Genome-wide investigation of UDP-Glycosyltransferase family in Tartary buckwheat (Fagopyrum tataricum).

BACKGROUND: Tartary buckwheat (Fagopyrum tataricum) belongs to Polygonaceae family and has attracted increasing attention owing to its high nutritional value. UDP-glycosyltransferases (UGTs) glycosylate a variety of plant secondary metabolites to control many metabolic processes during plant growth and development. However, there have been no systematic reports of UGT superfamily in F. tataricum. RESULTS: We identified 173 FtUGTs in F. tataricum based on their conserved UDPGT domain. Phylogenetic analysis of FtUGTs with 73 Arabidopsis UGTs clustered them into 21 families. FtUGTs from the same family usually had similar gene structure and motif compositions. Most of FtUGTs did not contain introns or had only one intron. Tandem repeats contributed more to FtUGTs amplification than segmental duplications. Expression analysis indicates that FtUGTs are widely expressed in various tissues and likely play important roles in plant growth and development. The gene expression analysis response to different abiotic stresses showed that some FtUGTs were involved in response to drought and cadmium stress. Our study provides useful information on the UGTs in F. tataricum, and will facilitate their further study to better understand their function. CONCLUSIONS: Our results provide a theoretical basis for further exploration of the functional characteristics of FtUGTs and for understanding the growth, development, and metabolic model in F. tataricum.

Exploration of unique starch physicochemical properties of novel buckwheat lines created by crossing Golden buckwheat and Tatary buckwheat.

Buckwheat is considered as a healthy cereal food, and it is essential to cultivate new buckwheat lines with good starch physicochemical properties for both consumers and food producers. Six novel buckwheat (Duoku, Dk) were generated by crossing of Golden buckwheat and Tatary buckwheat, and their kernel appearance properties and starch physicochemical properties were analyzed together with one domestic line (Cimiqiao) and one wild line (Yeku). The results showed that Dk samples had better appearance properties than two control samples. The Dk samples showed lower amylose content, similar amylopectin molecular structure and chain length distributions, and larger starch granules compared with Cimiqiao. The digestion results showed that two Dk samples: Dk6 & Dk9 had high resistant starch content; while the other two Dk samples: Dk37 & Dk38 had a steady glucose releasing rate. The Dk samples also showed high gelatinization temperature, indicating they were good raw materials for producing glass noodle. This study proved that Dk buckwheat had unique starch physicochemical properties, and could be used as new food materials in the future.

The role of NaHS pretreatment in improving salt stress resistance in foxtail millet seedlings: physiological and molecular mechanisms.

Salt stress is a prevailing abiotic stress in nature, with soil salinization becoming a pressing issue worldwide. High soil salinity severely hampers plant growth and leads to reduced crop yields. Hydrogen sulfide (H2S), a gas signal molecule, is known to be synthesized in plants exposed to abiotic stress, contributing to enhanced plant stress resistance. To investigate the impact of sodium hydrosulfide hydrate (NaHS, a H2S donor) on millet's response to salt stress, millet seedlings were subjected to pretreatment with 200 µM NaHS, followed by 100 mM NaCl stress under soil culture conditions. The growth, osmotic adjustment substances, antioxidant characteristics, membrane damage, and expression levels of related genes in millet seedlings were detected and analyzed. The results showed that NaHS pretreatment alleviated the inhibition of salt stress on the growth of foxtail millet seedlings, increased the proline content and antioxidant enzyme activities, as well as the expression levels of SiASR4, SiRPLK35 and SiHAK23 genes under salt stress. These findings demonstrated that NaHS pretreatment can enhance salt tolerance in foxtail millet seedlings by regulating the content of osmotic adjustment substances and antioxidant enzyme activity, reducing electrolyte permeability, and activating the expression of salt-resistant genes.

Integrated transcriptome and metabonomic analysis of key metabolic pathways in response to cadmium stress in novel buckwheat and cultivated species.

Introduction: Buckwheat (Fagopyrum tataricum), an important food crop, also has medicinal uses. It is widely planted in Southwest China, overlapping with planting areas remarkably polluted by cadmium (Cd). Therefore, it is of great significance to study the response mechanism of buckwheat under Cd stress and further develop varieties with excellent Cd tolerance. Methods: In this study, two critical periods of Cd stress treatment (days 7 and 14 after Cd treatment) of cultivated buckwheat (Pinku-1, named K33) and perennial species (F. tatari-cymosum Q.F. Chen) (duoku, named DK19) were analyzed using transcriptome and metabolomics. Results: The results showed that Cd stress led to changes in reactive oxygen species (ROS) and the chlorophyll system. Moreover, Cd-response genes related to stress response, amino acid metabolism, and ROS scavenging were enriched or activated in DK19. Transcriptome and metabolomic analyses highlighted the important role of galactose, lipid (glycerophosphatide metabolism and glycerophosphatide metabolism), and glutathione metabolism in response to Cd stress in buckwheat, which are significantly enriched at the gene and metabolic levels in DK19. Discussion: The results of the present study provide valuable information for a better understanding of the molecular mechanisms underlying Cd tolerance in buckwheat and useful clues for the genetic improvement of drought tolerance in buckwheat.

Importance of amylose chain-length distribution in determining starch gelatinization and retrogradation property of wheat flour in the presence of different salts.

Although starch gelatinization and retrogradation properties of wheat flour have been studied with respect to their relations to starch structures, it remains less understood how starch structure and salt (a common food additive) together determine these properties. Gelatinization and retrogradation properties of seven wheat flours with distinct starch structures were thus investigated after adding different salts. NaCl most efficiently increased starch gelatinization temperatures, while KCl showed highest efficiency in retarding the retrogradation degree. Both gelatinization and retrogradation parameters were significantly affected by amylose structural parameters and types of salts. E.g., wheat flours with longer amylose long chains had more heterogeneous amylopectin double helices during gelatinization, while this relationship disappeared after adding NaCl. More amylose short chains increased the heterogeneity of retrograded short-range starch double helices, while the relationship was opposite after adding NaCl. These results help a better understanding of the complex relationship between starch structure and physicochemical property.

Genome-Wide Analysis of the Auxin/Indoleacetic Acid Gene Family and Response to Indole-3-Acetic Acid Stress in Tartary Buckwheat (Fagopyrum tataricum).

Auxin/indoleacetic acid (Aux/IAA) family genes respond to the hormone auxin, which have been implicated in the regulation of multiple biological processes. In this study, all 25 Aux/IAA family genes were identified in Tartary buckwheat (Fagopyrum tataricum) by a reiterative database search and manual annotation. Our study provided comprehensive information of Aux/IAA family genes in buckwheat, including gene structures, chromosome locations, phylogenetic relationships, and expression patterns. Aux/IAA family genes were nonuniformly distributed in the buckwheat chromosomes and divided into seven groups by phylogenetic analysis. Aux/IAA family genes maintained a certain correlation and a certain species-specificity through evolutionary analysis with Arabidopsis and other grain crops. In addition, all Aux/IAA genes showed a complex response pattern under treatment of indole-3-acetic acid (IAA). These results provide valuable reference information for dissecting function and molecular mechanism of Aux/IAA family genes in buckwheat.

The Salvia miltiorrhiza NAC transcription factor SmNAC1 enhances zinc content in transgenic Arabidopsis.

NAC transcription factors play important roles in plant biological processes, including plant development, environmental stress responses and element enrichment. A novel NAC transcription factor gene, designated SmNAC1, was isolated from Salvia miltiorrhiza. SmNAC1 was localized in the nucleus in onion protoplasts and exhibited transcriptional activation activities in yeast. In addition, the SmNAC1 protein could specifically bind to the cis-elements of the NAC proteins. SmNAC1 was expressed at a higher level in the leaves of S. miltiorrhiza, indicating that SmNAC1 might be involved in the transportation of zinc. To examine the function of SmNAC1, transgenic Arabidopsis plants overexpressing SmNAC1 were generated. Zinc content assays in the transgenic plants demonstrated that overexpressed SmNAC1 plants had enhanced tolerance to high zinc concentrations, and zinc was enriched in the shoot tissues. Our results demonstrate that SmNAC1 plays important roles in the response to zinc stress. Zinc was mainly enriched in the leaves of S. miltiorrhiza and the shoot tissues of transgenic Arabidopsis plants. SmNAC1 might participate in zinc transportation from the roots to the shoots, that constitutes a useful gene for improving zinc content in plants.

QTL Mapping of Kernel Number-Related Traits and Validation of One Major QTL for Ear Length in Maize.

The kernel number is a grain yield component and an important maize breeding goal. Ear length, kernel number per row and ear row number are highly correlated with the kernel number per ear, which eventually determines the ear weight and grain yield. In this study, two sets of F2:3 families developed from two bi-parental crosses sharing one inbred line were used to identify quantitative trait loci (QTL) for four kernel number-related traits: ear length, kernel number per row, ear row number and ear weight. A total of 39 QTLs for the four traits were identified in the two populations. The phenotypic variance explained by a single QTL ranged from 0.4% to 29.5%. Additionally, 14 overlapping QTLs formed 5 QTL clusters on chromosomes 1, 4, 5, 7, and 10. Intriguingly, six QTLs for ear length and kernel number per row overlapped in a region on chromosome 1. This region was designated qEL1.10 and was validated as being simultaneously responsible for ear length, kernel number per row and ear weight in a near isogenic line-derived population, suggesting that qEL1.10 was a pleiotropic QTL with large effects. Furthermore, the performance of hybrids generated by crossing 6 elite inbred lines with two near isogenic lines at qEL1.10 showed the breeding value of qEL1.10 for the improvement of the kernel number and grain yield of maize hybrids. This study provides a basis for further fine mapping, molecular marker-aided breeding and functional studies of kernel number-related traits in maize.

Genetic architecture of maize kernel row number and whole genome prediction.

KEY MESSAGE: Maize kernel row number might be dominated by a set of large additive or partially dominant loci and several small dominant loci and can be accurately predicted by fewer than 300 top KRN-associated SNPs. Kernel row number (KRN) is an important yield component in maize and directly affects grain yield. In this study, we combined linkage and association mapping to uncover the genetic architecture of maize KRN and to evaluate the phenotypic predictability using these detected loci. A genome-wide association study revealed 31 associated single nucleotide polymorphisms (SNPs) representing 17 genomic loci with an effect in at least one of five individual environments and the best linear unbiased prediction (BLUP) over all environments. Linkage mapping in three F2:3 populations identified 33 KRN quantitative trait loci (QTLs) representing 21 QTLs common to several population/environments. The majority of these common QTLs that displayed a large effect were additive or partially dominant. We found 70% KRN-associated genomic loci were mapped in KRN QTLs identified in this study, KRN-associated SNP hotspots detected in NAM population and/or previous identified KRN QTL hotspots. Furthermore, the KRN of inbred lines and hybrids could be predicted by the additive effect of the SNPs, which was estimated using inbred lines as a training set. The prediction accuracy using the top KRN-associated tag SNPs was obviously higher than that of the randomly selected SNPs, and approximately 300 top KRN-associated tag SNPs were sufficient for predicting the KRN of the inbred lines and hybrids. The results suggest that the KRN-associated loci and QTLs that were detected in this study show great potential for improving the KRN with genomic selection in maize breeding.

ZmGA3ox2, a candidate gene for a major QTL, qPH3.1, for plant height in maize.

Maize plant height is closely associated with biomass, lodging resistance and grain yield. Determining the genetic basis of plant height by characterizing and cloning plant height genes will guide the genetic improvement of crops. In this study, a quantitative trait locus (QTL) for plant height, qPH3.1, was identified on chromosome 3 using populations derived from a cross between Zong3 and its chromosome segment substitution line, SL15. The plant height of the two lines was obviously different, and application of exogenous gibberellin A(3) removed this difference. QTL mapping placed qPH3.1 within a 4.0 cM interval, explaining 32.3% of the phenotypic variance. Furthermore, eight homozygous segmental isolines (SILs) developed from two larger F(2) populations further narrowed down qPH3.1 to within a 12.6 kb interval. ZmGA3ox2, an ortholog of OsGA3ox2, which encodes a GA3 ß-hydroxylase, was positionally cloned. Association mapping identified two polymorphisms in ZmGA3ox2 that were significantly associated with plant height across two experiments. Quantitative RT-PCR showed that SL15 had higher ZmGA3ox2 expression relative to Zong3. The resultant higher GA(1) accumulation led to longer internodes in SL15 because of increased cell lengths. Moreover, a large deletion in the coding region of ZmGA3ox2 is responsible for the dwarf mutant d1-6016. The successfully isolated qPH3.1 enriches our knowledge on the genetic basis of plant height in maize, and provides an opportunity for improvement of plant architecture in maize breeding.