Abstract
The microtubule cytoskeleton is a dynamic system that plays vital roles in fundamental cellular processes and in responses to environmental stumili. Salt stress induced depolymerization and reorganization of microtubules are believed to function in the promotion of survival in Arabidopsis. Microtubule-severing enzyme ATKATANIN1 (AtKTN1) is recognized as a MAP that help to maintain organized microtubule structure. To date, whether AtKTN1 is involved in response to salt stress in Arabidopsis remains unknown. Here, our phenotypic analysis showed that the overexpression of AtKTN1 decreased tolerance to salt stress, whereas the knock-out of AtKTN1 increased salt tolerance in the early stage but decreased salt tolerance in the later stage. Microscopic analysis revealed that microtubule organization and dynamics are distorted in both overexpression and mutant cells which, in turn, resulted in an abnormal disassembly and reorganization under salt stress. Moreover, qRT analysis revealed that stress-responsive genes were down-regulated in overexpression and mutant cells compared to WT cells under salt stress. Taken together, our results indicated roles of AtKTN1 in modulating microtubule organization, salt-stress induced microtubule disruption and recovery, and its involvement in stress-related signaling pathways.
Highlights
Salinity, one of the major environmental factors leading to poor crop growth and yields, impacts over 6% of the world’s land area [1]
To elucidate the underlying mechanism of AtKTN1 in regulating responses to salt stress, further analysis of their organization and dynamics were performed, and the results suggested that AtKTN1 played important roles in modulating salt stress-induced microtubule disassembly and reorganization by manipulating microtubule severing
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Summary
One of the major environmental factors leading to poor crop growth and yields, impacts over 6% of the world’s land area [1]. Arabidopsis Histone H2B monoubiquitination (H2Bub1) modulates salt stress-induced microtubule disassembly, and regulates the PTP-MPK3/6 signaling pathway which participates in the modulation of microtubule stabilization [17]. Recent study showed that ethylene signaling regulated the expression of microtubule-stabilizing protein WAVEDAMPENED2-LIKE5 (WDL5), contributed to the modulation of microtubule organization and dynamics in Arabidopsis under salt stress [19]. Given the presence of microtubule disassembly and reorganization in salt resistance, and importance of AtKTN1 in controlling microtubule organization and dynamics, we hypothesized that AtKTN1 might be involved in responses to salt stress. To elucidate the underlying mechanism of AtKTN1 in regulating responses to salt stress, further analysis of their organization and dynamics were performed, and the results suggested that AtKTN1 played important roles in modulating salt stress-induced microtubule disassembly and reorganization by manipulating microtubule severing. The downregulation of stress induced genes in ktn and 35S::KTN1 seedlings suggested that AtKTN1 was involved in stress related signaling pathways
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