Factors of wheat frost hardiness – ice recrystallization inhibitor proteins

For winter wheat, winter hardiness is one of the complex traits that determine the successful cultivation of this crop, and the responsible genes are recognized as highly significant for breeding work. The accumulation of proteins that prevent ice recrystallization (ice recrystallization inhibition proteins, IRIP) correlates with the survival of winter wheat, which indicates the importance of taking this trait into account when obtaining more frost-resistant varieties. The importance of IRIPs is determined by their ability to integrate into growing ice crystals, which limits the formation of large ice conglomerates in the tissues of winter plants. Wheat IRIPs, which accumulate mainly in the apoplast of leaves and in the crowns during cold acclimation, are characterized by a typical duality of structural organization that determines both the manifestation of IRI activity and anti-pathogenic properties. The wheat IRIP molecule contains at the C-terminus a conserved NxVx(x)G fragment that repeats several times, forming a β-helix responsible for binding to the ice surface; at the N-terminus, there is an LRR sequence typical of pathogen-activated kinases, as well as a guiding signal peptide. The wheat genome contains up to eleven IRI genes. The TaIRI gene promoter contains typical basic cis-activating elements and some elements that respond to abiotic stress and hormones. Isoforms of proteins responsible for protecting against pathogens (pathogenesis related proteins, PRP), which accumulate in winter wheat during cold acclimation, also have IRI activity. The expression of the IRIP and PRP genes positively correlates with the cold resistance of winter wheat plants. According to modern data, the regulation of the IRIP genes and cold-activated PRP genes is ABA-independent, but depends on the presence of jasmonic acid and on some proteomic transcription factors. The review provides examples of the practical use of isolated winter wheat IRIPs. The issue of the factors regulating the activity of the IRIP genes and cold-activated PRPs is the least developed to date. The association of these proteins with the winter hardiness of wheat indicates the prospects for their further study.