ABSTRACT
Tartary buckwheat [Fagopyrum tataricum (L.) Gaertn.] is a pseudocereal with strongly abiotic resistance. NACs, one of the largest plant-specific transcription factors (TFs), are involved in various stress responses. However, the characteristics and regulatory mechanisms of NAC TFs remain unclarified clearly in Tartary buckwheat (TB). In this study, it validated that salt, drought, and abscisic acid (ABA) stress significantly up-regulated the expression of NAC TF gene FtNAC31. Its coding protein has a C-terminal transactivated domain and localized in the nucleus, suggesting that FtNAC31 might play a transcriptional activation role in TB. Notably, overexpression of FtNAC31 lowered the seed germination rate upon ABA treatment and enhanced the tolerance to salt and drought stress in transgenetic Arabidopsis. Furthermore, under various stresses, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in FtNAC31 overexpressed lines exhibited a sharp increase trend. Meanwhile, the expression levels of several stress-associated genes including RD29A, RD29B, RD22, DREB2B, NCED3, and POD1, were dramatically upregulated in lines overexpressing FtNAC31. Altogether, overproduction of FtNAC31 could enhance the resistance to salt and drought stresses in transgenic Arabidopsis, which most likely functioned in an ABA-dependent way.
Subject(s)
Arabidopsis , Fagopyrum , Abscisic Acid/metabolism , Arabidopsis/metabolism , Catalase/metabolism , Droughts , Fagopyrum/genetics , Fagopyrum/metabolism , Gene Expression Regulation, Plant , Plant Proteins/genetics , Plant Proteins/metabolism , Plants, Genetically Modified/metabolism , Sodium Chloride/metabolism , Sodium Chloride/pharmacology , Stress, Physiological/genetics , Superoxide Dismutase/metabolism , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
BACKGROUND: Fagopyrum (Polygonaceae) is a small plant lineage comprised of more than fifteen economically and medicinally important species. However, the phylogenetic relationships of the genus are not well explored, and the characteristics of Fagopyrum chloroplast genomes (plastomes) remain poorly understood so far. It restricts the comprehension of species diversity in Fagopyrum. Therefore, a comparative plastome analysis and comprehensive phylogenomic analyses are required to reveal the taxonomic relationship among species of Fagopyrum. RESULTS: In the current study, 12 plastomes were sequenced and assembled from eight species and two varieties of Fagopyrum. In the comparative analysis and phylogenetic analysis, eight previously published plastomes of Fagopyrum were also included. A total of 49 plastomes of other genera in Polygonaceae were retrieved from GenBank and used for comparative analysis with Fagopyrum. The variation of the Fagopyrum plastomes is mainly reflected in the size and boundaries of inverted repeat/single copy (IR/SC) regions. Fagopyrum is a relatively basal taxon in the phylogenomic framework of Polygonaceae comprising a relatively smaller plastome size (158,768-159,985 bp) than another genus of Polygonaceae (158,851-170,232 bp). A few genera of Polygonaceae have nested distribution of the IR/SC boundary variations. Although most species of Fagopyrum show the same IRb/SC boundary with species of Polygonaceae, only a few species show different IRa/SC boundaries. The phylogenomic analyses of Fagopyrum supported the cymosum and urophyllum groups and resolved the systematic position of subclades within the urophyllum group. Moreover, the repeat sequence types and numbers were found different between groups of Fagopyrum. The plastome sequence identity showed significant differences between intra-group and inter-group. CONCLUSIONS: The deletions of intergenic regions cause a short length of Fagopyrum plastomes, which may be the main reason for plastome size diversity in Polygonaceae species. The phylogenomic reconstruction combined with the characteristics comparison of plastomes supports grouping within Fagopyrum. The outcome of these genome resources may facilitate the taxonomy, germplasm resources identification as well as plant breeding of Fagopyrum.
Subject(s)
Fagopyrum , Genome, Chloroplast , Polygonaceae , Evolution, Molecular , Fagopyrum/genetics , Genome, Chloroplast/genetics , Phylogeny , Plant Breeding , Polygonaceae/geneticsABSTRACT
Anthocyanins confer the red color in the hypocotyl of tartary buckwheat sprouts. Uridine diphosphate (UDP)-glucose:flavonoid 3-O-glycosyltransferase (UFGT) stabilizes anthocyanin by attaching the glucosyl moiety from UDP-glucose to the C3 hydroxyl of anthocyanin. In this study, we characterized three UFGT-like genes, designated FtUFGT1, 2, and 3 from tartary buckwheat. The results revealed that FtUFGT1, FtUFGT2, and FtUFGT3 can convert cyanidin to cyanidin 3-O-glucoside, with specific activities of 20.01 × 10(-3), 8.93 × 10(-3), and 20.24 × 10(-3) IU/mg, respectively. The active-site residues of the C-terminal domains and the N-terminal domains are important for the donor and acceptor recognition of these proteins. The expression of the three FtUFGTs paralleled the tissue-specific anthocyanin accumulation. After cold treatment, the increased content of anthocyanin was accompanied by the up-regulated expression of the three FtUFGTs. Among these three UGFT gene members, FtUFGT3 showed the highest expression level and the highest specific activity, suggesting that FtUFGT3 might be the major gene involved in anthocyanin biosynthesis. These results suggested that the FtUFGT genes, FtUFGT3 in particular, might be important candidates for anthocyanin formation in tartary buckwheat sprouts.
Subject(s)
Fagopyrum/enzymology , Glucosyltransferases/genetics , Plant Proteins/genetics , Anthocyanins/metabolism , Cold Temperature , Fagopyrum/genetics , Fagopyrum/growth & development , Fagopyrum/metabolism , Gene Expression Regulation, Plant , Glucosyltransferases/metabolism , Plant Proteins/metabolism , Seeds/enzymology , Seeds/genetics , Seeds/growth & development , Seeds/metabolism , Stress, PhysiologicalABSTRACT
KEY MESSAGE: Eight R2R3 - MYB genes in tartary buckwheat were identified, and their expression patterns were comprehensively analyzed, which reveals role in plant response to abiotic stresses. The proteins of the R2R3-MYB superfamily play key roles in the growth and development processes as well as defense responses in plants. However, their characteristics and functions have not been fully investigated in tartary buckwheat (Fagopyrum tataricum), a strongly abiotic resistant coarse cereal. In this article, eight tartary buckwheat R2R3-MYB genes were isolated with full-length cDNA and DNA sequences. Phylogenetic analysis of the members of the R2R3-MYB superfamily between Arabidopsis and tartary buckwheat revealed that the assumed functions of the eight tartary buckwheat R2R3-MYB proteins are divided into five Arabidopsis functional subgroups that are involved in abiotic stress. Expression analysis during abiotic stress and exogenous phytohormone treatments identified that the eight R2R3-MYB genes responded to one or more treatments. This study is the first comprehensive analysis of the R2R3-MYB gene family in tartary buckwheat under abiotic stress.