493 / 2019-02-28 14:52:14

Laterals take it better – improved resistance is observed in emerging and young lateral roots during lethal salt treatments

salt stress, ROS, CYCLINB1, PCD

全体主题 > Abiotic Stress

Plant responses to salinity have been extensively studied over the last decades. Surprisingly, despite the vast accumulated knowledge, the ways Arabidopsis lateral roots (LR) cope with lethal salinity has not been fully resolved: the exact type of cell death that occurs in LR during lethal salinity is still unknown. Moreover, to our knowledge, cell viability and the distribution of ROS were not determined in LR during lethal salinity. Here we show that different root parts responded deferentially to lethal salinity (NaCl 200mM). While the primary root tip (PR) died, emerging and young LR remained strikingly viable. Furthermore, strong CYCLINB1 GUS activity was observed in the LR but not in the PR, indicating cell cycle activity in that position. In addition, uneven distribution of NADPH oxidase activated ROS were detected in the LR and PR during the salt treatment. Furthermore, diphenyleneiodonium (DPI) treatment, which reduced the salinity induced ROS and led to complete LR lethality, suggesting a key role of that ROS in the LR salt tolerance. TUNEL assay and Monodansylcadaverine (MDC) staining revealed that Autophagosome mediated PCD and not Apoptosis like-PCD, was initiated much earlier in the PR position. These results suggest a novel position-dependent resistance pathway which overcomes lethal salinity. This pathway can potentially provide genetic tools for improving salt tolerance in crops and fight the soil salinization process, which threats global food production.