Identification of the proteins associated with low potassium tolerance in cultivated and Tibetan wild barley

• Ionomics and TMT-labeling based proteomics were used to study low-K tolerance.
• 288 differentially accumulated proteins in K deficient leaves were identified.
• Tibetan wild barley XZ153 has a higher capability of developing low K tolerance.
• A hypothetical model of a low-K tolerance mechanism was presented.

In previous studies, we found Tibetan wild barley accessions with high tolerance to low K. In this study, ionomics and proteomics analyses were done on two wild genotypes (XZ153, tolerant and XZ141, sensitive), and a cultivar (B1031, tolerance to low K) to understand the mechanism of low-K tolerance. XZ153 was much less affected by low K stress than the other two genotypes in plant biomass and shoot K content. A total of 288 differentially accumulated proteins were identified between low-K and normal K treated plants. Among them, 129 proteins related to low-K tolerance were mainly involved in defense, transcription, signal transduction, energy, and protein synthesis. The analysis of tandem mass tag (TMT) detected 51 proteins which were increased in relative abundance under low K in XZ153, but unaltered or decreased in XZ141. The proteomics results showed that XZ153 is highly capable of rearranging ion homeostasis and developing an antioxidant defense system under low-K stress. Moreover, ethylene response and phenylpropanoid pathways could determine the genotypic difference in low-K tolerance. The current results confirmed the possibility of Tibetan wild barley providing low-K tolerant germplasm and identified some candidate proteins for use in developing the cultivars with low-K tolerance.

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