Strategies of desiccation tolerance vary across life phases in the moss Syntrichia caninervis

Abstract

PREMISE Desiccation tolerance (DT) is a widespread phenomenon among land plants, and variable ecological strategies for DT are likely to exist. Using Syntrichia caninervis, a dryland moss and model system used in DT studies, we hypothesized that DT is lowest in juvenile (protonemal) tissues, highest in asexual reproductive propagules (gemmae), and intermediate in adults (shoots). We tested the long‐standing hypothesis of an inherent constitutive strategy of DT in this species. METHODS Plants were rapidly dried to levels of equilibrating relative humidity (RHeq) ranging from 0 to 93%. Postrehydration recovery was assessed using chlorophyll fluorescence, regeneration rates, and visual tissue damage. For each life phase, we estimated the minimum rate of drying (RoDmin) at RHeq = 42% that did not elicit damage 24 h postrehydration. RESULTS DT strategy varied with life phase, with adult shoots having the lowest RoDmin (10‒25 min), followed by gemmae (3‒10 h) and protonema (14‒20 h). Adult shoots exhibited no detectable damage 24 h postrehydration following a rapid‐dry only at the highest RHeq used (93%), but when dried to lower RHs the response declined to <50% of control fluorescence values. Notably, immediately following rehydration (0 h postrehydration), shoots were damaged below control levels of fluorescence regardless of the RHeq, thus implicating damage. CONCLUSIONS Life phases of the moss S. caninervis had a range of strategies from near constitutive (adult shoots) to demonstrably inducible (protonema). A new response variable for assessing degree of DT is introduced as the minimum rate of drying from which full recovery occurs.

Rainfall and gemmiferous shoots influence asexual reproduction in two tropical mosses

“…Once gemmae are formed, they can be ejected by the mechanical action of rainfall (Egunyomi & Olarinmoye 1983, Pohjamo et al 2006. Interestingly, gemmae resist dry environmental conditions before germinating, which can confer an advantage during months with low precipitation (Coe et al 2021). The number of gemmiferous shoots is a good predictor of gemma output per unit area in both species, as demonstrated by the regression models, and it has been exemplified in the liverwort Lophozia ventricosa (Dicks.)…”

Life Without Water

“…The majority of research in plant physiology focuses on vascular plants, but bryophytes also occur in water‐limited habitats and have been extensively studied for their desiccation tolerance—the ability of a plant to rapidly regain function from a fully dehydrated status. Coe et al (2020) assessed not only desiccation tolerance in the moss Syntrichia caninervis , but also did so across life stages to gain a better understanding of the ontogenetic variation in desiccation tolerance. Marks et al (2021) point to other sources of variation in desiccation tolerance, including not only ontogenetic, but also phylogenetic and intraspecific.…”

Syntrichia caninervis adapt to mercury stress by altering submicrostructure and physiological properties in the Gurbantünggüt Desert

“…Among all types of BSCs, mosses crusts are the most common in the world, Syntrichia caninervis is widely distributed across the drylands of the Northern Hemisphere from the Mojave Desert in the United the States through parts of Europe, to the Gurbantünggüt Desert in China 19 . Till now, there are many studies on tolerance strategy to drought 20 , 21 , and the response of physicochemical properties and spectrally monitoring on environmental change 22 , 23 . However, few studies have looked at the tolerance mechanisms of S. caninervis to Hg toxicity.…”