Chilling Stress in Maize Seedlings

Abstract

Maize is very sensitive to chilling especially during early autotrophic growth. Seemingly, photosynthesis is strongly affected due to the inhibition of certain enzymes of the C 4 and the Calvin cycle. Cold-induced perturbations of phloem loading may have negative feedback effects on photosynthesis, too. The reduced photosynthetic activity promotes dissipative mechanisms and affects the antioxidative defense in maize leaves. Although seedlings can withstand chilling stress without visual symptoms for few days, the development under such conditions results in irreparable damages with developing chloroplasts and the leaf meristem as the first targets. However, development at suboptimal temperature enables seedlings to better withstand further stress probably due to improved dissipative and antioxidative mechanisms. The causal physiological mechanisms for a better chilling tolerance remain still largely unknown; but recently, first QTLs for chilling tolerance of maize seedlings have been identified. Together with the growing amount of information from gene expression studies this may help to finally unravel the mechanism of chilling tolerance.