Carlotta Balconi

Ribosome-Inactivating Proteins in Cereals

Plants constitutively accumulate proteins that are either toxic or inhibitory against pathogens, including ribosome-inactivating proteins (RIPs) and N-glycosidases that depurinate the universally conserved α-sarcin loop of large rRNAs. Cereal RIPs share a high similarity with all the other RIPs; however, they retain characteristic features forming a distinct class which diversified significantly during evolution. They appear involved in several different physiological roles, such as defense against pathogens and/or involved in regulatory and developmental processes. RIPs from cereals generally have low activity against plant ribosomes. In this chapter are reported recent advances in research related to cereal RIPs, with particular emphasis to the maize RIP (b-32) expressed in transgenic plants as an antifungal protein and reliable tool in crop disease management programs.

Breeding for Biotic Stress Resistance/Tolerance in Plants

The long-term goal of crop improvement for biotic stress tolerance in plants is a traditional objective of breeders. Plants must continuously defend themselves against attacks from bacteria, viruses, fungi, invertebrates, and even other plants. This chapter will therefore summarize the benefits and drawbacks of resistance versus chemical protection. Attempts will be made to provide a description on the effective genetic and molecular mechanisms that plants have developed to recognize and respond to infection by a number of pathogens and pests, such as non-host resistance, constitutive barriers and race-specific resistance, including recent advances in elucidating the structure and molecular mechanisms used by plants to cope with pathogens and pest attacks. This chapter also covers the most relevant problems in breeding for resistance to parasites and will include aspects related to specificity of defense mechanisms, specificity of parasitic ability, inheritance of resistance, gene-for-gene interaction, and durability of resistance. Major considerations in breeding for resistance to parasites, conventional sources of resistance and possible alternatives, namely mutation breeding, genetic manipulations, tissue cultures, and molecular interventions to develop plants resistant to pests and pathogens will also be dealt.