About 8,000 years ago, tetraploid wheat (AABB), which originated in the humid northern humid region of the "Fertile Crescent" of the Middle East, and coarse goat grass (DD), which originated in the arid regions of the south, were naturally hybridized and doubled to form heterologous hexaploid wheat. The addition of the D genome gives wheat greater stress resistance and can be grown in ecological regions of the world. As a donor of wheat D genome, coarse goat grass is an important genetic resource for wheat crop improvement, but its response genes in the process of stress resistance and homologous relationship with wheat have not yet been systematically identified.
Recently, The Crop Journal published a research paper by Liu Jun's team from the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences entitled "Genome-wide characterization of early response genes to abscisic acid coordinating multiple pathways in Aegilops tauschii". At the genome-wide level, the response process of coarse goat grass in response to abscisic acid (ABA) was time-sequenced, and 4818 differentially expressed genes with specific time points in response to ABA stress were identified. Homology identification, expression profiling analysis, and quantitative trait locus (QTL) analysis identified the orthologous gene sucrose of wheat: the sucrose 1-fructotransferase gene (SST), which is involved in the fructooligosaccharide synthesis pathway and is significantly associated with drought tolerance, and is conserved in the evolution of wheat and coarse goat grass. The results provide important information for further analysis of the molecular regulation mechanism of the ABA signal transduction pathway of coarse goat grass, and provide reference for wheat breeding.
Fig. 1 Instantaneous response of coarse goat grass to ABA
Using strand-specific timing transcriptomics studies, the researchers identified 33,548 expressed genes, including 617 that have not yet been annotated. The expression levels of 4818 genes were significantly induced/suppressed by ABA. The expression profile types of these genes can be divided into five categories: transient induction/inhibition of expression, and long-range induction/inhibition of expression. In the transient expression spectrum type, more ABA signal transduction-related genes (PYLs and PP2Cs) and transcription factors (WRKYs, ERFs, NACs, etc.) were identified, while in the long-range expression spectrum, more genes were identified to encode photosynthesis-related proteins.
Figure 2 Genome-wide identification of ABA-responsive genes
Through homologous comparison, a large number of rough goat grass orthogenous homologous genes were identified in the hexaploid wheat genome. The expression profile of hexaploid wheat under ABA treatment was analyzed, and a set of ABA response genes were identified, and there was evolutionary conservatism in the protein sequence and expression profile response characteristics of wheat and coarse goat grass, including important stress-resistant regulatory genes with known functions such as LOX. In addition, combined with the widely used QTL in wheat for analysis, eight wheat homologous genes in response to ABA stress were identified in coarse goat grass. Among them, the wheat SST gene involved in the fructooligosaccharide synthesis pathway is most related to the drought tolerance of wheat, and it is speculated that this gene and its regulated fructooligosaccharide synthesis pathway make wheat gain stress tolerance and adaptability in the heterogeneous multiploidation process.
Author and fund projects
Wei Yu, Cao Liangjing and Huang Xu became co-first authors, and researcher Liu Jun was the corresponding author.
The research was funded by the National Key Research and Development Program and the Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences.
Original link:
https://www.sciencedirect.com/science/article/pii/S221451412030180X
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