Abstract Detail


Thonglim, Ajaree [1], Delzon, Sylvain [2], Larter, Maximilian [3], Karimi, Omid [4], rahimi, Arezoo [4], Offringa, Remko [4], Keurentjes, Joost J. B.  [5], Balazadeh, Salma [4], Smets, Erik [6], Lens, Frederic [7].

Intervessel pit membrane thickness functionally explains best the differences in embolism formation in stems amongst Arabidopsis thaliana accessions.

The formation and spread of drought-induced embolism formation throughout the 3D vessel network could lead to a detrimental level of hydraulic failure, resulting in branch sacrifice or even plant death. Thus, embolism resistance is an essential trait for plants in order to survive under drought conditions. Stems of derived woody species have been shown to be more resistant to embolism formation compared to the stems of their herbaceous relatives, suggesting a functional link between increased woodiness and increased drought stress resistance in various lineages. In this study, we focus on inflorescence stems of the herbaceousArabidopsis thaliana (L.) Heynh, which can produce a limited amount of wood at the base of the stems. Four accessions, including one woody mutant accession (soc1 ful knockout) and three wildtype accessions (Col-0, Sha, and Cvi), were selected based on differences in growth form and drought response. We applied the cavitron centrifuge method to compare stem vulnerability to embolism resistance amongst the four accessions, and linked the hydraulic measurements to detailed anatomical observations using light microscopy (LM) and transmission electron microscopy (TEM) in order to assess the anatomical traits underlying the observed differences in the pressure inducing 50% of embolism resistance (P50). Our data show that the soc1 ful woody mutant is significantly more resistant to drought-induced embolism than herbaceous wildtype accessions, followed by Sha, Col-0 and Cvi. The anatomical feature that best predicts the difference in embolism resistance is intervessel pit membrane thickness (TPM), explaining 33% of P50variation. The TPM-P50 trade-off can be functionally explained by air-seeding: the process that describes the spread of air bubbles throughout the 3D vessel network via pit membrane pores. Thicker intervessel pit membrane have longer pit membrane pores including more pore constrictions, which impede the passage of gas bubbles from an embolized conduit to a functional adjacent conduit. There is no evidence for the direct link between increased woodiness and increased embolism resistance. However, we found that increased woodiness, together with other lignification characters such as theoretical vessel implosion resistance, proportion of fibre wall area per fibre cell area, and proportion of lignified area per total stem area, are all strongly linked to each other. In our dataset, these lignification characters have co-evolved with TPM, which explains why stem mechanical reinforcement is (indirectly) related to increased embolism resistance.

1 - Naturalis Biodiversity Center, Functional Traits, 9517, 2300 RA , Leiden, The Netherlands
2 - BIOGECO INRA, Universite Bordeaux, 33615 Pessac, Bordeaux, France
3 - Naturalis Biodiversity Center
4 - Plant Developmental Genetics, Institute of Biology Leiden, 2333 BE , Leiden, the Netherlands
5 - Wageningen University, Wageningen, The Netherlands
6 - Naturalis Biodiversity Center, PO Box 9517, Leiden, 2300 RA, Netherlands
7 - Naturalis Biodiversity Center, P.O. Box 9517, Leiden, 2300RA, Netherlands

Arabidopsis thaliana
embolism resistance
intervessel pit membrane thickness
stem anatomy
xylem hydraulics.

Presentation Type: Oral Paper
Session: ECOPH1, Ecophysiology I
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 11:15 AM
Number: ECOPH1002
Abstract ID:233
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation

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