A Transcriptomic Analysis of Wheat-Barley 7HL-Addition Line: Genomic Interactions Between Host and Alien Genomes in Products of Interspecific Hybridization

For wheat as for many other crops, it is mandatory to increase genetic diversity of current cultivated varieties in order to satisfy the demands of the growing human population and sustain the productivity threatened by climate changes. While alien gene transfer represents an attractive approach for wheat improvement and is practiced for nearly 150 years, this strategy still suffers from major drawbacks reflecting genetic incompatibility between wheat and its relatives. Here we performed an RNA-seq analysis of hexaploid wheat cv. Chinese Spring (2n=6x=42, AABBDD), barley cv. Betzes (2n=2x=14, HH) and a wheat^CS-barley^Bet ditelosomic addition line 7HL, in order to reveal changes resulting from the intergenomic interactions. We compared the expression of wheat and barley genes in their own genomic background against the expression of the same gene set in the 7HL addition line. It allowed us to observe that most (98.7%) of alien genes introgressed into wheat genetic background are repressed, while host genes are mostly (98.5%) unaffected in their expression. Interestingly, a small proportion of barley 7HL genes (1.1%) are not differentially expressed in the wheat background as expressed in the barley parent. Moreover, few wheat genes are up- (0.5%) or down- (0.9%) regulated in the presence of alien chromatin. The analysis of those genes within their genomic, structural and evolutionary context will allow us identifying genes that may relate to the process of making inter-species crosses more compatible so that more wheat-alien introgression lines make their way into practical use.