The Arabidopsis TTL3 protein interconnects brassinosteroid signalling and cytoskeleton during lateral root development

Lateral roots are essential components of the plant edaphic interface, contributing to water and nutrient uptake, biotic and abiotic interactions, stress survival, and plant anchorage. We have identified the TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE 3 (TTL3) being related to lateral root emergence and later development. TTL3 interacts with microtubules and potentially interconnects cytoskeletal function with the brassinosteroid signalling pathway. Loss of function of TTL3 leads to a reduced number of emerged lateral roots due to delayed development of lateral root primordia. Lateral root growth of the ttl3 mutant is less sensitive to BR treatment. Timing and spatial distribution of TTL3 expression is consistent with its role in development of lateral root primordia before their emergence and subsequent development into lateral roots. TTL3 is a novel component of the root system morphogenesis regulatory network.