Assessing desiccation tolerance of ferns under various humidity conditions

Presentation Type

Poster

Presentation Type

Submission

Keywords

desiccation tolerance, resurrection fern

Department

Biology

Abstract

Desiccation-tolerant (“resurrection”) plants are unique in their ability to dry out and temporarily stop metabolism and then resume function when rehydrated. The dominant theory on the evolution of desiccation tolerance postulates that desiccation tolerance originated when plants colonized dry land, expanding beyond water-based habitats, but overtime desiccation tolerance became unnecessary and was lost in the vegetative tissues (leaves, stems, and roots). It later reemerged in multiple independent evolutions, creating a phylogenetic pattern of desiccation-tolerant plants. In this experiment, we assessed the desiccation tolerance of Adiantum hispidulum and Pellaea rotundifolia in varied humidity conditions, using the desiccation-sensitive Adiantum raddianum as a control. Based on the literature and phylogenetic relationships, we hypothesized that A. hispidulum and P. rotundifolia, unlike A. raddianum, would recover following desiccation. P. rotundifolia is part of the taxa Cheilanthes, which consists of many resurrection ferns, but P. rotundifolia has never been confirmed as desiccation tolerant. A previous study reported desiccation tolerance in A. hispidulum, and we sought to verify their findings. Leaves from individuals of each species were dehydrated in humidity-controlled containers at either 35%, 50%, or 80% relative humidity. Following complete desiccation (Fv/Fm < 0.1), all leaves were rehydrated. Desiccation and recovery of the leaves were assessed by measuring dark-adapted chlorophyll fluorescence (Fv/Fm) daily during drying and rehydrating. The Fv/Fm of all leaves declined while drying, but A. hispidulum and A. raddianum reached the desiccated state faster than P. rotundifolia, in 2-3 days of drying. P. rotundifolia leaves dried at a more variable rate, depending on factors such as the relative humidity, and could take 2-3 days or more than 20 days to fully desiccate. Following rehydration, none of the species recovered photosynthetic capacity, showing that A. raddianum, A. hispidulum and P. rotundifolia are not desiccation tolerant. Our results highlight the importance of individually assessing the desiccation tolerance of all presumed resurrection fern species under varied humidity conditions.

Faculty Mentor

Helen I. Holmlund

Funding Source or Research Program

Academic Year Undergraduate Research Initiative

Location

Waves Cafeteria

Start Date

24-3-2023 2:00 PM

End Date

24-3-2023 4:00 PM

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Mar 24th, 2:00 PM Mar 24th, 4:00 PM

Assessing desiccation tolerance of ferns under various humidity conditions

Waves Cafeteria

Desiccation-tolerant (“resurrection”) plants are unique in their ability to dry out and temporarily stop metabolism and then resume function when rehydrated. The dominant theory on the evolution of desiccation tolerance postulates that desiccation tolerance originated when plants colonized dry land, expanding beyond water-based habitats, but overtime desiccation tolerance became unnecessary and was lost in the vegetative tissues (leaves, stems, and roots). It later reemerged in multiple independent evolutions, creating a phylogenetic pattern of desiccation-tolerant plants. In this experiment, we assessed the desiccation tolerance of Adiantum hispidulum and Pellaea rotundifolia in varied humidity conditions, using the desiccation-sensitive Adiantum raddianum as a control. Based on the literature and phylogenetic relationships, we hypothesized that A. hispidulum and P. rotundifolia, unlike A. raddianum, would recover following desiccation. P. rotundifolia is part of the taxa Cheilanthes, which consists of many resurrection ferns, but P. rotundifolia has never been confirmed as desiccation tolerant. A previous study reported desiccation tolerance in A. hispidulum, and we sought to verify their findings. Leaves from individuals of each species were dehydrated in humidity-controlled containers at either 35%, 50%, or 80% relative humidity. Following complete desiccation (Fv/Fm < 0.1), all leaves were rehydrated. Desiccation and recovery of the leaves were assessed by measuring dark-adapted chlorophyll fluorescence (Fv/Fm) daily during drying and rehydrating. The Fv/Fm of all leaves declined while drying, but A. hispidulum and A. raddianum reached the desiccated state faster than P. rotundifolia, in 2-3 days of drying. P. rotundifolia leaves dried at a more variable rate, depending on factors such as the relative humidity, and could take 2-3 days or more than 20 days to fully desiccate. Following rehydration, none of the species recovered photosynthetic capacity, showing that A. raddianum, A. hispidulum and P. rotundifolia are not desiccation tolerant. Our results highlight the importance of individually assessing the desiccation tolerance of all presumed resurrection fern species under varied humidity conditions.