Water-shortage tolerance and recovery after rehydration in the Chihuahuan Desert plant Yucca filifera (Asparagaceae)1

Abstract

We evaluated several mechanisms that enable saplings of Yucca filifera (Chabaud) to endure water shortage. Saplings were exposed to water shortage and subsequent rewatering inside a greenhouse. The response variables were maximum quantum efficiency (Fv/Fm), effective quantum yield of photosystem II (ΦPSII), nonphotochemical quenching (NPQ), electron transport rate (ETR), leaf relative water content, titratable acid (ΔH+), pigment content (chlorophylls a and b, total carotenoids, chlorophyll a+b/carotenoids ratio, and chlorophyll a/ b ratio), antioxidant activity, and proline accumulation. We hypothesized that Y. filifera saplings tolerate water shortage, and that rewatering favors the sapling development. We found that Fv/Fm and ΦPSII values as well as ΔH+ and chlorophyll a/b ratio were strongly affected by water shortage, and their values reverted after rewatering. We also found higher NPQ, antioxidant activity, and proline content during the water-shortage treatment, which might represent mechanisms for preventing photodamage. The high ability of Y. filifera saplings to withstand stress caused by water shortage indicates that it could be a key species for conservation and restoration of degraded arid ecosystems.