scholarly journals SKRINING KETAHANAN SOMAKLON NILAM TERHADAPP PENYAKIT LAYU BAKTERI (Ralstonia solanacearum)

2016 ◽  
Vol 21 (3) ◽  
pp. 131
Author(s):  
S. Y. HARTATI ◽  
E. HADIPOENTYANTI ◽  
AMALIA AMALIA ◽  
NURSALAM NURSALAM
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Screening Method ◽  
Wilt Disease ◽  
Resistance Screening ◽  
Bacterial Wilt Disease ◽  
House Condition ◽  
Moderately Resistant

<p>ABSTRAK</p><p>Layu   bakteri  yang   disebabkan   oleh <em>  Ralstonia   solanacearum <br /> </em>merupakan salah satu penyakit penting pada tanaman nilam. Perakitan <br /> varietas nilam tahan terhadap penyakit tersebut yang dilakukan melalui <br /> induksi keragaman somaklonal telah menghasilkan beberapa somaklon <br /> yang tahan terhadap <em>R. solanacearum</em> secara <em>in-vitro</em>. Tujuan penelitian <br /> adalah menguji tingkat ketahanan somaklon tersebut terhadap penyakit <br /> layu  pada  kondisi  rumah  kaca (<em>in-vivo</em>).  Penelitian  disusun  dalam <br /> Rancangan  Acak  Lengkap  dengan 27  perlakuan, 3  ulangan,  dan 10 <br /> tanaman/ulangan. Sebagian akar dari somaklon nilam dilukai (dipotong), <br /> selanjutnya diinokulasi (disiram) dengan suspensi<em> R. solanacearum</em> dengan <br /> berbagai konsentrasi 10<sup>5</sup>, 10<sup>7</sup>, dan 10<sup>9 </sup><em>cfu</em>/ml, sebanyak 50 ml/tanaman. <br /> Hasil penelitian menunjukkan, bahwa somaklon yang diinokulasi dengan <br /> konsentrasi 10<sup>5 </sup><em>cfu</em>/ml, 50  ml/tanaman  semuanya  tidak  menunjukkan <br /> gejala layu. Somaklon yang diinokulasi dengan konsentrasi 107 dan 10<sup>9</sup></p><p><em>cfu</em>/ml,  50 ml/tanaman, sebagian layu dan mati.  Dari somaklon yang</p><p>7</p><p>diinokulasi dengan konsentrasi 10     <em>cfu</em>/ml, 50 ml/tanaman, 8 di antaranya</p><p>menunjukkan respon sangat tahan, 4 tahan, dan 5 agak tahan. Ke 17 <br /> somaklon tersebut mempunyai intensitas penyakit &lt;50% dan semua lebih <br /> tahan dari pada varietas Sidikalang (agak toleran). Dari 17 somaklon yang <br /> diinokulasi dengan konsentrasi 10<sup>9 </sup><em>cfu</em>/ml, 50 ml/tanaman, 2 di antaranya <br /> sangat tahan dan 7 somaklon tahan. Teknik skrining ini dapat digunakan <br /> sebagai  metode  standar  untuk pengujian  ketahanan  nilam  terhadap <br /> penyakit layu.</p><p>Kata kunci:  Skrining  ketahanan,  somaklon,  nilam,  penyakit  layu,<em>  R. solanacearum.</em></p><p><em> </em></p><p><em></em>ABSTRACT</p><p>Resistance-Screening of Patchouli Somaclones on Bacterial Wilt Disease (Ralstonia solanacearum) </p><p>Bacterial wilt caused by <em>Ralstonia solanacearum </em>is one of the most <br /> important  diseases  on patchouli.  The  developing patchouli resistance <br /> varieties against  wilt  disease  conducted  through the  induction  of <br /> somaclonal variation produced resistant patchouli somaclones against <em>R. <br /> </em><em>solanacearum </em>(in-vitro). The aim of this  research was to screen the <br /> resistance of those patchouli somaclones against wilt disease under a glass <br /> house condition (in-vivo). The research was conducted in a Randomized <br /> Completely Design  with 27 treatments, 3  replicates,  and 10  plants/ <br /> replicate. Some roots of the patchouli somaclones were wounded (cut), <br /> then inoculated (drenched)   with <em>  R.   solanacearum</em>  suspension   in <br /> concentration of 10<sup>5</sup>, 10<sup>7</sup>, and 10<sup>9 </sup><em>cfu</em>/ml; 50 ml/plant. The result showed, <br /> that all the patchouli somaclones inoculated with <em>R. solanacearum</em> 10<sup>5 <br /> </sup>cfu/ml, 50 ml/plant were not show any wilt sympthom. Whereas, some <br /> somaclones inoculated with the higher concentration 10<sup>7 </sup>and 109 cfu/ml, 50 ml/plant were wilted and died. Among the somaclones inoculated with  the concentration of 10<sup>7</sup>  cfu/ml, 50 ml/plant, 8 of them were highly  resistant, 4 were resistant, and 5 were moderately resistant. The disease  intencity of those 17 somaclones were &lt;50% and they were more resistant than  the  Sidikalang  variety  (moderately  tolerant).  Among  those  17 <br /> somaclones inoculated with the concentration of 10<sup>9 </sup>cfu/ml, 50 ml/plant, 2 <br /> of them were highly resistant and 7 were resistant. This screening method <br /> could be used as a standard protocol for patchouli resistance screening <br /> against wilt disease.</p><p>Kata kunci: Screening resistance, somaclone, patchouli, wilt disease, <em>R. solanacearum.</em></p>

scholarly journals Streptomyces sp.: Characterization, Identification and Its Potential as a Ralstonia solanacearum Biological Control Agent in vitro

2019 ◽  
Vol 2 (3) ◽  
pp. 89-96 ◽  
Author(s):  
Rachmad Saputra ◽  
Triwidodo Arwiyanto ◽  
Arif Wibowo
Keyword(s):  
Biological Control ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Biological Control Agent ◽  
Wilt Disease ◽  
Molecular Characteristics ◽  
Streptomyces Sp ◽  
Bacterial Wilt Disease ◽  
Wide Range

Streptomyces sp. bacteria have the potential to produce antibiotic compounds, which are one of the mechanisms that are widely used in biological control. However, in general, biological control mechanisms also occur through competition, cell wall degradation and induced resistance. This study was aimed to determine the physiological, biochemical and molecular characteristics of two isolates of Streptomyces sp. (S-4 and S16 isolates) isolated from the tomatoes roots, and to find out their ability to control Ralstonia solanacearum, which causes bacterial wilt disease on a wide range of hosts. The results showed both Streptomyces sp. isolates had several different physiological and biochemical characteristics and had a different ability to inhibit R. solanacearum in vitro. Streptomyces sp. S-16 isolate had a high similarity with Streptomyces diastaticus subsp. ardesiacus strain NRRL B-1773T based on the molecular identification results. Further research needs to be done to see the potential inhibition of the two Streptomyces isolates in inhibiting the development of bacterial wilt disease in tomato plants caused by R. solanacearum.

scholarly journals Indigenous Bacillus spp. ability to growth promoting activities and control bacterial wilt disease (Ralstonia solanacearum)

2017 ◽  
Vol 18 (4) ◽  
pp. 1562-1567
Author(s):  
YULMIRA YANTI ◽  
TRIMURTI HABAZAR ◽  
REFLINALDON REFLINALDON ◽  
CHAINUR RAHMAN NASUTION ◽  
SRIMANO FELIA
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Wilt Disease ◽  
Subtilis Strain ◽  
Bacillus Sp ◽  
Bacterial Wilt Disease ◽  
Bacillus Spp ◽  
Growth Promoting ◽  
And Control

Yanti Y, Habazar T, Reflinaldon, Nasution CR, Felia S. 2017. Indigenous Bacillus spp. ability to growth promoting activities and control bacterial wilt disease (Ralstonia solanacearum). Biodiversitas 18: 1562-1567. Among the species of Plant Growth Promoting Rhizobacteria, Bacillus spp. has been found to provide beneficial effects to different plant species. Based on our previous research from in planta screening’s method, we found six indigenous strains of Bacillus spp., which had the ability to control bacterial wilt and increased growth and yields of chili. Those were Bacillus subtilis BSn5,q Bacillus sp. RD-AZPVI-03, Bacillus sp. Y81-1, B.cereus strain C38/15, B.cereus strain APSB-03, and B. subtilis strain CIFT-MFB-4158A. This research aimed to characterize the mechanism of selected Bacillus spp. as biocontrol agents of R. solanacearum and as biofertilizer of chili in vitro. We have observed the biocontrol characters (production of HCN, siderophore, biosurfactant, protease, root colonization, and antibiotic), and biofertilizer’s characters (production of Indole Acetic Acid (IAA), ammonia and phosphate solubilization) of Bacillus spp. All strains had ability to produce variable concentrations of IAA, B.subtilis strain CIFT-MFB-4158A can produce siderophore, all isolates cannot produce HCN and biosurfactant, 4 isolates can produce protease. Based on the ability to colonize roots, B.subtilis strain CIFT-MFB-4158A had the best ability to colonize root surface (4.17 x 105 CFU/g root), while B. subtilis BSn5 had the best ability to colonize internal roots (2.08 x 105 CFU/g), and 2 Bacillus strains can suppress R. solanacearum in vitro.

scholarly journals Potensi Limbah Media Jamur Konsumsi untuk Menekan Penyakit Layu Bakteri (Ralstonia solanacearum) pada Tanaman Kentang

Agrikultura ◽  
2015 ◽  
Vol 26 (2) ◽  
Author(s):  
Noor Istifadah ◽  
P. Rizky D. Sianipar
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Wilt Disease ◽  
Oyster Mushroom ◽  
Lentinus Edodes ◽  
Spent Mushroom Substrate ◽  
Organic Matters ◽  
Bacterial Wilt Disease ◽  
Auricularia Auricula

ABSTRACTThe Potential of Spent Mushroom Substrate to Control Bacterial Wilt Disease (Ralstoniasolanacearum) in PotatoBacterial wilt caused by Ralstonia solanacearum is one of important diseases in potato. One ofecofriendly-control measures is the use of organic matters including spent mushroom substrate.This paper discussed the study that examined the potential of spent substrates of oyster mushroom(Pleurotus sp.), shiitake (Lentinus edodes), Auricularia auricula and composted spent mushroomsubstrate to inhibit the growth of Ralstonia solanacearum in vitro and to suppress the diseaseincidence of bacterial wilt disease in potato. The results showed that spent substrate of shiitakemushroom slightly inhibited the growth of R. solanacearum in vitro with inhibition zone 1.5 mm.The spent mushroom substrate applied in the growth medium and drenching its water extractevery week significantly reduced the disease incidence of bacterial wilt disease, however thesuppression level was only 26.1%. The spent substrates of oyster mushroom (Pleurotus sp)., A.auricula and composted spent mushroom substrate did not suppress the disease incidence.Keywords : Lentinus edodes, Pleurotus, Auricularia auricula, organic matters, spent mushroomwater extractABSTRAKLayu bakteri yang disebabkan Ralstonia solanacearum merupakan salah satu penyakit penting padapertanaman kentang. Salah satu cara pengendalian penyakit yang ramah lingkungan adalahdengan menggunakan bahan organik, termasuk limbah media jamur konsumsi. Artikel inimendiskusikan penelitian yang mengkaji potensi limbah media tanam jamur tiram (Pleurotus sp.),jamur shiitake (Lentinus edodes), jamur kuping (Auricularia auricula) dan kompos limbah mediajamur konsumsi untuk menghambat R. solanacearum in vitro serta menekan penyakit layu bakteripada tanaman kentang. Hasil percobaan menunjukkan air rendaman limbah media jamur shiitakerelatif menekan R. solanacearum secara in vitro dengan zona penghambatan 1,5 mm. Limbahmedia jamur shiitake yang diaplikasikan pada medium tanam dan air rendamannya disiramkan ketanaman kentang setiap minggu sekali dapat menurunkan persentase tanaman layu secara nyatadibandingkan dengan kontrol, namun tingkat penekanannya hanya sebesar 26,1%. Limbah mediajamur tiram (Pleurotus sp.), jamur kuping (A. auricula) serta kompos limbah media jamur tidakmenghambat R. solanacearum secara in vitro dan tidak dapat menekan penyakit layu bakteri padatanaman kentang.Kata kunci : Lentinus edodes , Pleurotus, Auricularia auricula, bahan organik, air rendamanlimbah jamur

scholarly journals Sustainable Management of Soil-Borne Bacterium Ralstonia solanacearum In Vitro and In Vivo through Fungal Metabolites of Different Trichoderma spp.

2021 ◽  
Vol 13 (3) ◽  
pp. 1491
Author(s):  
Yancui Guo ◽  
Zhenyu Fan ◽  
Xiong Yi ◽  
Yuhong Zhang ◽  
Raja Asad Ali Khan ◽  
...  
Keyword(s):  
Bacterial Wilt ◽  
Bacterial Population ◽  
Sem Analysis ◽  
Wilt Disease ◽  
Fungal Metabolites ◽  
Trichoderma Spp ◽  
Tomato Plants ◽  
Bacterial Wilt Disease

The efficacy of traditional control measures for the management of plant pathogens is decreasing, and the resistance of these pathogens to pesticides is increasing, which poses a serious threat to global food security. The exploration of novel and efficient management measures to combat plant disease is an urgent need at this time. In this study, fungal metabolites from three Trichoderma spp. (T. harzianum, T. virens and T. koningii) were prepared on three different growth media (STP, MOF and supermalt (SuM)). The fungal metabolites were tested in vitro and in vivo from March–April 2020 under greenhouse conditions in a pot experiment utilizing completely randomized design to test their management of the bacterial wilt disease caused by R. solanacearum in tomato plants. The effect of the fungal metabolites on bacterial cell morphology was also investigated through scanning electron microscopy (SEM) analysis. In vitro investigation showed that the fungal metabolites of T. harzianum obtained on the STP medium were the most effective in inhibiting in vitro bacterial growth and produced a 17.6 mm growth inhibition zone. SEM analysis confirms the rupture of the cell walls and cell membranes of the bacterium, along with the leakage of its cell contents. Generally, fungal metabolites obtained on an STP medium showed higher activity than those obtained on the other two media, and these metabolites were then evaluated in vivo according to three application times (0 days before transplantation (DBT), 4 DBT and 8 DBT) in a greenhouse trial to examine their ability to manage R. solanacearum in tomato plants. Consistent with in vitro results, the results from the greenhouse studies showed a level of higher anti-bacterial activity of T. harzianum metabolites than they did for the metabolites of other fungi, while among the three application times, the longest time (8 DBT) was more effective in controlling bacterial wilt disease in tomato plants. Metabolites of T. harzianum applied at 8 DBT caused the maximum decrease in soil bacterial population (1.526 log cfu/g), resulting in the lowest level of disease severity (area under disease progressive curve (AUDPC) value: 400), and maximum plant freshness (with a resulting biomass of 36.7 g, a root length of 18.3 cm and a plant height of 33.0 cm). It can be concluded that T. harzianum metabolites obtained on an STP medium, when applied after 8 DBT, can suppress soil bacterial population and enhance plant growth, and thus can be used as a safe, environmentally-conscious and consumer-friendly approach to managing bacterial wilt disease in tomato plants and possibly other crops.

scholarly journals PENGGUNAAN FILTRAT Ralstonia solanacearum DALAM SELEKSI KALUS IN VITRO UNTUK KETAHANAN JAHE TERHADAP PENYAKIT LAYU BAKTERI

2020 ◽  
Vol 16 (2) ◽  
pp. 49
Author(s):  
MEYNARTI SARI DEWI IBRAHIM ◽  
OTIH ROSTIANA ◽  
NURUL KHUMAIDA ◽  
SUPRIADI SUPRIADI
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
In Vitro Selection ◽  
Zingiber Officinale ◽  
Selective Medium ◽  
Wilt Disease ◽  
Meristem Culture ◽  
Embryogenic Calli ◽  
Bacterial Wilt Disease

<p>ABSTRAK</p><p>Penyakit layu bakteri yang disebabkan oleh Ralstonia solanacearummerupakan kendala utama budidaya jahe, yang menyebabkan kehilanganhasil lebih dari 90%. Upaya pengendalian yang dilakukan belum optimal,karena tidak tersedianya varietas jahe tahan patogen tersebut. Kendalautama untuk memperoleh varietas jahe yang tahan adalah terbatasnyasumber gen ketahanan dan adanya hambatan fisiologis pada prosespersilangan jahe karena sifat inkompatibilitas sendiri, serta rendahnyafertilitas polen menyebabkan persilangan jahe secara konvensional sulitdilakukan. Seleksi in vitro menggunakan medium selektif yangmengandung filtrat patogen merupakan salah satu metode inkonvensionaluntuk meningkatkan ketahanan tanaman. Penelitian ini dilakukan diLaboratorium Kultur Jaringan dan Laboratorium Penyakit Balai PenelitianTanaman Obat dan Aromatik (Balittro) dari bulan April 2008 sa,mpaiOktober 2008 dengan tujuan untuk mengetahui tingkat ketahanan jahepada stadia kalus terhadap filtrat R. solanacearum dan memperolehkonsentrasi filtrat yang tepat sehingga diperoleh varian kalus baru tahanterhadap filtrat patogen tersebut. Kalus embriogenik jahe putih besar asaleksplan meristem berumur 8 minggu, diseleksi selama 3 minggu di dalammedium proliferasi (MS + 3% manitol tanpa zat pengatur tumbuh),mengandung filtrat R. solanacearum. Seleksi bertingkat dilakukan denganmengaplikasikan filtrat R. solanacearum pada konsentrasi berbeda, yaitu:0; 0,1; 0,2; 0,3; 0,4; 0,5; 1; 2; 3; 4; dan 5%, pada tahap pertama. Padaseleksi tahap kedua, kalus disubkultur ke dalam media yang sama dengankonsentrasi filtrat dinaikkan 10 kali dari konsentrasi awal. Penelitianmenggunakan rancangan acak lengkap, diulang 10 kali. Hasil penelitianmemperlihatkan penggunaan filtrat R. solanacearum di dalam mediumkultur in vitro jahe pada seleksi tahap pertama dan kedua menyebabkanterjadinya perubahan warna kalus dari putih kekuningan menjadi kuningkecoklatan dan coklat kehitaman. Berat dan diameter kalus, jumlahembrio globular serta embrio torpedo berkurang secara nyata setelahperlakuan filtrat, pada seleksi tahap pertama maupun kedua seiring denganbertambah  tingginya  konsentrasi  filtrat.  Konsentrasi  filtrat  R.solanacearum  yang  mampu  menginduksi  dan  menyeleksi  kalusembriogenik berkisar antara 0,3 - 2% dari volume medium seleksi kaluspada seleksi tahap 1 dan 3 - 20% pada seleksi tahap 2.</p><p>Kata kunci : Zingiber officinale Rosc., kalus, seleksi in vitro,ketahanan, filtrat R. solanacearum</p><p>ABSTRACT</p><p>The use of R. solanacearum filtrate in callus selection ofin vitro for ginger resistance to bacterial wilt disease</p><p>Bacterial wilt disease caused by Ralstonia solanacearum is the mainconstraint in ginger cultivation. It often causes significant yield loss ofmore than 90%. Various controlling techniques are not able to overcomethe disease, due to unavailability of resistant ginger cultivar. Limitation inobtaining resistant ginger variety is caused by several factors includingthe lack of resistant gene, physiological barrier due to the selfincompatibility, and low pollen fertility, these cause difficulty inconventional cross breeding. Therefore, genetic variability enhancementhas to be carried out unconventionally, to obtain ginger variety resistant tothe disease. In vitro selection using a selective medium containing filtrateof the pathogen is one of the potential unconventional method to improveginger plant resistance. The study was conducted at Meristem Culture andPlant Disease Laboratories of IMACRI from April to October 2008 aimingat determining the level of resistant ginger on stage of calli to the filtrateof R. solanacearum and to obtain an appropriate concentration of thefiltrate which induced calli variants resistant to the filtrate. Large whiteginger embryogenic calli meristems of 8 weeks old were selected for 3weeks in proliferation medium (MS + 3% mannitol without growthregulators), containing filtrate of R. solanacearum. For that purpose, twostages of in vitro selection were performed by applying differentconcentrations of R. solanacearum filtrate e.g; 0; 0.1; 0.2; 0.3; 0.4; 0.5; 1;2; 3; 4; and 5% at the first stage selection. Those concentrations were thenmultiplied 10 times at the second stage selection. Experiments werearranged in completely randomized design with 10 replicates. Resultsshowed that the use of R. solanacearum filtrate as selection agent in gingerin vitro culture medium has caused changes in calli color from theyellowish white into the blackish brown. In addition, increase of R.solanacearum filtrate concentration at the 1 st and 2 nd selection stages wasin line with the decreased of the calli weight and diameter, as well asnumber of globular and torpedo embryo. The concentration of R.solanacearum filtrate applied at 0.3 to 2% in the 1 st selection followed by3 to 20% in the 2 nd  selection induced resistant embryogenic calli of ginger.</p><p>Key words : Zingiber officinale Rosc., calli, in vitro selection,resistance, R. solanacearum filtrate</p>

scholarly journals ISOLASI DAN UJI KEMAMPUAN BAKTERIOFAG SEBAGAI AGENS PENGENDALI PENYAKIT LAYU BAKTERI (Ralstonia solanacearum) PADA TANAMAN TOMAT

2020 ◽  
Vol 14 (1) ◽  
pp. 8-20
Author(s):  
Fery Abdul Choliq ◽  
Mintarto Martosudiro ◽  
Istiqomah Istiqomah ◽  
Muhammad Fanhash Nijami
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Plaque Assay ◽  
Wilt Disease ◽  
Control Treatment ◽  
Lower Percentage ◽  
Bacterial Cells ◽  
Horticultural Crops ◽  
Bacterial Wilt Disease ◽  
Bacteriophage Infection

Tomato is the top priority in the development of horticultural crops. The obstacle which mostly encountered is Ralstonia solanacearum pathogen attack. Bacteriophage can cause bacterial lysis after they they develop themselves inside the bacteria. The specific of the bacteriophage can provide result quickly, accurately, and efficiently so that it can be used as an alternative to control bacterial wilt disease R. solanacearum environmentally friendly. This study aims to find out the effectiveness of bacteriophage to control the bacterial wilt disease R. solanacearum. The testing method are plaque assay, bacteriophage infections test in various dilutions, bacteriophage infection test in a liquid medium, and transmission electron microscopy test. In the greenhouse scale testing using a Completely Randomized Design (CRD) with 6 treatments and 4 replications. Quantitative data were analyzed using analysis of variance 5% error level and followed by least significant different  test level of 5%. The results showed that bacteriophages can infect R. solanacearum. Bacteriophage can infect bacteria R. solanacearum indicated by the appearance of plaques in NA media, the declining value of absorbance spectophotometer, and can lyse bacterial cells from dilutions 10-1 to 10-9. The morphology of bacteriophages that infect R. solanacearum have hexagonal head structure and it have which is with a size of 200 nm. In the greenhouse scale showed that the symptoms of R. solanacearum appear at 29 days after inoculation. Application of bacteriophages can control R. solanacearum with lower percentage than the control treatment.

scholarly journals The plant-based chimeric antimicrobial protein SlP14a-PPC20 protects tomato against bacterial wilt disease caused by Ralstonia solanacearum

Plant Science ◽  
2019 ◽  
Vol 280 ◽  
pp. 197-205 ◽  
Author(s):  
Tâmara P. Morais ◽  
Paulo A. Zaini ◽  
Sandeep Chakraborty ◽  
Hossein Gouran ◽  
Camila P. Carvalho ◽  
...  
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Wilt Disease ◽  
Antimicrobial Protein ◽  
Bacterial Wilt Disease

scholarly journals A cbb3-Type Cytochrome C Oxidase Contributes to Ralstonia solanacearum R3bv2 Growth in Microaerobic Environments and to Bacterial Wilt Disease Development in Tomato

2010 ◽  
Vol 23 (8) ◽  
pp. 1042-1052 ◽  
Author(s):  
Jennifer Colburn-Clifford ◽  
Caitilyn Allen
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Wilt Disease ◽  
Wild Type ◽  
Low Oxygen ◽  
Tomato Root ◽  
Bacterial Wilt Disease ◽  
Oxygen Conditions

Ralstonia solanacearum race 3 biovar 2 (R3bv2) is an economically important soilborne plant pathogen that causes bacterial wilt disease by infecting host plant roots and colonizing the xylem vessels. Little is known about R3bv2 behavior in the host rhizosphere and early in bacterial wilt pathogenesis. To explore this part of the disease cycle, we used a novel taxis-based promoter-trapping strategy to identify pathogen genes induced in the plant rhizosphere. This screen identified several rex (root exudate expressed) genes whose promoters were upregulated in the presence of tomato root exudates. One rex gene encodes an assembly protein for a high affinity cbb3-type cytochrome c oxidase (cbb3-cco) that enables respiration in low-oxygen conditions in other bacteria. R3bv2 cbb3-cco gene expression increased under low-oxygen conditions, and a cbb3-cco mutant strain grew more slowly in a microaerobic environment (0.5% O2). Although the cco mutant could still wilt tomato plants, symptom onset was significantly delayed relative to the wild-type parent strain. Further, the cco mutant did not colonize host stems or adhere to roots as effectively as wild type. These results suggest that R3bv2 encounters low-oxygen environments during its interactions with host plants and that the pathogen depends on this oxidase to help it succeed in planta.

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