Auxin Modulates Root-Hair Growth Through Its Signaling Pathway in Citrus

The study investigated the effects of auxins on root-hair growth in trifoliate orange, a citrus rootstock, using 3-indolebutyric acid (IBA) and 2-naphthoxyacetic acid (2-NOA, an auxin inhibitor). It was found that IBA positively regulated root-hair growth by increasing the endogenous auxin level in the root-hair zone, while 2-NOA had the opposite effect, reducing root-hair growth. IBA treatment increased the endogenous IAA content by 22.8%, whereas 2-NOA reduced it by 21.4% compared to the control. The study concluded that auxin biosynthesis and transport, modulated by IBA and 2-NOA, played a crucial role in root-hair growth by altering the local auxin signaling pathway.