Abstract Sugarcane is a crop of major importance used mainly for sugar and biofuel production, and many additional applications of its byproducts are being developed. Sugarcane cultivation is plagued by many insect pests and pathogens that reduce sugarcane yields overall. Recently emerging studies have shown complex multitrophic interactions in cultivated areas, such as the induction of sugarcane defense-related proteins by insect herbivory that function against fungal pathogens that commonly appear after mechanical damage. Fungi and viruses infecting sugarcane also modulate insect behavior, for example, by causing changes in volatile compounds responsible for insect attraction or repelling natural vector enemies via a mechanism that increases pathogen dissemination from infected plants to healthy ones. Interestingly, the fungus Fusarium verticillioides is capable of being vertically transmitted to insect offspring, ensuring its persistence in the field. Understanding multitrophic complexes is important to develop better strategies for controlling pathosystems affecting sugarcane and other important crops and highlights the importance of not only studying binary interactions but also adding as many variables as possible to effectively translate laboratory research to real-life conditions.

Abstract Sugarcane is one of the most important agricultural crops in the world. However, pathogen infection and herbivore attack cause constant losses in yield. Plants respond to pathogen infection by inducing the expression of several protein types, such as glucanases, chitinases, thaumatins, peptidase inhibitors, defensins, catalases and glycoproteins. Proteins induced by pathogenesis are directly or indirectly involved in plant defense, leading to pathogen death or inducing other plant defense responses. Several of these proteins are induced in sugarcane by different pathogens or insects and have antifungal or insecticidal activity. In this review, defense-related proteins in sugarcane are described, with their putative mechanisms of action, pathogen targets and biotechnological perspectives.

Nesta revisão, a interação planta-inseto é abordada como um sistema dinâmico, sujeito a contínuas variações e mudanças. As plantas desenvolveram diferentes mecanismos para reduzir o ataque de insetos, incluindo respostas específicas que ativam diferentes vias metabólicas as quais alteram consideravelmente suas características químicas e físicas. Por outro lado, os insetos desenvolveram várias estratégias para superar as barreiras defensivas das plantas, permitindo a sua alimentação, desenvolvimento e reprodução em seus hospedeiros. Esta revisão enfoca vários aspectos desta complexa interação entre plantas e insetos, incluindo substâncias derivadas de compostos químicos, moléculas produzidas a partir do processamento de proteínas e compostos voláteis das plantas, enquanto que a metabolização, seqüestro ou fuga são empregados em contrapartida pelos insetos.

In this review, plant-insect interaction is discussed as a dynamic system, subjected to continual variation and change. Plants developed different mechanisms to reduce insect attack, including specific responses that activate different metabolic pathways which considerably alter their chemical and physical aspects. On the other hand, insects developed several strategies to overcome plant defense barriers, allowing them to feed, grow and reproduce on their host plants. This review foccuses on several aspects of this complex interaction between plants and insects, including chemical-derived substances, protein-derived molecules and volatile compounds of plants whereas metabolization, sequestration or avoidance are in turn employed by the insects.

Deciphering plant-insect interactions at the molecular level is one of the major topics of interest in contemporary plant biology research. In the last few years, various aspects of the plant response to insect damage have been investigated, including the characterization of direct and indirect responses, the regulation of gene expression resulting from insect attack and the signal transduction pathways. Such research has resulted in the proposal of new methods to enhance host resistance to insect pests, including the use of insecticidal genes that can be transferred by genetic engineering into target crops. By integrating the understanding of how plants react to insect damage with the techniques of molecular biology researchers should be able to increase the wide range of methods available for the control of insect pests. The sugarcane transcriptome project (SUCEST) has allowed the identification of several orthologues genes involved in the plant response to insect damage. In this paper we summarize several aspects of the complex interaction between plants and insects and describe the use of in silico analysis to provide information about gene expression in different sugarcane tissues in response to insect attack.

A phylogenetic analysis of plant FtsH-like proteins was performed using protein sequences from the GENEBANK database and five groups of plant FtsH-like proteins were identified by neighbor-joining analysis. Prediction of the subcellular location of the proteins suggested that two (FtsH-m1 & FtsH-m2) were mitochondrial and three (FtsH-p1, FtsH-p2, FtsH-p3) were plastid targeting. The phylogenetic profile of plant FtsH-like proteins was used to search sugarcane expressed sequence tag (EST) clusters in the SUCEST database. Initially, 153 clusters presenting homology with FtsH-like proteins were recovered, of which 23 were confirmed by a BLAST search in the GENEBANK database and by comparison of their hidropathy index with that of previously described FtsH-like proteins. Sugarcane presented EST clusters in all phylogenetic groups. In silico expression analysis showed that the groups are differentially expressed in sugarcane tissues, with FtsH-p2 and FtsH-m1 presenting increased levels of expression.