Boric Acid Mediates Self-Incompatibility Response by Affecting Sugar Metabolism in Radish

摘要

Physiological changes and gene expression related to self-incompatibility (SI) in radish were studied when treated with boric acid (BA). The results showed that at 24 and 48 h after the 0.4% BA treatment, the soluble sugar was 14.93 and 37.04% lower than the control, while the content of soluble protein increased by 7.07 and 6.78% compared with the control, respectively. Nonetheless, BA had a little effect on the free proline content. BA treatment also caused deferential expression of genes in radish pistils. Totally, 2021 differentially expressed genes (DEGs) were identified, of which 1024 were up-regulated and 997 were down-regulated. Gene ontology (GO) analysis revealed that the DEGs were grouped into three categories viz., biological process, cell component and molecular function. The binding and catalytic activity of molecular function and cellular process, metabolic process and single-organism process in biological process played major roles. Furthermore, Kyoto encyclopedia of genes and genomes (KEGG) analysis enriched 20 main pathways. The pathways of pentose and glucuronate interconversions, glucosinolate biosynthesis, starch and sucrose metabolism were the most possible pathways affected by BA. The genes affected by BA in the pathways of starch and sucrose metabolism, and pentose and glucuronate interconversions were 39 and 32, respectively. Two DEGs related to β-1, 3-glucanase were identified, both of which were down-regulated. Moreover, four DEGs related to SI protein S1 were found, all of which were down regulated. The quantitative real-time PCR (qRT-PCR) analysis showed that the transcript levels of four SI related genes and two β-1, 3-glucanase genes were consistent with the trends of transcriptome data. These results suggested that exogenous BA remarkably affected the expression of genes which may be related to callose deposition and SI reaction in radish.