AUTHOR=Qiu Ailian , Liu Zhiqin , Li Jiazhi , Chen Yanshen , Guan Deyi , He Shuilin 

TITLE=The Ectopic Expression of CaRop1 Modulates the Response of Tobacco Plants to Ralstonia solanacearum and Aphids

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01177

DOI=10.3389/fpls.2016.01177

ISSN=1664-462X

ABSTRACT=<p>In plants, Rho-related GTPases (Rops) are versatile molecular switches that regulate various biological processes, although their exact roles are not fully understood. Herein, we provide evidence that the ectopic expression of a Rop derived from <italic>Capsicum annuum</italic>, designated CaRop1, in tobacco plants modulates the response of these plants to <italic>Ralstonia solanacearum</italic> or aphid attack. The deduced amino acid sequence of CaRop1 harbors a conserved Rho domain and is highly homologous to Rops of other plant species. Transient expression of a CaRop1-GFP fusion protein in <italic>Nicotiana benthamiana</italic> leaf epidermal cells revealed localization of the GFP signal to the plasma membrane, cytoplasm, and nucleus. Overexpression (OE) of the wild-type CaRop1 or its dominant-negative mutant (DN-CaRop1) conferred substantial resistance to <italic>R. solanacearum</italic> infection and aphid attack, and this effect was accompanied by enhanced transcriptional expression of the hypersensitive-reaction marker gene <italic>HSR201</italic>; the jasmonic acid (JA)-responsive <italic>PR1b</italic> and <italic>LOX1</italic>; the insect resistance-associated <italic>NtPI-I</italic>, <italic>NtPI-II</italic>, and <italic>NtTPI</italic>; the ethylene (ET) production-associated <italic>NtACS1</italic>; and <italic>NPK1</italic>, a mitogen-activated protein kinase kinase kinase (MAPKKK) that interferes with N-, Bs2-, and Rx-mediated disease resistance. In contrast, OE of the constitutively active mutant of CaRop1(CA-CaRop1) enhanced susceptibility of the transgenic tobacco plants to <italic>R. solanacearum</italic> infection and aphid attack and downregulated or sustained the expression of <italic>HSR201</italic>, <italic>PR1b</italic>, <italic>NPK1</italic>, <italic>NtACS1</italic>, <italic>NtPI-I</italic>, <italic>NtPI-II</italic>, and <italic>NtTPI</italic>. These results collectively suggest that CaRop1 acts as a signaling switch in the crosstalk between Solanaceaes’s response to <italic>R. solanacearum</italic> infection and aphid attack possibly via JA/ET-mediated signaling machinery.</p>