Dihydroflavonol 4-reductase (DFR, EC 1.1.1.219) is a rate-limited enzyme in the biosynthesis of anthocyanins and condensed tannins (proanthocyanidins) that catalyzes the reduction of dihydroflavonols to leucoanthocyanins. In this study, two full-length transcripts encoding for PtrDFR1 and PtrDFR2 were isolated from Populus trichocarpa. Sequence alignment of the two PtrDFRs with other known DFRs reveals the homology of these genes. The expression profile of PtrDFRs was investigated in various tissues of P. trichocarpa. To determine their functions, two PtrDFRs were overexpressed in tobacco (Nicotiana tabacum) via Agrobacterium-mediated transformation. The associated color change in the flowers was observed in all 35S:PtrDFR1 lines, but not in 35S:PtrDFR2 lines. Compared to the wild-type control, a significantly higher accumulation of anthocyanins was detected in transgenic plants harboring the PtrDFR1. Furthermore, overexpressing PtrDFR1 in Chinese white poplar (P. tomentosa Carr.) resulted in a higher accumulation of both anthocyanins and condensed tannins, whereas constitutively expressing PtrDFR2 only improved condensed tannin accumulation, indicating the potential regulation of condensed tannins by PtrDFR2 in the biosynthetic pathway in poplars.

Species are susceptible to infection by microbial pathogens that severely affect their growth and substantially decrease their economic value. In this study, two pathogenesis-related protein genes consisting of Beauveria bassiana chitinase (Bbchit1) and motherwort lipid-transfer protein (LJAMP2) were introduced into Chinese white poplar (Populus tomentosa Carr.) via Agrobacterium-mediated transformation using the hygromycin (hyg) and neomycin phosphotransferase (NPTII) genes as selectable markers, respectively. Polymerase chain reaction analysis confirmed the stable integration of transgenes in the genome of transgenic plants. In vitro assays showed that inhibitory activity against the fungal pathogen Alternaria alternata (Fr.) Keissler was evident from the crude leaf extracts from transgenic plants. Importantly, the double-transgenic plants exhibited significantly higher resistance to the pathogen than either of the single-gene transformants and wild-type plants when inoculated with A. alternata. The level of disease reduction in double-transgenic lines was between 82 and 95%, whereas that of single-gene transformants carrying either LJAMP2 or Bbchit1 was between 65 and 89%. These results indicated that the combined expression of the LJAMP2 and Bbchit-1 genes could significantly enhance resistance to necrotrophic fungal pathogens in poplar.

Sucrose synthase (SUS, EC 2.4.1.13) is a key enzyme involved in sucrose metabolism. In this study, amplification by polymerase chain reaction confirmed that there are at least seven SUS genes (BeSUS1-7) in the Bambusa emeiensis genome. The expression patterns of the BeSUSs genes differed from each other in various bamboo tissues. Among these BeSUSs, BeSUS2 was expressed predominately in the root and BeSUS5 was most abundant in developing shoots, indicating that these two isozymes might play more important physiological roles in root and shoot than the other BeSUSs genes, respectively. In addition, BeSUSs response to abscisic acid (ABA), methyl jasmonate (MeJA) and 2,6-dichlorobenzonitrile treatment (2,6-DCB, an inhibitor of cellulose synthesis) was also investigated in leaves. The results showed that the expression levels of the BeSUS1, 5 and 7 genes were not only conspicuously induced by ABA treatment but also up-regulated by exogenous application of MeJA, indicating that these three isozymes are most likely involved in ABA and MeJA stress responses and are important in meeting the increased glycolytic demand that occurs during these stresses. Moreover, after 2,6-DCB treatment, the cellulose content of leaves was decreased and the transcripts of BeSUS2, 3 and 7 were markedly decreased, while those of BeSUS 5 and 6 were conspicuously induced. The results suggest that the possible roles of BeSUSs genes in the pathway of sucrose metabolism, bamboo resistance to abiotic stresses and the regulation of cellulose biosynthesis may be divergent.

Amorphophallus konjac, as a significant representative of the Araceae family, demonstrates considerable potential for applications in medicine, healthcare, food, industry, and bioenergy due to its rich content of konjac glucomannan (KGM). However, the synthetic pathway of KGM remains largely unclear. Although genomic sequencing has been completed for various representative Araceae plants, including Amorphophallus konjac, a comprehensive data platform for deep analysis and exploration of the functions of these genes is lacking. In the current work, genomic and transcriptomic data from multiple Araceae species were integrated, and a database, AraceaeDB (http://www.araceaedb.com/), was constructed specifically for analyzing and comparing gene functions in Araceae plants. The gene functions in the database were annotated in detail, and their ortholog groups were identified and classified into different functional modules based on their expression patterns across various transcriptomic datasets. Multiple functional genomics analysis tools were developed, including OrthoGroup analysis, BLAST search, co-expression analysis, KEGG/GO enrichment analysis, and the JBrowse visualization tool. Moreover, the database incorporates several medicinally significant bioactive compounds traditionally important in the Araceae family, providing target prediction capabilities for these compounds. Furthermore, the major biosynthetic pathway of KGM has been successfully elucidated through these database resources, and a key gene AkCSL3 has been identified. It has been further confirmed that overexpression of AkCSL3 can significantly increase the content of KGM, suggesting its potential crucial role in the polymerization process of glucomannan in konjac corms.

Tritium is the main component of radioactive wastewater and can be migrated into organisms to form OBT, which may pose a potential risk to aquatic ecosystem. Hence, it is essential to monitor OBT conversion in the presence of tritium exposure. In this study, the effects of pretreatment methods such as digestion on the recovery of tritium were discussed. It was found that microwave digestion pretreatment could improve the recovery of tritium by up to 90% and allow OBT measurement with a small sample size equivalent to about 60 mg (dry weight). In addition, the efficiency of OBT transformation was different among biological samples, and the radiation hormesis phenomenon was induced by low-dose tritium exposure in microalgae Chlorella vulgaris . Low-dose tritium exposure may induce radiation hormesis through the reactive oxygen species signaling pathway, thus improving the photosynthetic capacity and metabolism level of C. vulgaris . Furthermore, enhancement of photorespiration metabolism and the antioxidation system may be important means for C. vulgaris to balance damage by low doses of tritium radiation. This study provides insights for further investigating OBT behavior, and will contribute to understanding the equilibrium damage mechanism of algae exposed to low doses of tritium.