Identification and functional characterization of the BBX24 promoter and gene from chrysanthemum in Arabidopsis

Abstract

The B-box (BBX) family is a subgroup of zinc finger transcription factors that regulate flowering time, light-regulated morphogenesis, and abiotic stress in Arabidopsis. Overexpression of CmBBX24, a zinc finger transcription factor gene in chrysanthemum, results in abiotic stress tolerance. We have investigated and characterized the promoter of CmBBX24, isolating a 2.7-kb CmBBX24 promoter sequence and annotating a number of abiotic stress-related cis-regulatory elements, such as DRE, MYB, MYC, as well as cis-elements which respond to plant hormones, such as GARE, ABRE, and CARE. We also observed a number of cis-elements related to light, such as TBOX and GBOX, and some tissue-specific cis-elements, such as those for guard cells (TAAAG). Expression of the CmBBX24 promoter produced a clear response in leaves and a lower response in roots, based on β-glucuronidase histochemical staining and fluorometric analysis. The CmBBX24 promoter was induced by abiotic stresses (mannitol, cold temperature), hormones (gibberellic acid, abscisic acid), and different light treatments (white, blue, red); activation was measured by fluorometric analysis in the leaves and roots. The deletion of fragments from the 5'-end of the promoter led to different responses under various stress conditions. Some CmBBX24 promoter segments were found to be more important than others for regulating all stresses, while other segments were relatively more specific to stress type. D0-, D1-, D2-, D3-, and D4-proCmBBX24::CmBBX24 transgenic Arabidopsis lines developed for further study were found to be more tolerant to the low temperature and drought stresses than the controls. We therefore speculate that CmBBX24 is of prime importance in the regulation of abiotic stress in Arabidopsis and that the CmBBX24 promoter is inductive in abiotic stress conditions. Consequently, we suggest that CmBBX24 is a potential candidate for the use in breeding programs of important ornamental plants.

Isolation and characterization of a promoter responsive to salt, osmotic and dehydration stresses in soybean

“…Other authors have also shown the importance of distal promoter regions in stress-associated responses (Behnam et al , 2013; Imtiaz et al , 2015). For example, the 3.0-kb AtNCED3 promoter sequence was able to drive uidA expression in response to dehydration, while the 1.5-kb AtNCED3 promoter region was not functional (Tan et al , 2003; Behnam et al , 2013).…”

“…In addition, other constructs containing pGAL -2kb deletions may also be active as drought-responsive, as efficient as the entire sequence. Imtiaz et al (2015) showed that the deletion of the 1,162-bp fragment between −2,552 (full promoter) and −1,390 significantly reduced promoter activity in leaves and roots, while no significant decrease in promoter activity was observed with further deletions from −1,390 to −780, −780 to 600 and −600 to −480. Thus, further analyses will aid in better characterizing the use of the pGAL -2kb promoter as a new drought stress-responsive promoter.…”

“…For example, the 3.0-kb AtNCED3 promoter sequence was able to drive uidA expression in response to dehydration, while the 1.5-kb AtNCED3 promoter region was not functional (Tan et al , 2003; Behnam et al , 2013). Imtiaz et al (2015) showed that the 2.7-kb CmBBX24 promoter sequence of Chrysanthemum has activity in Arabidopsis transgenic plants under drought and salt stress, but the deletion of fragments from the promoter's distal end led to a lower promoter activity under drought stress. When compared to the pGAL -1kb promoter sequence, pGAL -2kb has four additional cis -motifs previously associated with the response to drought stress, including one ABRE, one MYCATERD1, one GBOX and one DRE (Table 1).…”

“…Indeed, the control of the expression of drought-tolerant genes by stress-responsive and/or tissue-specific promoters has been used as alternative for the elimination of negative effect of constitutive gene expression driven by the CaMV35S promoter (Chan Ju et al , 2012; Banerjee et al , 2013; Yan et al , 2015). Recently, stress-responsive promoters, such as the PeNAC1 (Wang et al , 2016), ZmGAPP (Hou et al , 2016), BBX24 (Imtiaz et al. , 2015), and GmNCED 1 and GmMYB363P promoters (Li et al.…”

Characterization of the chemical composition of white chrysanthemum flowers of Hangzhou by using high‐performance ion trap mass spectrometry

“…White chrysanthemum flowers of Hangzhou (WCF‐HZ; Hang Baiju in Chinese) are one of the most popular traditional medicines and food in China. WCF‐HZ can dispel wind and heat, calm the liver, brighten the eyes, and clear heat toxicity . As previously reported, WCF‐HZ mainly contains significant amounts of flavonoids, volatile oils, and hydroxycinnamoylquinic acids, which are considered biologically active components ; WCF‐HZ is used as an important food supplement or herbal tea for antichronic, inflammatory, antihypertensive, abirritative, antispasmodic, antihepatitis B virus, and immunological enhancement activities .…”