Browsing by Author "Nakashima, Jin"

Now showing 1 - 3 of 3

An iron-activated citrate transporter, MtMATE67, is required for symbiotic nitrogen fixation
(American Society of Plant Biologists, 2018) Kryvoruchko, Igor S.; Routray, Pratyush; Sinharoy, Senjuti; Torres-Jerez, Ivone; Tejada-Jiménez, Manuel; Finney, Lydia A.; Nakashima, Jin; Pislariu, Catalina I.; Benedito, Vagner A.; González-Guerrero, Manuel; Roberts, Daniel M.; Udvardi, Michael K.
Iron (Fe) is an essential micronutrient for symbiotic nitrogen fixation in legume nodules, where it is required for the activity of bacterial nitrogenase, plant leghemoglobin, respiratory oxidases, and other Fe proteins in both organisms. Fe solubility and transport within and between plant tissues is facilitated by organic chelators, such as nicotianamine and citrate. We have characterized a nodule-specific citrate transporter of the multidrug and toxic compound extrusion family, MtMATE67 of Medicago truncatula. The MtMATE67 gene was induced early during nodule development and expressed primarily in the invasion zone of mature nodules. The MtMATE67 protein was localized to the plasma membrane of nodule cells and also the symbiosome membrane surrounding bacteroids in infected cells. In oocytes, MtMATE67 transported citrate out of cells in an Fe-activated manner. Loss of MtMATE67 gene function resulted in accumulation of Fe in the apoplasm of nodule cells and a substantial decrease in symbiotic nitrogen fixation and plant growth. Taken together, the results point to a primary role of MtMATE67 in citrate efflux from nodule cells in response to an Fe signal. This efflux is necessary to ensure Fe(III) solubility and mobility in the apoplasm and uptake into nodule cells. Likewise, MtMATE67-mediated citrate transport into the symbiosome space would increase the solubility and availability of Fe(III) for rhizobial bacteroids.
The nodule-specific PLAT-domain protein NPD1 is required for nitrogen-fixing symbiosis
(American Society of Plant Biologists, 2019) Pislariu, Catalina I.; Sinharoy, Senjuti; Torres-Jerez, Ivone; Nakashima, Jin; Blancaflor, Elison B.; Udvardi, Michael K
Symbiotic nitrogen fixation by rhizobia in legume root nodules is a key source of nitrogen for sustainable agriculture. Genetic approaches have revealed important roles for only a few of the thousands of plant genes expressed during nodule development and symbiotic nitrogen fixation. Previously, we isolated over one hundred nodulation and nitrogen fixation mutants from a population of Tnt1-insertion mutants of Medigaco truncatula (Pislariu et al., 2011). Using Tnt1 as a tag to identify genetic lesions in these mutants, we discovered that insertions in a nodule-specific PLAT (Polycystin-1, Lipoxygenase, Alpha-Toxin) domain-encoding gene, MtNPD1, resulted in development of ineffective nodules. Early stages of nodule development and colonization by the nitrogen fixing bacterium Sinorhizobium meliloti appeared to be normal in the npd1 mutant. However, npd1 nodules ceased to grow after a few days, resulting in abnormally small, ineffective nodules. Rhizobia that colonized developing npd1 nodules did not differentiate completely into nitrogen-fixing bacteroids and quickly degraded. MtNPD1 expression was low in roots but increased significantly in developing nodules four days post-inoculation (DPI), and expression accompanied invading rhizobia in the nodule infection zone and into the distal nitrogen fixation zone. A functional MtNPD1:GFP fusion protein localized in the space surrounding symbiosomes in infected cells. When ectopically expressed in tobacco (Nicotiana tabacum) leaves, MtNPD1 co-localized with vacuoles and the endoplasmic reticulum. MtNPD1 belongs to a cluster of 5 nodule-specific single PLAT domain-encoding genes, with apparent non-redundant functions.
A novel role of salt and drought induced RING 1 protein in modulating plant defense against hemibiotrophic and necrotrophic pathogens
(American Phytopathological Society, 2021) Ramu, Vemanna S.; Oh, Sunhee; Lee, Hee-Kyung; Nandety, Raja Sekhar; Oh, Youngjae; Lee, Seonghee; Nakashima, Jin; Tang, Yuhong; Senthil-Kumar, Muthappa; Mysore, Kirankumar S.
Many plant encoded E3 ligases are known to be involved in plant defense. Here we report a novel role of E3 ligase SALT- AND DROUGHT-INDUCED RING FINGER1 (SDIR1) in plant immunity. Even though SDIR1 is reasonably well-characterized, its role in biotic stress response is not known. The silencing of SDIR1 in Nicotiana benthamiana reduced the multiplication of the virulent bacterial pathogen Pseudomonas syringae pv. tabaci. The Arabidopsis sdir1 mutant is resistant to virulent pathogens, whereas SDIR1 overexpression lines are susceptible to both host and nonhost hemibiotrophic bacterial pathogens. However, sdir1 mutant and SDIR1 overexpression lines showed hypersusceptibility and resistance, respectively, against the necrotrophic pathogen, Erwinia carotovora. The mutant of SDIR1 target protein, SDIR-interacting protein 1 (SDIR1P1), also showed resistance to host and nonhost pathogens. In SDIR1 overexpression plants, transcripts of NAC transcription factors were less accumulated and the levels of JA and abscisic acid (ABA) were increased. In sdir1 mutants, JA signaling genes JAZ7 and JAZ8 were downregulated. These data suggest that SDIR1 is a susceptibility factor, and its activation/overexpression enhances disease caused by P. syringae pv. tomato DC3000 in Arabidopsis. Our results show a novel role of SDIR1 in modulating plant defense gene expression and plant immunity.