Multi-omics analyses reveal MdMYB10 hypermethylation being responsible for a bud sport of apple fruit color.

Apple bud sports offer a rich resource for clonal selection of numerous elite cultivars. The accumulation of somatic mutations as plants develop may potentially impact the emergence of bud sports. Previous studies focused on somatic mutation in the essential genes associated with bud sports. However, the rate and function of genome-wide somatic mutations that accumulate when a bud sport arises remain unclear. In this study, we identified a branch from a 10-year-old tree of the apple cultivar 'Oregon Spur II' as a bud sport. The mutant branch showed reduced red coloration on fruit skin. Using this plant material, we assembled a high-quality haplotype reference genome consisting of 649.61 Mb sequences with a contig N50 value of 2.04 Mb. We then estimated the somatic mutation rate of the apple tree to be 4.56 × 10 -8 per base per year, and further identified 253 somatic single-nucleotide polymorphisms (SNPs), including five non-synonymous SNPs, between the original type and mutant samples. Transcriptome analyses showed that 69 differentially expressed genes between the original type and mutant fruit skin were highly correlated with anthocyanin content. DNA methylation in the promoter of five anthocyanin-associated genes was increased in the mutant compared with the original type as determined using DNA methylation profiling. Among the genetic and epigenetic factors that directly and indirectly influence anthocyanin content in the mutant apple fruit skin, the hypermethylated promoter of MdMYB10 is important. This study indicated that numerous somatic mutations accumulated at the emergence of a bud sport from a genome-wide perspective, some of which contribute to the low coloration of the bud sport.

[Identification of Daturae flos and its adulterants based on DNA barcoding technique].

To identify the original plant of Daturae Flos from its adulterants by DNA barcoding, the sequences of ITS2, psbA-trnH, matK, rbcL of four species including Datura metel, Darura innoxia, Darura stramonium and Brugmansia arborea were compared and analyzed. The PCR and sequencing success rate of the four regions (ITS2, psbA-trnH, matK, rbcL) was 100%, 90%, 100% and 85%, respectively. Sequences were assembled with CodonCode Aligner. K2P distances were calculated and NJ tree was performed by MEGA 4.1. Thirty SNPs were found among ITS2 sequences, and 33 insert/deletes were found among psbA-trnH intergenic regions. The interspecific K2P distance of ITS2 and psbA-trnH was obviously higher than that of the intraspecific one. As to matK and rbcL, there was no "Barcoding Gap" existing between inter- and intra-specific distances. The NJ trees of the four regions/combinations were built separately. Samples of Brugmansia arborea were clustered into one clade, and the other species of Datura L. formed another clade. The results showed that either ITS2 or psbA-trnH was useful to identify Daturae Flos from its adulterants.