS-b subfamily. MlongTPS29 could encode a limonene synthase and catalyze the biosynthesis of limonene, an important precursor of essential oils from the genus Mentha. This study provides useful information for the biosynthesis of terpenoids in the genus Mentha.

Glycerol-3-phosphate acyltransferases (GPATs) play an important role in glycerolipid biosynthesis, and are mainly involved in oil production, flower development, and stress response. However, their roles in regulating plant height remain unreported. Here, we report that Arabidopsis GPAT1 is involved in the regulation of plant height. GUS assay and qRT-PCR analysis in Arabidopsis showed that GPAT1 is highly expressed in flowers, siliques, and seeds. A loss of function mutation in GPAT1 was shown to decrease seed yield but increase plant height through enhanced cell length. Transcriptomic and qRT-PCR data revealed that the expression levels of genes related to gibberellin (GA) biosynthesis and signaling, as well as those of cell wall organization and biogenesis, were significantly upregulated. These led to cell length elongation, and thus, an increase in plant height. Together, our data suggest that knockout of GPAT1 impairs glycerolipid metabolism in Arabidopsis, leading to reduced seed yield, but promotes the biosynthesis of GA, which ultimately enhances plant height. This study provides new evidence on the interplay between lipid and hormone metabolism in the regulation of plant height.

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Anthocyanins, a subclass of flavonoids, are key pigments responsible for diverse flower colors in plants. While the role of anthocyanin synthase (ANS) genes in regulating anthocyanin accumulation is well established in model plants, their evolutionary diversification and expression patterns in Nymphaea colorata remain largely unexplored. This study systematically identified 32 ANS genes (NcANS) from the N. colorata genome and analyzed their physicochemical properties, gene structures, evolutionary relationships, promoter cis-acting elements, and expression patterns across blue, red, and white petals. Synteny analysis demonstrated conserved and species-specific expansion of ANS genes across plant species. Phylogenetic analysis grouped these genes into seven subfamilies, suggesting functional diversification. Expression profiling and RT-qPCR validation revealed specific NcANS genes with higher expression in blue petals, highlighting their potential roles in pigment accumulation. These findings provide critical insights into anthocyanin biosynthesis in N. colorata and lay a foundation for future molecular breeding aimed at flower color modification.

C2H2-type zinc finger protein (C2H2-ZFP) transcription factors play evident roles in regulating plant growth and development and abiotic stress responses. However, the role of C2H2-ZFP from Mentha canadensis remains uncertain. We identified the multifunctional C2H2-ZFP gene McZFP1 from M. canadensis based on phylogenetic analysis. The McZFP1 gene was highly expressed in stems, responding to abiotic stress and phytohormone treatments. McZFP1 localized in the nucleus and showed no transcriptional autoactivation activity in yeast. McZFP1 overexpression in Arabidopsis thaliana significantly reduced the number of trichomes and root hairs, root hair length, and salt stress tolerance. Further study revealed that McZFP1 overexpression increased the expression of negative regulator genes and decreased that of positive regulator genes to inhibit plant trichome and root hair development. Malondialdehyde accumulation was promoted, but the proline content and catalase, superoxide dismutase, and peroxidase activities were reduced and the expression of stress response genes was inhibited in McZFP1 overexpression lines under salt treatment, thereby compromising plant salt tolerance. Overall, these results indicate that McZFP1 is a novel C2H2-ZFP transcription factor that plays negative roles in trichome and root hair development and salt stress tolerance.