Transgenic barley lines prove the involvement of TaCBF14 and TaCBF15 in the cold acclimation process and in frost tolerance

Abstract

The enhancement of winter hardiness is one of the most important tasks facing breeders of winter cereals. For this reason, the examination of those regulatory genes involved in the cold acclimation processes is of central importance. The aim of the present work was the functional analysis of two wheat CBF transcription factors, namely TaCBF14 and TaCBF15, shown by previous experiments to play a role in the development of frost tolerance. These genes were isolated from winter wheat and then transformed into spring barley, after which the effect of the transgenes on low temperature stress tolerance was examined. Two different types of frost tests were applied; plants were hardened at low temperature before freezing, or plants were subjected to frost without a hardening period. The analysis showed that TaCBF14 and TaCBF15 transgenes improve the frost tolerance to such an extent that the transgenic lines were able to survive freezing temperatures several degrees lower than that which proved lethal for the wild-type spring barley. After freezing, lower ion leakage was measured in transgenic leaves, showing that these plants were less damaged by the frost. Additionally, a higher Fv/Fm parameter was determined, indicating that photosystem II worked more efficiently in the transgenics. Gene expression studies showed that HvCOR14b, HvDHN5, and HvDHN8 genes were up-regulated by TaCBF14 and TaCBF15. Beyond that, transgenic lines exhibited moderate retarded development, slower growth, and minor late flowering compared with the wild type, with enhanced transcript level of the gibberellin catabolic HvGA2ox5 gene.

Hv-CBF2A overexpression in barley accelerates COR gene transcript accumulation and acquisition of freezing tolerance during cold acclimation

“…As was the case with our Hv-CBF2A overexpressing lines, most of the Ta-CBF14 and Ta-CBF15 overexpressing lines exhibited growth stunting and delayed development relative to 'Golden Promise' (Soltész et al 2013). In plants that were grown in wooden boxes and had been cold acclimated, increases in plant survival following freezing were detected in independent lines overexpressing each of the two CBFs (Soltész et al 2013). Under non-acclimating conditions two of eleven Ta-CBF14 and Ta-CBF15 overexpressing lines exhibited survival percentages that were significantly greater than that of 'Golden Promise' (Soltész et al 2013).…”

“…In some aspects the findings of the two studies are similar, and in other aspects the findings seemingly are different. As was the case with our Hv-CBF2A overexpressing lines, most of the Ta-CBF14 and Ta-CBF15 overexpressing lines exhibited growth stunting and delayed development relative to 'Golden Promise' (Soltész et al 2013). In plants that were grown in wooden boxes and had been cold acclimated, increases in plant survival following freezing were detected in independent lines overexpressing each of the two CBFs (Soltész et al 2013).…”

“…During the revision of this manuscript Soltész and colleagues published findings from their work in which they overexpressed wheat CBF14 and CBF15 in 'Golden Promise' barley (Soltész et al 2013). Ta-CBF14, like Hv-CBF2, is an HvCBF4/CBFIV CBF whereas Ta-CBF15 is an HvCBF3/CBFIII CBF.…”

Advances in physiological and molecular aspects of plant cold tolerance

“…However, MaMYC2 interact with MaICE1, activating the cold signaling of the CBF-dependent pathway. Soltész et al (2013) reported that TaCBF14 and TaCBF15 play an essential role in cold tolerance of wheat. Moreover, they reported that these genes improved the cold tolerance of transgenic plants by several degrees lower than control plants.…”

C-Repeat Binding Factor and Dehydrin Genes are Induced Co-Ordinately in Drought Tolerance Response of Wheat Cultivars

“…Cbf14 and Cbf15 genes of wheat were first identified in Triticum monococcum L. and mapped to a major locus determining frost tolerance in this species (Miller et al, 2006). Cbf14 and Cbf15 of Triticum aestivum were functionally tested by transformation of barley, proving the role of these genes in freezing tolerance (Soltész et al, 2013). Along with alleviation of consequences of freezing stress, transcriptional activation of some dehydrin genes was also noted in the transgenic barley lines.…”