The Characterization of R2R3-MYB Genes in Ammopiptanthus nanus Uncovers That the miR858-AnaMYB87 Module Mediates the Accumulation of Anthocyanin under Osmotic Stress.

R2R3-MYB transcription factors (TFs) participate in the modulation of plant development, secondary metabolism, and responses to environmental stresses. Ammopiptanthus nanus, a leguminous dryland shrub, tolerates a high degree of environmental stress, including drought and low-temperature stress. The systematic identification, structural analysis, evolutionary analysis, and gene profiling of R2R3-MYB TFs under cold and osmotic stress in A. nanus were performed. Up to 137 R2R3-MYB TFs were identified and clustered into nine clades, with most A. nanus R2R3-MYB members belonging to clade VIII. Tandem and segmental duplication events drove the expansion of the A. nanus R2R3-MYB family. Expression profiling revealed that multiple R2R3-MYB genes significantly changed under osmotic and cold stress conditions. MiR858 and miR159 targeted 88 R2R3-MYB genes. AnaMYB87, an miR858-targeted clade VIII R2R3-MYB TF, was up-regulated under both osmotic and cold stress. A transient expression assay in apples showed that the overexpression of AnaMYB87 promoted anthocyanin accumulation. A luciferase reporter assay in tobacco demonstrated that AnaMYB87 positively affected the transactivation of the dihydroflavonol reductase gene, indicating that the miR858-MYB87 module mediates anthocyanin accumulation under osmotic stress by regulating the dihydroflavonol reductase gene in A. nanus. This study provides new data to understand the roles of R2R3-MYB in plant stress responses.

The complete chloroplast genome of Thermopsis lanceolata: genome structure and its phylogenetic relationships within the family Fabaceae.

Thermopsis lanceolata R. Br. belongs to the genus Thermopsis, Fabaceae. The alkaloids of T. lanceolata have anti-cancer, anti-heart rate disorders and other pharmacological effects. To explore the chloroplast genome of T. lanceolata and its phylogenetic relationship, a complete chloroplast genome of T. lanceolata was sequenced and annotated, and a phylogenetic tree was constructed. The complete chloroplast genome of T. lanceolata is a circular molecule of 151,526 bp, consisting of a large single copy (LSC) region of 83,780 bp, a small single copy (SSC) region of 15,566 bp, and a pair of inverted repeats (IRa and IRb) of 26,090 bp. The chloroplast genome of T. lanceolata contained 130 genes, including 85 protein-coding genes, 37 transfer RNA genes, and 8 ribosomal RNA genes. Phylogenetic analysis revealed a close relationship between T. lanceolata and T. turkestanica.