Analysis of DNA Methylation of Wheat in Response to Low Nitrogen Stress Based on Mathylation-Sensitive Amplified Polymorphisms

Abiotic stress can induce considerable changes in the composition and quality of wheat grain and cause genomic DNA methylation. Here, methylation-sensitive amplified polymorphism (MSAP) was used to detect the effect of low nitrogen stress on the extent and patterns of DNA methylation in wheat grain at 5, 8, 11, 14, 16 and 21 days post-anthesis (DPA). First, our results showed that low nitrogen stress could reduce grain N content, sodium dodecylsulfate sedimentation (SDS) volume, the amounts of high-molecular-weight glutenin subunits (HMW-GS 2, 12 and 20) and total protein. Then, at 8, 11 and 21 DPA, the overall level of DNA methylation in low nitrogen group was higher than in control group with the maximum difference of 14.1% at 21 DPA. And, at 8 DPA, methylation / demethylation revealed the highest level under low nitrogen conditions, about 17.07% -30.99% of the CCGG sites. Thus, thirteen differentially displayed DNA fragments in MSAP profiles in samples at 8 DPA were further cloned for sequencing analysis. Homology analysis for these DNA fragments showed that most of them were involved in storage matter (protein, fatty acid), some engaged in stress signaling and physiological response regulation. Moreover, the relative expression levels revealed that the expression of a demethylated fragment was increased but the expressions of two other methylated fragments decreased. In conclusion, our results suggested that low nitrogen stress could decrease SDS volume, HMW-GS amount and total protein which might be associated with DNA methylation. (C) 2018 Friends Science Publisher