Sex-related differences in stress tolerance in dioecious plants: a critical appraisal in a physiological context

Abstract

Sex-related differences in reproductive effort can lead to differences in vegetative growth and stress tolerance. However, do all dioecious plants show sex-related differences in stress tolerance? To what extent can the environmental context and modularity mask sex-related differences in stress tolerance? Finally, to what extent can physiological measurements help us understand secondary sexual dimorphism? This opinion paper aims to answer these three basic questions with special emphasis on developments in research in this area over the last decade. Compelling evidence indicates that dimorphic species do not always show differences in stress tolerance between sexes; and when sex-related differences do occur, they seem to be highly species-specific, with greater stress tolerance in females than males in some species, and the opposite in others. The causes of such sex-related species-specific differences are still poorly understood, and more physiological studies and diversity of plant species that allow comparative analyses are needed. Furthermore, studies performed thus far demonstrate that the expression of dioecy can lead to sex-related differences in physiological traits-from leaf gas exchange to gene expression-but the biological significance of modularity and sectoriality governing such differences has been poorly investigated. Future studies that consider the importance of modularity and sectoriality are essential for unravelling the mechanisms underlying stress adaptation in male and female plants growing in their natural habitat.

Sexual homomorphism in dioecious trees: extensive tests fail to detect sexual dimorphism in Populus

“…While this result was against expectation, it suggests that apart from floral traits, gender is functionally and inherently neutral in both P. trichocarpa and P. balsamifera . This is all the more remarkable as sexual dimorphism in secondary sexual characteristics has been reported for many dioecious trees and shrubs, including poplars 5 . Finding equivalent patterns of trait variation between genders is unusual, but underscores that genetically-based sex does not necessarily result in inherent sexual dimorphism within a species.…”

“…We tested whether inherent sex-based responses might exist depending on changing temperatures (as suggested by refs 3, 5 and 51), and specifically, whether spring phenology traits were altered by advancing spring temperatures through climate warming (e.g. ref.…”

“…It is widespread in animals, but also includes numerous plants (~5–6% of angiosperm species and 43% of plant families) 1 . Similar to animal taxa, dioecious plant species investigated to date also show sexual dimorphism outside primary sexual characteristics (e.g., morphological, physiological, and/or life-history traits) 2–5 . Sexual dimorphism is presumed to result from sexual selection between genders, specifically through antagonistic selection driven by sexual conflict 4, 6–10 .…”

Erratum: Sex differences and plasticity in dehydration tolerance: insight from a tropical liverwort

“…3A), which suggests contrasting male and female reproductive strategies or functions. This contradicts the typical expectation that females of dioecious plants should be less stress-tolerant due to higher resource investment in reproduction (Juvany and Munné-Bosch, 2015). However, there is mixed evidence on the direction of sex-specific stress tolerance Three samples of a single genotype (1F) were used in each treatment level.…”

“…While most studies indicate that males have higher water stress tolerance than females (Juvany and Munné-Bosch, 2015), multiple examples of higher tolerance in females have been observed as well (Ward et al, 2002;S anchez-Vilas and Retuerto, 2009;Melanie et al, 2013). Further complicating matters, some studies have found that sex-linked differences in stress tolerance depend on life stage and environmental conditions (Rakocevic et al, 2009;Juvany and Munné-Bosch, 2015). Notably, higher DhT has been observed for females versus males in some bryophyte species (Newton, 1972;Stieha et al, 2014).…”