Changes in lipid composition and ultrastructure associated with functional maturation of the cuticle during adult maize leaf development

Abstract

Running Title: Adult maize leaf cuticle developmentHiglight statement: Chemical, ultrastructural and functional analysis of cuticle development in partially expanded adult maize leaves revealed important roles for wax esters and an osmiophilic, likely cutin-rich, layer in protection from dehydration. AbstractAlthough extensive prior work has characterized cuticle composition, function, ultrastructure and development in many plant species, much remains to be learned about how these features are interrelated. Moreover, very little is known about the adult maize leaf cuticle in spite of its significance for agronomically important traits in this major crop. We analyzed cuticle composition, ultrastructure, and permeability along the developmental gradient of partially expanded adult maize leaves to probe the relationships between these features. The water barrier property is acquired at the cessation of cell expansion. Wax types and chain lengths accumulate asynchronously along the developmental gradient, while overall wax load does not vary. Cutin begins to accumulate prior to establishment of the water barrier and continues thereafter. Ultrastructurally, pavement cell cuticles consist of an epicuticular layer, a thin cuticle proper that acquires an inner, osmiophilic layer during development, and no cuticular layer. Cuticular waxes of the adult maize leaf are dominated by alkanes and wax esters localized mainly in the epicuticular layer. Establishment of the water barrier coincides with a switch from alkanes to esters as the major wax type, and the emergence of an osmiophilic (likely cutin-rich) layer of the cuticle proper.

The Arabidopsis mature endosperm promotes seedling cuticle formation via release of sulfated peptides

“…We identified three main cuticle categories, present in all developmental stages, labeled as ''thin interface,'' ''thick interface,'' and ''diffuse.'' In the ''thin interface'' category, the cuticle proper, composed of a darker osmiophilic inner band and a lighter less osmiophilic outer band, was located between a thin cell wall-cuticle interface and an electron-opaque outer layer (Figure 1B) (Bourgault et al, 2020;Jeffree, 2006). Category ''thick interface'' had a thicker electron-opaque band at the cuticle interface and the dark inner band of the cuticle proper (Figure 1B).…”

Plant monounsaturated fatty acids: Diversity, biosynthesis, functions and uses

“…In leaves of Poplar trichocarpa (poplar), odd-numbered monounsaturated alkenes ranging in chain lengths from C23 to C31 and carrying a double bond between carbons 9 and 10 were detected [13], while longer (C33 to C37) 7-and 9-alkenes were observed in the leaf wax of Arabidopsis [56]. Other examples include 9-alkenes observed in Agropyron intermedium, Hordeum vulgare, and Ophrys sphegodes [57][58], 7-alkenes described in Ophrys exaltata [59] and Zea mays [60], 12-alkenes in Ophrys sphegodes [58], 4-, 6-, and 10-alkenes in Zea mays [61].…”

Prioritizing host phenotype to understand microbiome heritability in plants

“…However, our understanding of the traits that shape microbiome composition creates an expectation of finer‐scale microbiome variation within these broad categories. For example, the permeability and wax composition of the leaf cuticle – which shapes the leaf microbiome (Ritpitakphong et al ., 2016) – varies along maize leaves from base to tip (Bourgault et al ., 2019). Relatively few studies have investigated spatial microbiome dynamics within organs, even fewer while also considering host genotype.…”