文献类型：期刊文献

英文题名：Comparative analysis of NR and NiR gene families reveals nitrite formation mechanisms in two Toona species

作者：Wei, Yi[1,2] Dai, Jianhua[1] Fan, Yanru[1] Yin, Hengfu[1] Liu, Jun[1] Han, Xiaojiao[1]

第一作者：Wei, Yi

通信作者：Liu, J[1];Han, XJ[1]

机构：[1]Chinese Acad Forestry, Res Inst Subtrop Forestry, Hangzhou 311400, Peoples R China;[2]Nanjing Forestry Univ, Acad Forestry, Nanjing 210037, Peoples R China

年份：2025

卷号：12

期号：1

外文期刊名：CHEMICAL AND BIOLOGICAL TECHNOLOGIES IN AGRICULTURE

收录：;Scopus(收录号：2-s2.0-85218207888);WOS:【SCI-EXPANDED(收录号:WOS:001402124200001)】；

基金：The authors would like to express their sincere gratitude to collaborators and lab members for their invaluable guidance, support, and encouragement throughout the course of this research.

语种：英文

外文关键词：Toona sinensis; Toona ciliata; Nitrate reductase gene (NR); Nitrite reductase gene (NiR); Gene expression; Transient expression

摘要：BackgroundToona sinensis and Toona ciliata both belong to the same genus in the Meliaceae family; however, the nitrate and nitrite contents in T. sinensis are significantly higher than those in T. ciliata. Given the growing emphasis on dietary health, it has become imperative to implement breeding strategies to reduce the excessive nitrite levels in T. sinensis. Nitrate reductase (NR) and nitrite reductase (NiR) are crucial enzymes in plant nitrogen metabolism. In this study, we employed a comparative analysis of the NR and NiR gene families in T. sinensis and T. ciliata. By integrating bioinformatics and expression pattern assessments, we aimed to elucidate the underlying factors contributing to the variance in nitrate and nitrite levels between these two species.ResultsT. sinensis exhibited higher nitrate and nitrite contents than T. ciliata. Through comprehensive genome-wide analysis, we identified two TsNRs and two TsNiRs in T. sinensis, compared to one TcNiR and two TcNiRs in T. ciliata, suggesting an expansion of NR members in T. sinensis relative to T. ciliata. The NR and NiR proteins in T. sinensis and T. ciliata share high sequence similarity and exhibit close genetic relationships with their counterparts in Populus trichocarpa and Salix purpurea. The exon-intron structures and conserved motifs of these genes were stringently conserved throughout evolutionary history. All the seven NR and NiR genes in both T. sinensis and T. ciliata harbor various cis-regulatory elements within their promoter sequences, which are associated with development, stress response, and hormonal regulation. Furthermore, the expression of TsNiR and TcNiR genes was also found to be tissue-specific. Among them, TcNR1 and TsNR2 exhibited the highest expression observed in mature leaves. Especially, the expression level of TsNR2 in mature leaves was 400-fold higher than in other tissues. In addition, transient overexpression of TsNiR1 and TsNiR2 in T. sinensis significantly reduced nitrite content.ConclusionsThe higher nitrite accumulation in T. sinensis compared to T. ciliata is attributed to its lower nitrite reductase activity, the expansion of the NR gene family, and the elevated expression of TsNR2 in the leaves.