Lozano, A. C. | bioRxiv Science

bioRxiv2025

Drought, thermal response and climate-patterning in cuticular conductance of the widespread C4 grass, Themeda triandra

O_LIBackground and Aims: Grasslands underpin global biodiversity, carbon storage, and ecosystem resilience, yet are increasingly threatened by rising temperatures and water scarcity. Understanding how key physiological traits respond to drought and heat is essential for ensuring grassland function under future conditions. Here, we investigated intraspecific variation in leaf cuticular traits--specifically minimum cuticular conductance after stomatal closure (gmin) and its response to temperature--in six Australian accessions of Themeda triandra spanning a wide climatic gradient. We asked whether gmin and its response to drought reflect climate-of-origin and whether the cuticle shows a thermal threshold (Tp) beyond which conductance rises sharply. C_LIO_LIMethods: Plants from six accessions were grown under well-watered (control) glasshouse conditions and then exposed to drought. We measured gmin in both control and drought treatments and assessed the response of gmin to increasing temperature (30-55 {degrees}C) using fresh fully hydrated leaves (control). Climatic data for each site of origin were used to explore trait-environment relationships. C_LIO_LIKey results: Under well-watered conditions, gmin showed no link to climate-of-origin. Under drought, however, gmin displayed clearer climate-linked patterns: accessions from cooler, wetter regions had lower values, contrary to expectations. Drought responses varied strongly among accessions, ranging from marked reductions to significant increases in gmin. With increasing temperature, gmin declined gradually and no accession exhibited a distinct phase transition, indicating a thermally stable cuticle. C_LIO_LIConclusions: Themeda triandra shows considerable intraspecific diversity in gmin and its response to drought. The clearer alignment between climate of origin and gmin measured under drought conditions suggests drought stress is an important filter for gmin expression. These findings provide a physiological basis for identifying genotypes with enhanced resilience for use in grassland conservation and restoration under a warming, drying climate. C_LI

ecology↗

bioRxiv2023

CLE11 and CLE10 Suppress Mycorrhizal Colonisation in Tomato

Symbioses with beneficial microbes are widespread in plants, but these relationships must balance the energy invested by the plants with the nutrients acquired. Symbiosis with arbuscular mycorrhizal (AM) fungi occurs throughout land plants but our understanding of the genes and signals that regulate colonisation levels is limited. Here, we demonstrate that in tomato two CLV3/EMBRYO-SURROUNDING REGION (CLE) peptides, SlCLE10 and SlCLE11, act to suppress AM colonisation of roots. Mutant studies and overexpression via hairy transformation indicate SlCLE11 acts locally in the root to limit AM colonisation. Indeed, SlCLE11 expression is strongly induced in AM colonised roots but SlCLE11 is not required for phosphate suppression of AM colonisation. SlCLE11 may act through as yet uncharacterised signalling pathways, as SlCLE11 does not suppress AM colonisation by acting through two previously characterised receptors with roles in regulating AM colonisation, SlFAB (CLAVATA1 orthologue) or SlCLV2. SlCLE10 appears to play a more minor or redundant role, as cle10 mutants did not influence AM, although the fact that ectopic overexpression of SlCLE10 did suppress colonisation suggests SlCLE10 may play a role in regulating AM colonisation. Our findings show that CLE peptides regulate AM colonisation in the non-legume species tomato.

plant biology↗