Repeated colonization of alpine habitats by Arabidopsis arenosa viewed through freezing resistance and ice management strategies

Abstract

Success or failure of plants to cope with freezing temperatures can critically influence plant distribution and adaptation to new habitats. Especially in alpine environments, frost is a likely major selective force driving adaptation. In Arabidopsis arenosa (L.) Lawalr ee, alpine populations have evolved independently in different mountain ranges, enabling studying mechanisms of acclimation and adaptation to alpine environments.• We tested for heritable, parallel differentiation in freezing resistance, cold acclimation potential and ice management strategies using eight alpine and eight foothill populations. Plants from three European mountain ranges (Niedere Tauern, F ag araș and Tatra Mountains) were grown from seeds of tetraploid populations in four common gardens, together with diploid populations from the Tatra Mountains. Freezing resistance was assessed using controlled freezing treatments and measuring effective quantum yield of photosystem II, and ice management strategies by infrared video thermography and cryomicroscopy.• The alpine ecotype had a higher cold acclimation potential than the foothill ecotype, whereby this differentiation was more pronounced in tetraploid than diploid populations. However, no ecotypic differentiation was found in one region (F ag araș), where the ancient lineage had a different evolutionary history. Upon freezing, an ice lens within a lacuna between the palisade and spongy parenchyma tissues was formed by separation of leaf tissues, a mechanism not previously reported for herbaceous species.• The dynamic adjustment of freezing resistance to temperature conditions may be particularly important in alpine environments characterized by large temperature fluctuations. Furthermore, the formation of an extracellular ice lens may be a useful strategy to avoid tissue damage during freezing.

Divergence in cold tolerance promotes niche differentiation between diploid and polyploid kiwifruits along an altitudinal gradient in Southwest China

“…3, Table 2), which likely implied population‐specific responses to low temperature at different sampling sites (Supporting information). Reciprocal transplantation experiments, combining with thermal analyses of LT 50 and INT, as applied in the studies of a few polyploid herbaceous species (Decanter et al 2020, Kaplenig et al 2022), are needed to unveil how freezing tolerance changes among cytotypes across a broad range, especially in woody species.…”

“…‘Gongju' (Yue et al 2020), indicating a great ability of polyploids to withstand cold stress. However, other experimental results regarding to the LT 50 demonstrate that polyploids have equal (Kaplenig et al 2022) or even lower (Sugiyama 1998, Lu et al 2020) cold tolerance relative to the diploids. Given the notion that divergence in cold tolerance may lead to niche differentiation between polyploids and diploids along the temperature gradient (Decanter et al 2020), it is of great importance to investigate the physiological mechanisms responsible for adaptive strategies of polyploids under cold stress.…”

Frozen mountain pine needles: The endodermis discriminates between the ice‐containing central tissue and the ice‐free fully functional mesophyll

“…Freeze‐dehydration across tissues is known for R. glacialis leaves: in the ice‐free palisade tissue, water is shifted via the symplast to the spongy cells and from there released into intercellular spaces (Stegner et al, 2020b ). In other herbaceous species, ice forms exclusively in fault zones in the leaf (Kaplenig et al, 2022 ) or leaf petiole (McCully et al, 2004 ) and consequently needs to be shifted across tissues or organs.…”

Parallel Differentiation and Plastic Adjustment of Leaf Anatomy in Alpine Arabidopsis arenosa Ecotypes

“…Anatomical traits were studied in leaves of Arabidopsis arenosa (L.) Lawalrée plants from alpine and foothill populations grown in a previously described reciprocal transplantation experiment [ 38 , 78 ]. Briefly, plants were grown from seeds collected in 2014 from at least 10 mother plants each from 16 populations originating from three mountain ranges.…”

“…Microclimatic data were recorded at 6 min intervals with climate stations (CR1000, Campbell Scientific, Logan, UT, USA) powered by solar panels as previously described [ 78 ]. Photosynthetic photon flux density (PPFD) was measured with quantum sensors (QS; SKP 215, Skye Instruments Ltd., Wales, UK), air temperature and relative humidity with temperature and humidity sensors (HC2S3, Campbell Scientific, Logan, UT, USA) and leaf temperature by copper-constant thermocouples placed on the lower leaf surfaces of at least 10 individuals per common garden with a gas-permeable tape (3M Transpore, North Coast Medical Inc., Morgan Hill, CA, USA).…”