A Novel bHLH Transcription Factor Involved in Regulating Anthocyanin Biosynthesis in Chrysanthemums (Chrysanthemum morifolium Ramat.)

Abstract

Chrysanthemums (Chrysanthemum morifolium Ramat.) exhibit a variety of flower colors due to their differing abilities to accumulate anthocyanins. One MYB member, CmMYB6, has been verified as a transcription regulator of chrysanthemum genes involved in anthocyanin biosynthesis; however, the co-regulators for CmMYB6 remain unclear in chrysanthemum. Here, the expression pattern of CmbHLH2, which is clustered in the IIIf bHLH subgroup, was shown to be positively correlated with the anthocyanin content of cultivars with red, pink and yellow flower colors, respectively. CmbHLH2 significantly upregulated the CmDFR promoter and triggered anthocyanin accumulation when co-expressed with CmMYB6. Yeast one-hybrid analyses indicated that CmbHLH2 was able to bind directly to the CmDFR promoter. Moreover, yeast two-hybrid assays indicated protein-protein interaction between CmbHLH2 and CmMYB6. These results suggest that CmbHLH2 is the essential partner for CmMYB6 in regulating anthocyanin biosynthesis in chrysanthemum.

A Radish Basic Helix-Loop-Helix Transcription Factor, RsTT8 Acts a Positive Regulator for Anthocyanin Biosynthesis

“…The first bHLH TFs found to regulate anthocyanin biosynthesis were identified in maize and were designated as Red1 and Booster1 (Chandler et al, 1989 ). Subsequent work identified a number of additional bHLH TFs that regulate flavonoid biosynthesis, including AN1 and JAF13 in petunia ( Petunia hybrida ) (Quattrocchio et al, 1998 ; Spelt et al, 2000 ), TT8 and GLABRA3 (GL3) in Arabidopsis (Nesi et al, 2000 ; Feyissa et al, 2009 ), StbHLH1 and StJAF13 in potato ( Solanum tuberosum ) (Payyavula et al, 2013 ; D'amelia et al, 2014 ), CmbHLH2 in chrysanthemum ( Chrysanthemum morifolium ) (Xiang et al, 2015 ), MdbHLH3 and MdbHLH33 in apple (Espley et al, 2007 ), and FhTT8 and FhGL3 in freesia ( Freesia hybrida ) (Li et al, 2016 ). Many of these bHLH TFs have been shown to regulate physiological and morphological events such as flavonoid biosynthesis and the formation of root hairs and trichomes (Grotewold, 2006 ).…”

Metabolite and transcriptome analyses provide new insights into the generation of the blue supramolecular pigment in cornflower

“…When co-infiltrated with CcMYB6-1 and CcbHLH1, both the trans-activity of CcF3H and CcDFR promoters as well as the anthocyanin content accumulation were significantly enhanced in tobacco leaves (Fig. 5), similar to the cases in chrysanthemum and grape hyacinth [34,35]. Subgroup 4 of Arabidopsis R2R3 MYBs encodes transcriptional repressors, and AtMYB4 was identified as a repressor in the regulation of phenylpropanoid pathway gene expression [21,36].…”

Tree rings provide a new class of phenotypes for genetic associations that foster insights into adaptation of conifers to climate change

“…Comparing the populations' responses to climate (type B and type C traits) in the common garden revealed existing genetic variation for tolerance to freeze and drought. The positive influence of a warm autumn during the year preceding ring formation (CS BAI -Temp.Oct (tÀ1) ) was stronger for populations from southernmost provenances and significantly increased with MAT p Anthocyanin biosynthesis, cell proliferation and differentiation (Yamada et al, 2011;Xiang et al, 2015) Diverse abiotic stresses (Ji et al, 2016) B, C N-040 2_4107_01 S Photosynthetic electron transfer (Ishihara et al, 2007) Diverse abiotic stresses in herbaceous plants (Gururani et al, 2015) Known functions and responses to abiotic stresses of homologous genes in other plant species are reported in the two right-hand columns of the New Phytologist (Fig. 4a,b).…”