Prospects of a holistic approach to the biochemistry of pest and disease resistance in crop plants

Abstract

In our model for the evolutionary behaviour of resistance, the prerequisite for the evolution of a parasite-host relationship is a haphazard tolerance developed by the parasite to a sufficiently big sector of the non-host resistance of the plant. The main defence of plants is horizontal resistance evolved from remaining nonhost resistance. Genes of vertical resistance and vertical parasitic ability are microevolutionary gene-for-gene adaptations within the tolerated sector. The importance of supplementary vertical resistance increases with discontinuity of the host plant in time and space. A holistic approach to the biochemistry of resistance mimics the approach of the parasite, because a successful parasite must be able to cope with the whole chemophenotype of the plant. Chromatographic separation patterns can bring to view the invisible pattern of the chemical total defence and open possibilities to predict the durability of resistance. The patterns can be used to recognize and optimize comprehensive horizontal resistance, and to control that horizontal resistance is not lost at low parasite densities or when it is masked by vertical resistance. Other applications are recognition of strong vertical genes, control of the health consequenses of resistance breeding, and screening of germ plasm collections.