Leaf wax composition and distribution of Tillandsia landbeckii reflects moisture gradient across the hyperarid Atacama Desert

Sergio Contreras,Mark Reyers,Claudio Latorre,Manlio Landahur,Janet Rethemeyer,Andrea Jaeschke,Karla García

doi:10.1007/s00606-021-01800-0

Abstract

In the hyperarid Atacama Desert, water availability plays a crucial role in allowing plant survival. Along with scant rainfall, marine advective fog frequently occurs along the coastal escarpment fueling isolated mono-specific patches of Tillandsia vegetation. In this study, we investigate the lipid biomarker composition of the bromeliad Tillandsia landbeckii (CAM plant) to assess structural adaptations at the molecular level as a response to extremely arid conditions. We analyzed long-chain n-alkanes and fatty acids in living specimens (n = 59) collected from the main Tillandsia dune ecosystems across a 350 km coastal transect. We found that the leaf wax composition was dominated by n-alkanes with concentrations (total average 160.8 ± 91.4 µg/g) up to three times higher than fatty acids (66.7 ± 40.7 µg/g), likely as an adaptation to the hyperarid environment. Significant differences were found in leaf wax distribution (Average Chain Length [ACL] and Carbon Preference Index [CPI]) in the northern zone relative to the central and southern zones. We found strong negative correlations between fatty acid CPI and n-alkane ACL with precipitation and surface evaporation pointing at fine-scale adaptations to low moisture availability along the coastal transect. Moreover, our data indicate that the predominance of n-alkanes is reflecting the function of the wax in preventing water loss from the leaves. The hyperarid conditions and good preservation potential of both n-alkanes and fatty acids make them ideal tracers to study late Holocene climate change in the Atacama Desert.

Highlights

The Atacama Desert is considered to be one of the oldest and most arid deserts on Earth and is an extreme habitat for life development (McKay et al 2003; Hartley et al 2005)
A higher concentration of n-alkanes in leaf waxes might confer to Tillandsia landbeckii individuals a more hydrophobic wax layer to avoid the loss of water from the leaves
A predominance of leaf wax n-alkanes compared with leaf wax fatty acids had been reported in two species of plants living in the Gobi Desert, located between Mongolia and China (Xu et al 2020)

Summary

Introduction

The Atacama Desert is considered to be one of the oldest and most arid deserts on Earth and is an extreme habitat for life development (McKay et al 2003; Hartley et al 2005). (Bromeliaceae family), one of 15 species of the genus Tillandsia, that survive in such extremely arid conditions by developing specialized adaptations for water collection (Rundel et al 1997; Rundel and Dillon 1998; Pinto et al 2006; Latorre et al 2011) Of these 15, only three species are present in the coastal Atacama Desert of northern Chile: T. landbeckii, T. marconae Till & Vitek and rarely T. virescens and T. capillaris Ruiz & Pavon (Rundel and Dillon 1998; Schulz et al 2011; Merklinger et al 2020). The geographic distribution of T. landbeckii extends from southern Peru to the Coquimbo region in Chile (31.65°S) (Smith and Downs 1977; Till 1992) and is restricted to the occurrence and elevation of fog belts (Oka and Ogawa 1984; Ono 1986)

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Conclusion