Piriformospora indica volatile organic compounds enhance Arabidopsis root growth by modulating iron deficiency responses via a NO-regulated pathway

• P. indica VOCs enhance Arabidopsis root growth . • Iron acquisition genes are highly upregulated by P. indica VOCs. • NO signaling is crucial for VOC-induced lateral root development in Arabidopsis . • Two fungal VOCs were identified but need further validation. • P. indica VOCs could enhance crop resilience effectively. Volatile organic compounds (VOCs) emitted by microbes can influence plant growth positively or negatively. This study investigated the mechanism by which Piriformospora indica VOCs promote root growth in Arabidopsis . Gene expression changes in Arabidopsis exposed to P. indica VOCs were analyzed using quantitative real-time PCR (qRT-PCR). Additionally, nitric oxide (NO) and iron-deficiency mutants were employed to explore pathways involved in lateral root development, complemented by gas chromatography-quadrupole time-of-flight (GC-QTOF) for VOC detection. P. indica VOCs significantly upregulated iron deficiency response genes, which are crucial for lateral root growth. Furthermore, two novel VOCs released by P. indica were identified within this system. The results thus showed that the observed root growth enhancement occurs through a nitric oxide-regulated pathway, emphasizing the interplay between microbial VOCs and plant physiological responses. In conclusion, P. indica VOCs promote lateral root development by activating iron deficiency responses via an NO-dependent mechanism. These findings provide valuable insights into plant-microbe interactions and suggest opportunities for improving crop growth and agricultural productivity through microbial applications.