Treating seeds in menadione sodium bisulphite (msb) primes salt tolerance in arabidopsis by inducing an earlier plant adaptation

Abstract

For the majority of crops, salinity is one of the most important abiotic stresses, since about 20% of irrigatedagricultural land is adversely affected by it. Menadione sodium bisulphite (MSB), a water-soluble vitaminK3o menadione derivative, has been previously reported as a plant defence activator against severalpathogens in a number of species. We have further explored the MSB effects on salt tolerance. In thisstudy, Arabidopsis thaliana wild ecotype Col-0 plants were exposed to prolonged salt (50 mM) stress. Salttreatment resulted in severe growth inhibition. This detrimental effect was lower in terms of relativegrowth rate (RGR) in plants from seeds soaked in 20 mM of MSB. In these plants, the drop in RGR wasnearly 30% lower than untreated plants after 7 days in salt. Furthermore, we found that the salt stressimposed was not enough to disturb photosystem II or induce the expression of several detoxificationgenes. These functional impairments are characteristic of ionic injuries due to high levels of reactiveoxygen species (ROS). At the end of the second week of the experiment, salt-treated plants recover RGRlevels close to those of the control. Under our experimental conditions plants seem to be challenged by anosmotic stress with a minimum ionic imbalance. Those from MSB-treated seeds were primed to induce anearlier proline accumulation. Although no significant expression of ROS detoxification genes was found,several transcription factors involved in ROS signalling were detected after salt addition. In this context,MSB treatment was able to prime these transcription factors, resulting in an early adaptation of plantsin response to salt stress.