α-Amylase gene expression during kernel development in relation to pre-harvest sprouting in wheat and triticale

Triticale, an artificial hybrid of wheat and rye, combines the good yield and nutritional value of wheat with good disease resistance of rye. Despite these advantages, pre-harvest sprouting (PHS) can seriously limit triticale production. Although different field and laboratory tests exist, it remains difficult to breed for PHS tolerance and mechanisms behind PHS are still elusive. As part of an integrated study focussing on the genetic and physiological background of PHS, a multidisciplinary approach was pursued monitoring alpha-amylase, an enzyme that is involved in PHS, both at transcriptional and post-transcriptional levels during kernel development. Plants of PHS-tolerant and PHS-susceptible varieties of wheat and triticale were grown under controlled conditions from flowering to harvest. At regular time points, kernels were harvested for germination tests, alpha-amylase analysis and RNA extraction. RNA extracts were used in an RT-qPCR assay to obtain expression profiles of the alpha-Amy1 and alpha-Amy2 genes. The alpha-amylase activity profiles during kernel development corresponded well with results from previous reports. The relative gene expression profiles revealed that alpha-Amy2 peaked in the beginning of kernel development, while alpha-Amy1 increased towards harvest maturity. Furthermore, the relative alpha-Amy1 expression was higher in the PHS-susceptible varieties compared to the PHS-tolerant varieties.