Cytocises and Receptors on Parasites and Microbes

**Chapter 1**

**Abstract**

pathogens, *Sporisorium*

**1. Introduction**

**3**

Role of the Cytoskeletal

Fungal Spores

*and María Estrella Legaz*

Actomyosin Complex in the

Motility of Cyanobacteria and

*Elena Sánchez-Elordi, Eva María Díaz, Carlos Vicente*

being this a remarkable advance compared to previous results.

**Keywords:** actin, chemotaxis, cytoskeleton, lichens, motility, myosin, *Nostoc*,

The main interactions between plants include epiphytism, mutualism, commensalism, and parasitism, although the frontier between these types of association can be confusing [1]. For example, most epiphytes do not negatively influence their phytophores since they absorb water and nutrients directly from the atmosphere [2]. It is the case of many bromeliads or the crassulaceae *Aeonium arboreum*, growing on the *Phoenix dactylifera* stipe without damaging it (**Figure 1A**), although in some cases, drift toward parasitism is evident, as has been demonstrated by Montaña et al. [3] for epiphytic Bromeliads growing upon *Cercidium praecox*. Many

This study demonstrates the involvement of the cytoskeleton in the movement of cyanobacteria and fungal spores to their hosts to establish a state of symbiosis or pathogenicity. The term symbiosis sensu lato is referred not only to commensalism and mutualism but also to the parasitic aberrations. The establishment of association implies that the endohabitant can move on a wet surface until finding an entry point in the exohabitant surface. In aqueous media, the exohabitant secretes glycoproteins that form a chemoattraction gradient for the invading cells. In lichens, the gradient consists of fungal lectins whose function is to recognize a compatible green alga or cyanobacterium. In the case of pathogens, the secreted proteins usually are a mixture that includes false quorum and chemoattractant signals, and cell wall digestive enzymes. The results indicate that fungal lectins and defense proteins bind to specific cell wall receptors for signaling the activation of cytoskeleton, causing successive cycles of cell contraction-relaxation that permits the migration of the endohabitant. In this study, different biochemical and microscopy techniques have been used. The mechanisms through which the cytoskeleton carries out these cycles of cell contractionrelaxation are described,
