Although Methyl 3-(4-hydroxyphenyl)propionate (MHPP) has been demonstrated to inhibit nitrification, no further studies have been undertaken to characterize the effect of MHPP as a root exudate on plant growth and root system development.
   Prof. XU Jin and his team of Xishuangbanna Tropical Botanical Garden (XTBG) reported that the MHPP acted as an important regulator of the root system architecture (RSA) by inhibiting primary root (PR) elongation and promoting lateral root (LR) formation in Arabidopsis seedlings by regulating the auxin levels in the root tip and modulating meristematic cell division potential.
  The researchers found that MHPP inhibited PR elongation while increasing LR number, thereby modulating the RSA. MHPP improved nutrient element accumulation in plants and inhibited PR elongation by increasing auxin accumulation via increased expression of auxin biosynthesis-related genes. PAT was responsible for the modulation of PR growth in MHPP-treated seedlings.
   They further found that exogenous MHPP increased the levels of auxin signaling by promoting the expression of the indole-3-acetic acid (IAA) biosynthesis-related genes, increasing auxin perception via the destabilization of Aux/IAA, and significantly repressing the expression of PIN4 in root tips. Moreover, MHPP-induced nitric oxide (NO) production promoted an increase in reactive oxygen species (ROS) accumulation in root tips. Inhibition of NO/ROS accumulation ameliorated the MHPP-induced reduction in primary root growth. They also revealed that MHPP significantly induced the accumulation of glucosinolates in roots.
  Based on the results, the researchers concluded that MHPP inhibited PR elongation by regulating the levels of auxin expression, transport, and signaling in roots and consequently altering root meristematic cell division potential, and the NO/ROS pathway was involved in those processes. In addition, treatment with MHPP increased nutrient element uptake and plant defense-related metabolite accumulation in roots.
  The results showed that MHPP modulated plant growth, development, and stress tolerance by inducing morphological and physiological changes in roots.
  The study entitled “The nitrification inhibitor methyl 3-(4-hydroxyphenyl)propionate modulates root development by interfering with auxin signaling via the NO/ROS pathway in Arabidopsis” has been published online in Plant Physiology.

Contact
XU Jin, Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail:  xujin@xtbg.ac.cn
Tel: +86 871 65140420