Minimal assay detects population-level senescence in the aquatic plant Lemna minor

Thwaites, Victoria1 ; Chmilar, Suzanne 1 ; Luzardo, Amanda1 ; Laird, Robert 1

Published Oct 18, 2024 on Dryad. https://doi.org/10.5061/dryad.tdz08kq7h

Data files

Oct 18, 2024 version files 10.44 KB

Minimal_Assay_Data_2024_01_18.csv

7.96 KB
README.md

2.48 KB

Abstract

At the population level, senescence occurs when older individuals have an increased risk of death and reduced reproduction compared to younger individuals. We investigated senescence in the aquatic plant Lemna minor (common duckweed), an important species for plant senescence research. Our objectives were to (1) confirm or refute the presence of population-level senescence in this model species; (2) develop a minimal assay of senescence requiring only once-weekly data collection; and (3) test whether there were appreciable differences in senescence in plants grown in glass compared to polystyrene petri dishes, with an aim to reducing single-use plastic waste and long-term research materials costs. We found that weekly survival arced downward with age when viewed on a semi-log plot, and weekly production of descendants decreased with age, with both findings indicating population-level senescence that matched previous work using more frequent data-collection (per Objectives 1 and 2). Additionally, we found no noteworthy differences in senescence between plants grown in glass versus polystyrene petri dishes (per Objective 3). The use of weekly data collection could liberate personnel resources for other research-group functions, and could make the Lemna system suitable for senescence- or demography-education exercises. The use of glass dishes could reduce lab waste and expense.

https://doi.org/10.5061/dryad.tdz08kq7h

Authors: Thwaites VC, Chmilar SL, Luzardo AC, and Laird RA.

Journal: Botany

Contact: vc.thwaites@uleth.ca; s.chmilar@uleth.ca; robert.laird@uleth.ca

Description of the data and file structure

We investigated population-level senescence in the aquatic plant Lemna minor using a minimal assay wherein data were collected once per week. In addition to this, we also investigated whether container material (glass versus plastic) affected plant senescence, lifespan, and reproduction (total number of descendants). Data from the experiment can be found in the data file "Minimal_Assay_Data_2024_01_18.csv".

Files and variables

File: Minimal_Assay_Data_2024_01_18.csv

Description: Data collected from the minimal assay experiment.

Variables

ID: focal plant ID number.
position: randomized location on growth shelves (tray-row-column).
dish_type: material of container holding plant; either 'Plastic' (polystyrene), or 'Glass'. 'Blank' indicates a blank dish, not containing a plant.
exclude: whether plants were excluded from statistical analyses (due to factors such as loss of ink dot marking focal plant). '0' indicates inclusion, and '1' indicates exclusion.
date.birth: date that a focal plant was first observed to have detached from its parent during once-weekly data collection (MMM.DD.YYYY).
date.last.repro: date that the last descendants were observed to have been produced by a focal plant during once-weekly data collection (MMM.DD.YYYY). Also considered date of death of focal plant.
[all remaining columns in MMM.DD.YYYY format]: Number of descendant plants (considered ‘descendants’ after detaching on their own from their parent) present at weekly observation date indicated by column header.

Note: 'NA' values indicate missing data. This could be due to the focal plant not yet being born, plant death, or loss of plant due to the loss of the ink dot marking the focal plant.

Code/software

R software is required to run the script.

The code file "Minimal_Assay_R_code_2024_01_18.r" includes the analysis of the experiment. This includes the packages: reshape, survival, survminer, nlme, MuMIn, plotrix, and TeachingDemos.