Transcription factor involved in the control of strigolactone biosynthesis in roots through the activation of the beta-carotene isomerase D27, which participates in a pathway leading to biosynthesis of strigolactones. Interacts with SMOS1. Expressed at low levels in roots. Plants silencing NSP1 and NSP2 exhibit reduced expression of the strigolactone biosynthetic gene D27, reduced levels of strigolactones and increased shoot tillering (PubMed:22039214). Rice NSP2 is a homolog of Lotus japonicus and Medicago truncatula NSP2 genes, which are transcriptional regulators essential for Nod-factor-induced gene expression (Probable). Although rice roots cannot form root nodule symbiosis, rice NSP2 is able to complement a NSP2-deficient mutant in Lotus japonicus (PubMed:20719766). Rice NSP2 is able to complement a NSP2-deficient mutant in Medicago truncatula (PubMed:22039214). Belongs to the GRAS family.