Exposure to a variety of environmental factors such as salinity, drought, metal toxicity, extreme temperature, air pollutants, ultraviolet-B (UV-B) radiation, pesticides, and pathogen infection leads to subject oxidative stress in plants, which in turn affects multiple biological processes via reactive oxygen species (ROS) generation. ROS include hydroxyl radicals, singlet oxygen, and hydrogen peroxide in the plant cells and activates signaling pathways leading to some changes of physiological, biochemical, and molecular mechanisms in cellular metabolism. Excessive ROS, however, cause oxidative stress, a state of imbalance between the production of ROS and the neutralization of free radicals by antioxidants, resulting in damage of cellular components including lipids, nucleic acids, metabolites, and proteins, which finally leads to the death of cells in plants. Thus, maintaining a physiological level of ROS is crucial for aerobic organisms, which relies on the combined operation of enzymatic and nonenzymatic antioxidants. In order to improve plants’ tolerance towards the harsh environment, it is vital to reinforce the comprehension of oxidative stress and antioxidant systems. In this review, recent findings on the metabolism of ROS as well as the antioxidative defense machinery are briefly updated. The latest findings on differential regulation of antioxidants at multiple levels under adverse environment are also discussed here.

BackgroundThe NAC (NAM, ATAF1/2, and CUC2) transcription factor family represents a group of large plant-specific transcriptional regulators, participating in plant development and response to external stress. However, there is no comprehensive study on the NAC genes of Tartary buckwheat (Fagopyrum tataricum), a large group of extensively cultivated medicinal and edible plants. The recently published Tartary buckwheat genome permits us to explore all the FtNAC genes on a genome-wide basis.ResultsIn the present study, 80 NAC (FtNAC) genes of Tartary buckwheat were obtained and named uniformly according to their distribution on chromosomes. Phylogenetic analysis of NAC proteins in both Tartary buckwheat and Arabidopsis showed that the FtNAC proteins are widely distributed in 15 subgroups with one subgroup unclassified. Gene structure analysis found that multitudinous FtNAC genes contained three exons, indicating that the structural diversity in Tartary buckwheat NAC genes is relatively low. Some duplication genes of FtNAC have a conserved structure that was different from others, indicating that these genes may have a variety of functions. By observing gene expression, we found that FtNAC genes showed abundant differences in expression levels in various tissues and at different stages of fruit development.ConclusionsIn this research, 80 NAC genes were identified in Tartary buckwheat, and their phylogenetic relationships, gene structures, duplication, global expression and potential roles in Tartary buckwheat development were studied. Comprehensive analysis will be useful for a follow-up study of functional characteristics of FtNAC genes and for the development of high-quality Tartary buckwheat varieties.Electronic supplementary materialThe online version of this article (10.1186/s12864-019-5500-0) contains supplementary material, which is available to authorized users.

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Background AP2/ERF transcription factors perform indispensable functions in various biological processes, such as plant growth, development, biotic and abiotic stresses responses. The AP2/ERF transcription factor family has been identified in many plants, and several AP2/ERF transcription factors from Arabidopsis thaliana ( A. thaliana ) have been functionally characterized. However, little research has been conducted on the AP2/ERF genes of tartary buckwheat ( Fagopyum tataricum ), which is an important edible and medicinal crop. The recently published whole genome sequence of tartary buckwheat allowed us to study the tissue and expression profiles of AP2/ERF genes in tartary buckwheat on a genome-wide basis. Results In this study, 134 AP2/ERF genes of tartary buckwheat ( FtAP2/ERF ) were identified and renamed according to the chromosomal distribution of the FtAP2/ERF genes. According to the number conserved domains and gene structure, the AP2/ERF genes were divided into three subfamilies by phylogenetic tree analysis, namely, AP2 (15 members), ERF (116 members) and RAV (3 members). A total of 10 motifs were detected in tartary buckwheat AP2/ERF genes, and some of the unique motifs were found to be important for the function of AP2/ERF genes. Conclusion A comprehensive analysis of AP2/ERF gene expression patterns in different tissues and fruit development stages by quantitative real-time PCR (qRT-PCR) showed that they played an important role in the growth and development of tartary buckwheat, and genes that might regulate flower and fruit development were preliminarily identified. This systematic analysis establishes a foundation for further studies of the functional characteristics of FtAP2/ERF genes and improvement of tartary buckwheat crops. Electronic supplementary material The online version of this article (10.1186/s12870-019-1681-6) contains supplementary material, which is available to authorized users.

Background GRAS are plant-specific transcription factors that play important roles in plant growth and development. Although the GRAS gene family has been studied in many plants, there has been little research on the GRAS genes of Tartary buckwheat ( Fagopyrum tataricum ), which is an important crop rich in rutin. The recently published whole genome sequence of Tartary buckwheat allows us to study the characteristics and expression patterns of the GRAS gene family in Tartary buckwheat at the genome-wide level. Results In this study, 47 GRAS genes of Tartary buckwheat were identified and divided into 10 subfamilies: LISCL, HAM, DELLA, SCR, PAT1, SCL4/7, LAS, SHR, SCL3, and DLT. FtGRAS genes were unevenly distributed on 8 chromosomes, and members of the same subfamily contained similar gene structures and motif compositions. Some FtGRAS genes may have been produced by gene duplications; tandem duplication contributed more to the expansion of the GRAS gene family in Tartary buckwheat. Real-time PCR showed that the transcription levels of FtGRAS were significantly different in different tissues and fruit development stages, implying that FtGRAS might have different functions. Furthermore, an increase in fruit weight was induced by exogenous paclobutrazol, and the transcription level of the DELLA subfamily member FtGRAS22 was significantly upregulated during the whole fruit development stage. Therefore, FtGRAS22 may be a potential target for molecular breeding or genetic editing. Conclusions Collectively, this systematic analysis lays a foundation for further study of the functional characteristics of GRAS genes and for the improvement of Tartary buckwheat crops. Electronic supplementary material The online version of this article (10.1186/s12870-019-1951-3) contains supplementary material, which is available to authorized users.