Involved in the regulation of root gravitropism (PubMed:27748769). Functions redundantly with LAZY2 and LAZY4 in the control of root gravitropism (PubMed:27748769). Functions redundantly with LAZY1, LAZY2 and LAZY4 to control plant architecture by coupling gravity sensing to the formation of auxin gradients (PubMed:28821594). Specifically expressed in roots (PubMed:28029738). Expressed in root tips of young seedlings (PubMed:28821594). No visible phenotype under normal growth conditions (PubMed:27748769). Roots of plants lacking LAZY2, LAZY3 and LAZY4 exhibit a negative gravitropic response, and grow upward in the opposite direrction of root gravitropism (PubMed:27748769). Belongs to the LAZY family. Extended C-terminus.