Abstract only

Polyphenol oxidase (PPO) plays a crucial role in browning reactions of wheat-based products. 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 common wheat, PPO activity was mainly determined by Ppo-A1 located on chromosome 2AL. The Ppo-A1a and Ppo-A1b alleles differ mainly in a 191-bp InDel in intron 1 and seven SNPs. In the present study, we characterized the expression levels of Ppo-A1 among eight cultivars during kernel development. The results indicated that cultivars with Ppo-A1a had much higher PPO activity and mRNA abundance than the cultivars with Ppo-A1b during kernel development. The expression of Ppo-A1b allele was regulated by alternative splicing of pre-mRNAs, with eight kinds of mRNA isoforms in the developing kernels. Only the constitutively spliced isoform may encode a putative full-length PPO protein based on its coding sequence, whereas the other alternative spliced isoforms have premature termination codons, resulting in potential nonsense mediated mRNA decay. The differences in the expression of Ppo-A1a and Ppo-A1b were confirmed by whole kernel staining, providing a direct evidence of the influence of alternative splicing in the coding region of Ppo-A1 on polyphenol oxidase activity in common wheat kernels.

Global Wheat Program

English

Lucia Segura

INT2411

CIMMYT Staff Publications Collection