Regulation of hydrogen peroxide accumulation and death of Agrobacterium-transformed cells in tomato transformation

A nonpathogenic rhizobacterium, Pseudomonas putida LSW17S, elicited systemic protection against Fusarium wilt and pith necrosis caused by Fusarium oxysporum f. sp. lycopersici and P. corrugata in tomato (Lycopersicon esculentum L.). LSW17S also confers disease resistance against P. syringae pv. tomato DC3000 (DC3000) on Arabidopsis ecotype Col-0. To investigate mechanisms underlying disease protection, expression patterns of defense-related genes PR1, PR2, PR5, and PDF1.2 and cellular defense responses such as hydrogen peroxide accumulation and callose deposition were investigated. LSW17S treatment exhibited the typical phenomena of priming. Strong and faster transcription of defense-related genes was induced and hydrogen peroxide or callose were accumulated in Arabidopsis treated with LSW17S and infected with DC3000. In contrast, individual actions of LSW17S and DC3000 did not elicit rapid molecular and cellular defense responses. Priming by LSW17S was translocated systemically and retained for more than 10 days. Treatment with LSW17S reduced pathogen proliferation in Arabidopsis ecotype Col-0 expressing bacterial NahG; however, npr1, etr1, and jar1 mutations impaired inhibition of pathogen growth. Cellular and molecular priming responses support these results. In sum, LSW17S primes Arabidopsis for NPR1-, ethylene-, and jasmonic acid-dependent disease resistance, and efficient molecular and cellular defense responses.

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Hydrogen Peroxide Accumulation Regulated by LjRbohD Modulates Nodulation of Lotus japonicus Under Blue Light

10.22541/au.163253691.14999670/v1 ◽

2021 ◽

Author(s):

Jinqiu Liao ◽

Li Liu ◽

Xiaoyan Liu ◽

Yukun Shang ◽

Ming Yuan ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Nitrogen Fixation ◽

Blue Light ◽

Hairy Roots ◽

Direct Relationship ◽

Lotus Japonicus ◽

High Expression ◽

Nitrogen Fixation Activity ◽

Hydrogen Peroxide Accumulation ◽

Exogenous H2o2

Abstract In many legumes, roots that are exposed to blue light do not form nodules, and blue light induces the biosynthesis of hydrogen peroxide (H2O2). The mechanism of blue light restraining nodulation is poorly understood. Whether H2O2 induced by blue light inhibits nodulation needs to be further studied. In this work, blue light could promote the production of H2O2, activate the expression of LjRbohD and LjRbohE, while inhibit the expression of LjRbohB. After applying exogenous H2O2 and diphenyleneiodonium chloride (DPI), the results show H2O2 induced by blue light represses the nodulation of MG20. The accumulated H2O2 may be generated by LjRbohD, which supported by Q-PCR. Cryptochrome 1A, a blue light photoreceptor, is high expression under blue light. However, there seems to be no direct relationship between LjRbohD and LjCry1A. On the contrary, LjRbohB, a positive governor in the regulation of nitrogen fixation activity in L. japonicus, may be negatively regulated by LjCry1A according to the hairy roots transformation results. Therefore, the mechanisms of regulating the nodulation in L. japonicus by LjRbohB and LjRbohD are quite different under blue light. Keywords: Louts japonicus, accumulated H2O2, blue light, nodulation, LjRbohs.

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