How to survive freezing: Ice management strategies of a nival plant species

In the nival zone the snow free time period is short (2–3 months). During this time, Ranunculus glacialis grows and reproduces successfully. We investigated how the challenging environmental conditions are survived from plant to cellular level at a natural growing site at Mount “Kleiner Isidor” in the Central Alps of Tyrol.

We found that atmospheric temperatures did not mirror leaf temperatures. Daily leaf temperatures dropped below zero at a rate of 56%, whereas air frosts occurred only at 17%. Leaf freezing occurred even when air temperature was above 0 °C. Ice nucleation was observed at average at −2.6 °C and started usually independently in each leaf. As the shoot is deep-seated in unfrozen soil we suggest it to act as an efficient ice barrier between leaves. Upon tissue ice formation all mesophyll cells were immediately subjected to freezing cytorrhysis; below −3 °C the cell area was reduced at an average of 48%. Huge ice masses formed in intercellular spaces of the spongy parenchyma. After thawing, photosynthesis was unaffected regardless if ice had formed. Cell walls were pectin rich and triglycerides occurred particularly in the spongy parenchyma.

Ranunculus glacialis defies unfazed recurrent freezing events during the active growing and reproduction phase. Many lowland and crop species are sensitive to freezing throughout development. As due to climate change, devastating spring frost events are anticipated to increase, alpine plants with a high frost survival capability may come into focus of research interest, as they can serve as perfect model organisms for freezing tolerance during active growth.


 

Science_flash_Stegner_fig

Figure 1 - Ranunculus glacialis at a natural growing site on 3185 m a.s.l (a). Huge ice masses (some are indicated by red arrows) are accommodated at sublethal freezing temperatures in the intercellular spaces and cells respond to the presence of ice by severe freezing cytorrhysis (b). Bar width: 100 µm.

 

Stegner M, Lackner B, Schäfernolte T, Buchner O, Xiao N, Gierlinger N, Holzinger A, Neuner G (2020) Winter nights during summer time: stress physiological response to ice and the facilitation of freezing cytorrhysis by elastic cell wall components in the leaves of a nival species. International Journal of Molecular Sciences 21:18. https://doi.org/10.3390/ijms21197042


 


Previous Science Flash contributions: 

The multifunctionality of mountain landscapes

Pros and cons of using a standard protocol to test germination of Alpine species

Agent-Based Modelling of a Coupled Water Demand and Supply System

Wolbachia megadiversity: 99% of these microorganismic manipulators unknown

DP ABGC Student Paper Awards 2019

Benthic Diatom Communities in an Alpine River Impacted by Waste Water Treatment Effluents as Revealed Using DNA Metabarcoding

The microbiome of plants: R. glacialis and its rhizobiome along a high-alpine altitudinal gradient

Lots of ‘junk’ in the genome of a small aquatic invertebrate

A dataset for future monitoring of climate change effects in Alpine streams 

Forest fires: How surviving trees can suffer from heat injuries

 


Guidelines for Science Flash contributions

Nach oben scrollen