TheLanatatrichome mutation increases stomatal conductance and reduces leaf temperature in tomato

Abstract

Background and aimsTrichomes are epidermal structures with an enormous variety of ecological functions and economic applications. Glandular trichomes produce a rich repertoire of secondary metabolites, whereas non-glandular trichomes create a physical barrier against biotic and abiotic stressors. Intense research is underway to understand trichome development and function and enable breeding of more resilient crops. However, little is known on how enhanced trichome density would impinge on leaf photosynthesis, gas exchange and energy balance.MethodsPrevious work has compared multiple species differing in trichome density, instead here we analyzed monogenic trichome mutants in a single tomato genetic background (cv. Micro-Tom). We determined growth parameters, leaf spectral properties, gas exchange and leaf temperature in the hairs absent (h), Lanata (Ln) and Woolly (Wo) trichome mutants.Key resultsShoot dry mass, leaf area, leaf spectral properties and cuticular conductance were not affected by the mutations. However, the Ln mutant showed increased carbon assimilation (A) possibly associated with higher stomatal conductance (gs), since there were no differences in stomatal density or stomatal index between genotypes. Leaf temperature was furthermore reduced in Ln in the early hours of the afternoon.ConclusionsWe show that a single monogenic mutation can increase glandular trichome density, a desirable trait for crop breeding, whilst concomitantly improving leaf gas exchange and reducing leaf temperature.HIGHLIGHTA monogenic mutation in tomato increases trichome density and optimizes gas exchange and leaf temperature

Leaf trichomes reduce boundary layer conductance

“…We measured d h by microscopy in fresh leaf sections for three leaves per species, as the distance between the exterior edge of the trichome layer and the leaf cuticle at the base of the trichome (Table 2). We measured trichome length in SOLY (genotype Wo ) from images in Gasparini et al (2021); the results were consistent with another study on the same genotype (Zhang et al, 2020).…”

“…Trichome length (trichome layer depth) of the five experimental species. SOLY trichome depth was measured in 3-5 leaves for each species, except for SOLY, which was measured in images provided byGasparini et al (2021) for the same mutant (means ± SE).…”