Sorghum (Sorghum bicolor) is the fifth most important cereal crop in the world. It is an annual C4 crop due to its high biomass and wide usage, and has a strong resistance to stress. Obviously, there are many benefits of planting sorghum on marginal soils such as saline-alkali land. Although it is known that abscisic acid (ABA) is involved in plant abiotic stress responses, there are few reports on sorghum. Here, we obtained RNA-seq data, which showed gene expression at the genome-wide level under saline-alkali stress. The genes related to ABA biosynthesis, catabolism, and signaling were identified and analyzed. Meanwhile, their amino acid sequences were intermingled with rice genes to form several distinct orthologous and paralogous groups. ABA-related differentially expressed genes under saline-alkali stress were identified, and family members involved in ABA signaling were hypothesized based on the expression levels and homologous genes in rice. Furthermore, the ABA signaling pathway in Sorghum bicolor was understood better by interaction analysis. These findings present a comprehensive overview of the genes regulating ABA biosynthesis, catabolism, and signaling in Sorghum bicolor under saline-alkali stress, and provide a foundation for future research regarding their biological roles in sorghum stress tolerance.

Key message: HanMYB1 was found to play positive roles in the modulation of anthocyanins metabolism based on the integrative analysis of different color cultivars and the related molecular genetic analyses. As a high value ornamental and edible crop with various colors, sunflowers (Helianthus annuus L.) provide an ideal system to understand the formation of flower color. Anthocyanins are major pigments in higher plants, which is associated with development of flower colors and ability of oxidation resistance. Here, we performed an integrative analysis of the transcriptome and flavonoid metabolome in five sunflower cultivars with different flower colors. According to differentially expressed genes and differentially accumulated flavonoids, these cultivars could be grouped into yellow and red. The results showed that more anthocyanins were accumulated in the red group flowers, especially the chrysanthemin. Some anthocyanins biosynthesis-related genes like UFGT (UDP-glycose flavonoid glycosyltransferase) also expressed more in the red group flowers. A MYB transcriptional factor, HanMYB1, was found to play vital positive roles in the modulation of anthocyanins metabolism by the integrative analysis. Overexpressed HanMYB1 in tobacco could deepen the flower color, increase the accumulation of anthocyanins and directly active the express of UFGT genes. Our findings indicated that the MYB transcriptional factors provide new insight into the dynamic regulation of the anthocyanin biosynthesis in facilitating sunflower color formation and anthocyanin accumulation.

Pectin is an abundant polysaccharide with essential roles in various biological processes. Despite considerable advances in understanding the regulatory mechanisms of pectin biosynthesis, the influence of phytohormones on this process remains unclear. Here we report that gibberellins (GA) promotes pectin biosynthesis in Arabidopsis. The DELLA proteins, as GA signaling repressors, interact with TRANSPARENT TESTA GLABRA2 (TTG2) and components of the MYB-bHLH-WD40 (MBW) complex, the key regulators of pectin biosynthesis, to repress their transcriptional regulatory activities. Furthermore, the MBW proteins and TTG2 physically interact and synergistically activate the downstream target GLABRA2, whereas this interaction and collaboration are competitively attenuated by DELLAs. Genetic analyses validate that GA-mediated pectin biosynthesis relies on functional TTG2 and MBW proteins. Moreover, the pectin biosynthesis mediated by the GA-DELLA-MBW-TTG2 module contributes to GA-regulated seedling growth. Our findings reveal the significance of the GA-DELLA-MBW-TTG2 signaling cascade in the regulation of pectin biosynthesis and plant development.