Abstract
Toxicity caused by high ammonium severely affects plant growth and crop production, it is urgent to breed high NH(4) (+)-tolerant and high-yield plants. However, the molecular mechanisms on the response and tolerance of plant to high NH(4) (+) remain poorly understood. In this study, four different genotypes of Tartary buckwheat (Fagopyrum tataricum Garetn.) were used to investigate the molecular mechanism on high NH(4) (+) response by integrating physiological, transcriptome, and genome analysis. The root and shoot growth of Tartary buckwheat (TB) seedlings were significantly inhibited by 50 and 100 mmol/L NH(4) (+) treatments. High NH(4) (+) inhibits root growth by affecting activities of antioxidant enzymes, thereby suppressing plant growth. In total 426 high NH(4) (+)-responsive common differentially expressed genes (DEGs) were identified in TB. Most of DEGs involved in antioxidant enzyme system, hormone signaling, and N transport and assimilation were down-regulated by high NH(4) (+). Co-expression analysis suggested the possible hub genes in regulating high NH(4) (+) response, such as FtNRT1.14, FtMYB61/52, FtbZIP6/34, FtNAC72/73, and FtLTP14. 19 small secreted peptides (SSPs) encoding genes were respond to high NH(4) (+), including FtCLE7 and FtCEP3. The up-regulation of FtCLE7 expression and down-regulation of FtCEP3 expression may help plants to optimize root perception and response to high NH(4) (+). Additionally, 443 genotype-specific high NH(4) (+)-responsive DEGs with sequence variation were identified by integrating transcriptome and genome re-sequencing data. The TFs such as MYB, MADS, and LBD genes and the RLKs such as FtBAM1/3 may help TB to adapt to high NH(4) (+). This work provides useful information for investigating the mechanisms on TB respond to high NH(4) (+), and the candidate genes for breeding TB with high NH(4) (+) tolerance were suggested.