Written by: Hongfei Li
The root system is the first contact of plants with salinity of the soil and we hope you have understood its critical role helping plants to survive salt from our website. Halophytes are plants that thrive under high salt concentrations. Schrenkiella parvula (S. parvula), a halophyte species, belongs to the same Brassicaceae family as the model species Arabidopsis while the salt tolerance of S. parvula is much higher than Arabidopsis. Therefore Hongfei started her PhD focusing on the root system of S. parvula, comparing it with Arabidopsis to investigate effective root strategies in response to salt stress. Some of her exciting results recently have been published in the journal New Phytologist.
We observed root growth of S. parvula was less inhibited under salt stress compared with Arabidopsis. Intriguingly, unlike Arabidopsis, roots of S. parvula do not grow away from salt. Salt-induced abscisic acid levels were higher in S. parvula roots compared with Arabidopsis. Following the leads from the comparative transcriptomic analysis of S. parvula roots with public datasets of Arabidopsis roots, we found that carbon allocation, cell growth and suberization in roots of S. parvula under salt stress may contribute to the salt tolerance of S. parvula. We monitored carbon allocation of S. parvula under salt stress by using 14C labelling. It shows S. parvula is a more stable system under salt stress as the carbon partitioning and metabolism are less perturbated compared to Arabidopsis, which may energize the root growth of S. parvula under salt stress. Root growth is the result of both cell division and elongation. Roots of S. parvula maintain cell elongation but not division under severe salt stress, leading to less growth inhibition by salt compared with Arabidopsis. The suberization in the root layer endodermis can be induced by salt stress. It serves as a barrier limiting Na+ influx in roots which alleviates Na+ toxicity to plants. Roots of S. parvula are capable to increase suberization under high salt stress concentrations that are lethal to Arabidopsis.
In summary, roots of S. parvula are equipped with multiple physiological and developmental adjustments under salt stress to maintain growth, providing new avenues to improve salt tolerance of plants using root-specific strategies.
Summary of root-specific responses of S. parvula compared with Arabidopsis under salt stress. Roots of S. parvula do not avoid high salt concentrations (halotropism) and experience less inhibition of main root growth compared with Arabidopsis, which is likely due to the maintenance of carbon partitioning, cell elongation and suberization in roots.
Roots in Salt 