Upregulation of CBF/DREB1 and cold tolerance in artificial seeds of cauliflower (Brassica oleracea var. botrytis)

Abstract

An effective protocol for cauliflower micropropagation and artificial seed production was optimised by (Rihan et al. 2012a; Rihan et al. 2012b; Rihan et al. 2011b; Rihan et al. 2012c). However, in order to be a viable alternative to traditional seeds, cauliflower artificial seeds need to show a high capacity to withstand abiotic stresses such as cold and desiccation. Therefore, in order to increase cauliflower abiotic stress tolerance, the effect of cold acclimation and drought on the cold tolerance of both cauliflower microshoots and mature plants were investigated. Moreover, the effect of cold and drought treatments on the induction of CBF/DREB1 gene regulation was tested. Both cold acclimation and drought improved the cold tolerance in both cauliflower microshoots and mature plants. However, whilst cold acclimation up-regulated CBF/DREB1 in cauliflower mature plants and microshoots, drought had the capacity only to up-regulate this gene in mature plants. Therefore, the high effect of cauliflower developmental stage on the CBF/DREB1 regulation was confirmed. Moreover, a small reduction in soil moisture had the capacity to upregulated this gene in mature cauliflower plants. The results presented in this study have an important role in the improvement of cauliflower micropropagation and the effectiveness of the artificial seed production protocol. Furthermore, the results contribute to an understanding of the cold tolerance mechanism in Brassica oleraceae var botrytis.

Physiological and Molecular Mechanism Involved in Cold Stress Tolerance in Plants

“…AtHAP5A and AtXTH21 overexpressing plants were more tolerant of freezing stress but less susceptible to ABA than WT plants [61]. Moreover, ABA also plays an important role in the acclimation process and can induce COR gene expression [26]. Some genes in Pyrus ussuriensis also collaborate with ABA, Gibberellin, and Ethylene to up-regulate genes [35].…”

“…The AP2/ERF family is one of the largest TF families in plants and is characterized by having a minimum of one AP2 DNA-binding domain [25]. CBFs activate the expression of COR genes via binding to cis-element in the promoter of COR genes (CRT: TGGCCCGAC) (Figure 1) [23,26]. In addition to LT stress, CBFs also play important roles in other abiotic stresses [7,26,27].…”

“…CBFs activate the expression of COR genes via binding to cis-element in the promoter of COR genes (CRT: TGGCCCGAC) (Figure 1) [23,26]. In addition to LT stress, CBFs also play important roles in other abiotic stresses [7,26,27]. Some of the cold-responsive genes have an ABA responsive element and dehydration responsive element in their promoter regions [28].…”

“…Expression of those genes is increased by 50 Gy of carbon ion beam irradiation for 6 h and 12 h at 4 • C. Nonetheless, in Arabidopsis, carbon ion beam irradiation of 50 Gy increases the content of AsA and GSH, which play important roles in alleviating ROS generation and oxidative stress under cold stress [22]. The level of soil moisture and stomatal conductivity has been determined by Rihan et al [26]; these two factors can up-regulate the CBF/DREB1 gene in cauliflower (Brassica oleracea var. botrytis).…”

Multiple Regulatory Networks Are Activated during Cold Stress in Medicago sativa L.

“…The CBF signaling pathway can increase freezing tolerance, which was demonstrated to exist in numerous plants, such as thale cress ( Arabidopsis thaliana ) [ 17 ], cauliflower ( Brassica oleracea var. botrytis ) [ 18 ], and peach ( Prunus persica ) [ 19 ]. A recent report suggested that CBFs may play an important role in the regulation of freezing tolerance in alfalfa, based on the expression of C-repeat binding factor-like (CBFl) genes [ 20 ].…”