SlHSFB3a developmentally regulates lateral root formation by modulating auxin signaling in tomato.

O_LIThe function of HSFs, known otherwise as master thermoregulators, in plant developmental remains largely uninvestigated. C_LIO_LIIn this study, we strategically analyze SlHSFB3a, a class B sub member of HSF transcription factor family, uniquely expresses in age-dependent tomato roots and improves root architecture by synchronizing auxin homeostasis. C_LIO_LIThis data demonstrates SlHSFB3a overexpressed transgenics display higher lateral root (LR) density and early LR emergence improving root architecture. Generation of CRISPR-Knockout mutants displayed contrasting phenotype, confirming SlHSFB3as vital role in root growth. In SlHSFB3a manipulated roots, concentration gradient auxin responses oscillated with increase in LR number. C_LIO_LIWe highlight the signal transduction of SlHSFB3a mediated auxin activation that enhances tomato LRs. SlHSFB3a directly inhibits auxin repressors, increases auxin flow via ARF7/LOB20 pathway and positively modulates LR growth. C_LI