Alternative splicing in the coding region of Ppo-A1 directly influences the polyphenol oxidase activity in common wheat (Triticum aestivum L.).
Polyphenol oxidase (PPO) plays a crucial role in browning reactions in fresh and processed fruits and vegetables, as well as products made from cereal grains. Common wheat (Triticum aestivum L.) has a large genome, representing an interesting system to advance our understanding of plant PPO gene expression, regulation and function. In the present study, we characterized the expression of Ppo-A1, a major PPO gene located on wheat chromosome 2A, using DNA sequencing, semi-quantitative RT-PCR, PPO activity assays and whole-grain staining methods during grain development. The results indicated that the expression of the Ppo-A1b allele was regulated by alternative splicing of pre-mRNAs, resulting from a 191-bp insertion in intron 1 and one C/G SNP in exon 2. Eight mRNA isoforms were identified in developing grains based on alignments between cDNA and genomic DNA sequences. Only the constitutively spliced isoform b encodes a putative full-length PPO protein based on its coding sequence whereas the other seven spliced isoforms, a, c, d, e, f, g and h, have premature termination codons resulting in potential nonsense-mediated mRNA decay. The differences in expression of Ppo-A1a and Ppo-A1b were confirmed by PPO activity assays and whole grain staining, providing direct evidence for the influence of alternative splicing in the coding region of Ppo-A1 on polyphenol oxidase activity in common wheat grains.
Institute of Crop Science, National Wheat Improvement Centre/The National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences (CAAS), 12 Zhongguancun South Street, Beijing, 100081, China.
Youwei
Y
Sun
Zhonghu
Z
He
Wujun
W
Ma
Xianchun
X
Xia
D017398:Alternative Splicing; D004156:Catechol Oxidase / Q000235:genetics* / Q000378:metabolism*; D007438:Introns / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014908:Triticum / Q000201:enzymology* / Q000235:genetics*
D012333:RNA, Messenger; D018749:RNA, Plant; D004156:Catechol Oxidase