The Plant Cuticle: An Ancient Guardian Barrier Set Against Long-Standing Rivals.

Gulab Chand Arya,Sutanni Sarkar,Asaph Aharoni,Ekaterina Manasherova,Hagai Cohen

doi:10.3389/fpls.2021.663165

Abstract

The aerial surfaces of plants are covered by a protective barrier formed by the cutin polyester and waxes, collectively referred to as the cuticle. Plant cuticles prevent the loss of water, regulate transpiration, and facilitate the transport of gases and solutes. As the cuticle covers the outermost epidermal cell layer, it also acts as the first line of defense against environmental cues and biotic stresses triggered by a large array of pathogens and pests, such as fungi, bacteria, and insects. Numerous studies highlight the cuticle interface as the site of complex molecular interactions between plants and pathogens. Here, we outline the multidimensional roles of cuticle-derived components, namely, epicuticular waxes and cutin monomers, during plant interactions with pathogenic fungi. We describe how certain wax components affect various pre-penetration and infection processes of fungi with different lifestyles, and then shift our focus to the roles played by the cutin monomers that are released from the cuticle owing to the activity of fungal cutinases during the early stages of infection. We discuss how cutin monomers can activate fungal cutinases and initiate the formation of infection organs, the significant impacts of cuticle defects on the nature of plant–fungal interactions, along with the possible mechanisms raised thus far in the debate on how host plants perceive cutin monomers and/or cuticle defects to elicit defense responses.

Highlights

The aerial surfaces of plants are covered by a lipophilic protective shield called the cuticle
The findings described above emphasize that different epicuticular wax components can affect various processes of pathogenic fungal infection, yet these effects are seemingly far more complex than assumed, as demonstrated by Uppalapati et al (2012)
We delineate the multifaceted roles played by epicuticular waxes and released cutin monomers as chemical signaling molecules in the interactions between host plants and pathogenic fungi

Summary

INTRODUCTION

The aerial surfaces of plants are covered by a lipophilic protective shield called the cuticle. Apart from enabling plants to survive in dry environments, the cuticle represents the first line of defense against biotic stresses triggered by a variety of pathogens and pests, including fungi, bacteria, and insects. The cuticle acts as the interface where the complex molecular interactions occur between plant surfaces and pathogens. Many attributes of the cuticle, for example, its architecture, thickness, and biochemistry were associated with altered resistance or susceptibility to pathogens (Manandhar and Hartman, 1995; Gabler et al, 2003; Gomes et al, 2012; Martin and Rose, 2014)

Plant Cuticle Defense Against Fungi

Plant Cuticle Defense Against Fungi C

Findings

CONCLUDING REMARKS