Physiological role of reactive oxygen species in chill-sensitive plants

Maize (Zea mays L.), a very important C4 crop, is a chill-sensitive plant. Its chill resistance is related to various elements of the antioxidative system at the cellular level. The specific anatomy and physiology of the C4 photosynthetic type makes its antioxidative strategy more complex compared to C3 plants. The chill resistance of maize depends on several superoxide dismutase (SOD) isozymes which are unequally distributed among the bundle sheath and mesophyll cells, and also on catalase (CAT) and ascorbate peroxidase (APX) activity. CAT is present as three isoforms in both types of photosynthetic cells, whilst APX is restricted to the bundle sheath. CATs show differentiated susceptibility to thermal inhibition. The role of xanthophyll cycle components, alpha-tocopherol and polyamines in literature dealing with the chill resistance of maize is also reviewed. Difficulties can be encountered with the construction of chill-resistant maize transformants because signalling processes in the mesophyll and bundle sheath are not properly recognised.