Contrasting adaptive responses to cope with drought stress and recovery in Cenchrus ciliaris L. and their implications for tissue lignification

TOMMASINO E.; GRUNBERG K.; CARRIZO I.M.; CARLONI E.; LOPEZ COLOMBA E.; BOLLATI, G.

PHYSIOLOGIA PLANTARUM

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2021 vol. 172 p. 762 - 779

0031-9317

Cenchrus ciliaris L. is a widely used species for cattle feed in arid and semi-arid regionsdue to good forage value and known tolerance to drought conditions. Here, we provideinsights to adaptive responses of two contrasting genotypes of C. ciliaris(drought-tolerant ?RN51? and drought-sensitive ?RN1?) to face drought stress andrecovery conditions and the implications for tissue lignification. Drought stresscaused a reversible decrease in the leaf water relationship and damage to photosystemII, leading to an increased generation of reactive oxygen species and lipid peroxidation.Plants of RN51 exhibited a pronounced increase of antioxidant enzymaticactivities. Unlike the drought-sensitive genotype, RN51 exhibited further developmentof lignified tissues and bulliform cells and had the greatest thickness of theadaxial epidermis. Drought stress led to the rapid activation of the expression of ligninbiosynthesis pathway-related enzymes. The transcript level of the caffeoyl-CoAO-methyltransferase gene decreased in RN1, whereas cinnamoyl-CoA reductasetranscripts were increased in RN51. After rewatering, the tolerant genotype recoveredmore rapidly than RN1. Even though the two genotypes survived when theywere exposed to drought stress, RN1 showed the highest reduction in growth parameters,and this reduction was sustained during rewatering. The results indicated thatthe capacity to regulate lipid peroxidation and mitigate oxidative damage could beone of the mechanisms included in tolerance to drought stress. In addition, thedevelopment of foliar characteristics, like thickness of the adaxial epidermis, welldevelopedbulliform cells, and intensive lignified tissues, are considered anatomicaladaptive strategies for drought tolerance in C. ciliaris.