Model-to-crop translation:interaction between mineral-nutrient availability and steroid hormones
Plants acquire essentialmineral nutrients from inherently heterogeneous soils, in which phosphateavailability vary. Consequently, plants have developed adaptive strategies tocope with low phosphate levels, including alternation between root growth enhancementand attenuation. Using the plant model Arabidopsis, it was recently found thatthe steroid hormone signaling enables root growth plasticity in response tolimited availability of this nutrient. In addition, the molecularmechanism that operates at the base of this interaction was revealed. The aimof this study was to: i) translate these findings to crop using tomato and ii)establish physiological growth conditions outside agar plates that facilitatesthe analysis of the hidden root system in both plants. Indeed, weestablished an inert soil-like substance that allowed us to control the mineralcomposition in the media and thus, to compare root responses of both plantspecies. As part of the translation strategy, we took a pharmacology approachto perturb hormonal levels in tomato and use the CRISPR/CAS9 method to createloss-of-function mutations in select key transcription factors. This revealedthat the root system of tomato is shaped by low phosphate availabilitydepending on the steroid signaling. However, this modulation differed from thatoccurring in Arabidopsis, highlighting the flexibility and adaptive response ofdifferent plants to their environment. In addition, we show that the hormonesignaling affected the homeostasis of select elements, but these were notcommon between tomato and Arabidopsis. Collectively, these data demonstratethat the interaction between phosphate availability and steroid hormones hasdifferent outcome in different plants. Thus, this study highlights the advantageof using various plant systems towards understanding of how plants makedevelopmental decisions in response to heterogeneous soil. Theknowledge in crop could be also harnessed for improving agriculture.