Mapping of barley homologs to genes that regulate low temperature tolerance in Arabidopsis

Abstract

We investigated the allelic nature and map locations of Hordeum vulgare (barley) homologs to three classes of Arabidopsis low temperature (LT) regulatory genes-CBFs, ICE1, and ZAT12-to determine if there were any candidates for winterhardiness-related quantitative trait loci (QTL). We phenotyped the Dicktoo x Morex (DxM) mapping population under controlled freezing conditions and in addition to the previously reported 5H-L Fr-H1 QTL, observed three additional LT tolerance QTLs on 1H-L, 4H-S, and 4H-L. We identified and assigned either linkage map or chromosome locations to 1 ICE1 homolog, 2 ZAT12 homologs, and 17 of 20 CBF homologs. Twelve of the CBF genes were located on 5H-L and the 11 with assigned linkage map positions formed 2 tandem clusters on 5H-L. A subset of these CBF genes was confirmed to be physically linked, validating the map position clustering. The tandem CBF clusters are not candidates for the DxM LT tolerance Fr-H1 QTL, as they are approximately 30 cM distal to the QTL peak. No LT tolerance QTL was detected in conjunction with the CBF gene clusters in Dicktoo x Morex. However, comparative mapping using common markers and BIN positions established the CBF clusters are coincident with reported Triticeae LT tolerance and COR gene accumulation QTLs and suggest one or more of the CBF genes may be candidates for Fr-H2 in some germplasm combinations. These results suggest members of the CBF gene family may function as components of winter-hardiness in the Triticeae and underscore both the importance of extending results from model systems to economically important crop species and in viewing QTL mapping results in the context of multiple germplasm combinations.

Disequilibrium and association in barley: Thinking outside the glass

“…ABC14350 coincides with the predicted linkage map position of the Fr2 lowtemperature tolerance quantitative trait locus and a CBF gene cluster (9). It is tempting to speculate that the winter vs. spring structural division is caused by allelic variation at one or more CBF genes involved in regulating the lowtemperature tolerance pathway (10).…”

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

“…The barley genome harbors more than 20 CBF coding sequences in a single genotype (Skinner et al 2005). At least 13 of these colocalize in a cluster on the long arm of chromosome 5 (Skinner et al 2005(Skinner et al , 2006Miller et al 2006;Badawi et al 2007;Francia et al 2007;Knox et al 2010). These CBFs are grouped into two phylogenetic subgroups-HvCBF3/ CBFIII and HvCBF4/CBFIV, both of which are unique to the grasses (Skinner et al 2005;Badawi et al 2007).…”

Yield stability for cereals in a changing climate

“…It has been documented that within 15 min of exposure to low temperatures CBF transcripts accumulate within the plant (Gilmour et al 1998). In barley, 20 CBF genes have been identified; half of these are located in two tight clusters on the long arm of chromosome 5H in the same region as the Fr-H2 frost resistance locus (Francia et al 2004;Skinner et al 2006). A similar gene cluster at the orthologous region on chromosome 5A in diploid wheat (Triticum monococcum) is also located at the Fr-A m 2 frost resistance QTL for the level of transcription of the cold-regulated gene COR14b at 15 C. (Snape et al 2001;Vágújfalvi et al 2003;Miller et al 2006).…”