In recent decades, climate change has led to more frequent and severe drought events, causing serious consequences such as increased forest mortality and significant crop yield losses.... Show moreIn recent decades, climate change has led to more frequent and severe drought events, causing serious consequences such as increased forest mortality and significant crop yield losses. Understanding how drought affects plants, especially economically important herbaceous species, is crucial for predicting and developing drought-resistant crops. To address this issue, this study analyzed a comprehensive dataset of anatomical and hydraulic traits in different genotypes of Arabidopsis thaliana and tomato, including both wild-type and transgenic mutants. The study also investigated the expression of four well-known drought marker genes associated with ABA-dependent and ABA-independent pathways and the impact of overexpressing the JUNGBRUNNEN1 (JUB1) gene on drought response. The findings revealed that each genotype had a unique set of traits to cope with drought, which could be categorized into two response strategies. One group enhanced their drought resistance through traits like a more negative stem P50, thicker intervessel pit membranes, a more lignified inflorescence stem, and a gradual reduction of the low initial stomatal conductance during drought. This strategy enabled them to maintain a relatively high and stable leaf water potential (Ψl). The second group, represented by JUB1 overexpression genotypes, relied primarily on maintaining a high Ψl which is possibly due to osmoprotectant accumulation in leaves, while the other traits have not been recorded. Overall, this research demonstrated the adaptive capabilities of herbaceous plants to drought conditions, highlighting the intraspecific variation in drought responses that underscores the need for a detailed assessment of drought-responsive traits to improve crop yield in a warming world. Show less
More intense droughts under climate change threaten species resilience. Hydraulicstrategies determine drought survival in woody plants but have been hardly studied in herbaceous species. Weexplored... Show moreMore intense droughts under climate change threaten species resilience. Hydraulicstrategies determine drought survival in woody plants but have been hardly studied in herbaceous species. Weexplored the intraspecific variability of hydraulic and morphological traits as indicators of dehydration tolerancein a perennial grass, cocksfoot (Dactylis glomerata), which has a large biogeographical distribution in Europe. Twelve populations of cocksfoot originating from Mediterranean, Temperate and Northern Europeanareas were grown in a controlled environment in pots. Dehydration tolerance, leaf and stem anatomical traits andxylem pressure associated with 88 or 50 % loss of xylem conductance (P88, P50) were measured. Across the 12 populations of cocksfoot, P50 ranged from –3.06 to – 6.36 MPa, while P88ranged from –5.06 to –11.6 MPa. This large intraspecific variability of embolism thresholds corresponded withthe biogeographical distribution and some key traits of the populations. In particular, P88 was correlated withdehydration tolerance (r = –0.79). The dehydration-sensitive Temperate populations exhibited the highest P88(–6.1 MPa). The most dehydration-tolerant Mediterranean populations had the greatest leaf dry matter content andleaf fracture toughness, and the lowest P88 (–10.4 MPa). The Northern populations displayed intermediate traitvalues, potentially attributable to frost resistance. The thickness of metaxylem vessel walls in stems was highlycorrelated with P50 (r = –0.92), but no trade-off with stem lignification was observed. The relevance of the linkagebetween hydraulic and stomatal traits is discussed for drought survival in perennial grasses. Compared with woody species, the large intraspecific variability in dehydration tolerance andembolism resistance within cocksfoot has consequences for its sensitivity to climate change. To better understandadaptive strategies of herbaceous species to increasing drought and frost requires further exploration of the role ofhydraulic and mechanical traits using a larger inter- and intraspecific range of species. Show less
