The Specific Features of Anthocyanin Biosynthesis Regulation in Wheat
Abstract Anthocyanins are flavonoid pigments important for plant adaptation under biotic and abiotic stress conditions. In bread wheat (Triticum aestivum L.), purple pigmentation caused by anthocyanins can be present on leaves, culm, auricles, glumes, grains, coleoptile, and anthers. Since the first mentions on expression of purple color traits in wheat, the studies into inheritance of these characters have made big steps toward revealing molecular-genetic mechanisms of anthocyanin pigment biosynthesis and its regulation in wheat. Most of the structural genes, encoding enzymes of the biosynthesis, have been cloned and localized in wheat genome. The genetic mapping data suggest that different pigmentation patterns in wheat are determined by genetic loci, distinct from the enzyme encoding loci. The data on functional role of the genes underpinning phenotypic variation together with results of inter-genera comparative mapping suggest these genes to encode transcriptional activators of the anthocyanin biosynthesis structural genes. Here, a brief review is provided of recent findings in the genetic regulation of anthocyanin biosynthesis in wheat.
Keywords Purple pigmentation • Comparative mapping • Regulatory genes • Structural genes • Transcription analysis • Triticum aestivum L
Anthocyanin pigmentation of different parts of plants is related with their adaptation to environment stress conditions (reviewed by Chalker-Scott 1999; Khlestkina 2013a). In addition, anthocyanins are important for human health maintenance, preventing cardiovascular diseases, carcinogenesis, inflammation and many others human pathological states (Lila 2004). All these findings stimulated intensive investigations of different aspects of anthocyanin biosynthesis in plants, and nowadays, it is considered to be one of the best characterized secondary metabolite pathways (Winkel-Shirley 2001). Identification of the anthocyanin biosynthesis regulatory and structural genes in the model plant species (maize, Arabidopsis, snapdragon, and petunia) (Mol et al. 1998) facilitates homology-based cloning of their orthologues in cultivated species with complex genomes, such as bread wheat (Triticum aestivum L., 2n = 6x = 42).
In wheat, purple colour of coleoptile, culm and anthers is reportedly related with resistance to bunt (Bogdanova et al. 2002). Comparative analysis of wheat nearisogenic lines differing by anthocyanin content in the coleoptile and pericarp showed higher drought tolerance of intensely colored seedlings (Tereshchenko et al. 2012a). The relationship between accumulation of anthocyanins in wheat coleoptiles and cold treatment has been shown (Gordeeva et al. 2013). Furthermore, the purple-grained NILs had better viability after accelerated ageing compared to the recurrent parent lacking anthocyanins (Gordeeva and Khlestkina 2013). The knowledge about specific features of anthocyanin biosynthesis regulation in wheat can be useful for improvement of its adaptation to biotic and abiotic stress conditions.