Micro-Electrode Flux Estimation Confirms That the Solanum pimpinellifolium cu3 Mutant Still Responds to Systemin

Frank C Lanfermeijer,Johannes W Stratmann,Robert Malinowski,J Theo M Elzenga,Marten Staal

doi:10.1104/pp.107.110643

Frank C Lanfermeijer, Johannes W Stratmann + Show 3 more

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https://doi.org/10.1104/pp.107.110643

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Abstract

In this study, we introduce the Micro-Electrode Ion Flux Estimation technique as a sensitive and accurate technique to study systemin-induced changes in ion fluxes from isolated nearly intact plant tissues. Our results demonstrate the effectiveness and value of the Micro-Electrode Ion Flux Estimation technique to monitor and characterize those elicitor-induced ion flux changes from intact tissues. We used the method to monitor the systemin-induced changes in ion fluxes from leaf tissue of various plant species, including wild-type and cu3 mutant tomato (Solanum pimpinellifolium) plants, and confirm previous observations, but now in intact leaf tissue. Upon exposure of leaf tissue of plant species from the subtribe solaneae to systemin, the H(+) influx and K(+) efflux were transiently strongly increased. Plant species of other clades did not show a response upon systemin exposure. Although it has been reported that the gene containing the cu3 null mutation is identical to the SR160/tBRI1 gene, which encodes the systemin/brassinosteroid receptor and is essential in systemin and brassinosteroid perception, we observed no differences in the response of H(+) and K(+) fluxes from both wild-type and mutant leaf tissue to systemin. Also, the effects of various pharmacological effectors on systemin-induced flux changes were similar. Moreover, a SR160/tBRI1 transgene-containing tobacco (Nicotiana tabacum) line was insensitive to systemin, whereas both this line and its wild-type predecessor were responsive to the elicitor flg22. Our results support the conclusion that the Cu3 receptor of tomato is not the systemin receptor, and, hence, another receptor is the principal systemin receptor.

Highlights

In this study, we introduce the Micro-Electrode Ion Flux Estimation technique as a sensitive and accurate technique to study systemin-induced changes in ion fluxes from isolated nearly intact plant tissues
TGRC: LA2172) leaf tissue to systemin did not trigger an effect on the ion fluxes, exposure of the tissue to 100 nM systemin after an 18-h recovery period resulted in an increased H1 influx and K1 efflux
The results presented here demonstrate that tobacco cells are responsive to flg22, neither the wild-type nor the 35ST SpSR160/tBRI1-containing tobacco plants respond to systemin, which indicates that systemin is not perceived or that the signal is not processed in the transgenic line that previously was shown to respond to systemin

Summary

Introduction

We introduce the Micro-Electrode Ion Flux Estimation technique as a sensitive and accurate technique to study systemin-induced changes in ion fluxes from isolated nearly intact plant tissues. Our results demonstrate the effectiveness and value of the Micro-Electrode Ion Flux Estimation technique to monitor and characterize those elicitor-induced ion flux changes from intact tissues. We used the method to monitor the systemin-induced changes in ion fluxes from leaf tissue of various plant species, including wild-type and cu mutant tomato (Solanum pimpinellifolium) plants, and confirm previous observations, but in intact leaf tissue. Several of these mechanisms are inducible upon feeding by the herbivore and at the site of feeding and in plant parts at considerable distance from this site This systemic induction of defense is attributed to the plant hormone jasmonic acid (JA) or its derivative methyl jasmonate (Farmer et al, 2003; Lorenzo and Solano, 2005). Of a few of these induced genes their relation with defense is less obvious (Ryan, 2000)

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