Identification of regulatory factors promoting embryogenic callus formation in barley through transcriptome analysis.

BACKGROUND: Barley is known to be recalcitrant to tissue culture, which hinders genetic transformation and its biotechnological application. To date, the ideal explant for transformation remains limited to immature embryos; the mechanism underlying embryonic callus formation is elusive. RESULTS: This study aimed to uncover the different transcription regulation pathways between calli formed from immature (IME) and mature (ME) embryos through transcriptome sequencing. We showed that incubation of embryos in an auxin-rich medium caused dramatic changes in gene expression profiles within 48 h. Overall, 9330 and 11,318 differentially expressed genes (DEGs) were found in the IME and ME systems, respectively. 3880 DEGs were found to be specific to IME_0h/IME_48h, and protein phosphorylation, regulation of transcription, and oxidative-reduction processes were the most common gene ontology categories of this group. Twenty-three IAA, fourteen ARF, eight SAUR, three YUC, and four PIN genes were found to be differentially expressed during callus formation. The effect of callus-inducing medium (CIM) on IAA genes was broader in the IME system than in the ME system, indicating that auxin response participates in regulating cell reprogramming during callus formation. BBM, LEC1, and PLT2 exhibited a significant increase in expression levels in the IME system but were not activated in the ME system. WUS showed a more substantial growth trend in the IME system than in the ME system, suggesting that these embryonic, shoot, and root meristem genes play crucial roles in determining the acquisition of competency. Moreover, epigenetic regulators, including SUVH3A, SUVH2A, and HDA19B/703, exhibited differential expression patterns between the two induction systems, indicating that epigenetic reprogramming might contribute to gene expression activation/suppression in this process. Furthermore, we examined the effect of ectopic expression of HvBBM and HvWUS on Agrobacterium-mediated barley transformation. The transformation efficiency in the group expressing the PLTPpro:HvBBM + Axig1pro:HvWUS construct was increased by three times that in the control (empty vector) because of enhanced plant regeneration capacity. CONCLUSIONS: We identified some regulatory factors that might contribute to the differential responses of the two explants to callus induction and provide a promising strategy to improve transformation efficiency in barley.

Manipulating a Single Transcription Factor, Ant1, Promotes Anthocyanin Accumulation in Barley Grains.

Barley has abundant anthocyanin-rich accessions, which renders it an ideal model to investigate the regulatory mechanism of anthocyanin biosynthesis. This study functionally characterized two transcription factors: Ant1 and Ant2. Sequence alignment showed that the coding sequences of Ant1 and Ant2 are conserved among 11 colored hulless barley and noncolored barley varieties. The expression profiles of Ant1 and Ant2 were divergent between species, and significantly higher expression was found in two colored Qingke accessions. The co-expression of Ant1 and Ant2 resulted in purple pigmentation in transient transformation systems via the promotion of the transcription of four structural genes. Ant1 interacted with Ant2, and overexpression of Ant1 activated the transcription of Ant2. Moreover, overexpression of Ant1 led to anthocyanin accumulation in the pericarp and aleurone layer of transgenic barley grains. Overall, our results suggest that anthocyanin-enriched barley grains can be produced by manipulating Ant1 expression.

Whole Grain Qingke Attenuates High-Fat Diet-Induced Obesity in Mice With Alterations in Gut Microbiota and Metabolite Profile.

Whole grain Qingke (WGQK) displays anti-obesity and lipid-lowering properties; however, the underlying mechanism remains elusive. This study investigated the alteration of gut microbiota composition and metabolite profile induced by WGQK intervention in mice through the integration of 16S ribosomal RNA (rRNA) sequencing and an untargeted metabolomics study. C57BL/6J male mice were fed a normal control diet (NC), high-fat diet (HFD), and HFD plus 30% WGQK (HFD+QK) for 16 weeks. The WGQK intervention decreased body weight gain, glucose tolerance, and serum lipid levels, and alleviated liver function damage induced by HFD. Moreover, WGQK changed gut microbiota composition and enriched specific genera such as Akkermansia, Bifidobacterium, and Lactobacillus. Fecal metabolomics analysis indicated that WGQK enhanced the abundance of tryptophan metabolism-related metabolites (indole, 3-indoleacetic acid, indole acetic acid (IAA), 5-hydroxyindole-3-acetic acid), histidine metabolism-related metabolites (histamine), and some unsaturated fatty acids (oleic acid, 9,10-dihydroxy-12Z-octadecenoic acid, and alpha-linolenic acid). Spearman correlation analysis revealed that these metabolites were negatively correlated with obesity-related parameters and positively correlated with the gut genera enriched by WGQK. Moreover, WGQK promoted the expression of Cholesterol 7α-hydroxylase (CYP7A1) responsible for primary bile acids production, accompanied by a decline in intestinal FXR-FGF15 expression levels. The transcript levels of two genes associated with lipogenesis, such as lipid fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) were also decreased in the HFD+QK group. Overall, our results suggest interactions between gut microbial shifts and host amino acid/lipid metabolism, and shed light on the mechanisms underlying the anti-obesity effect of WGQK.