Screening and identification of endophytic bacteria to control bacterial leaf blight disease on Shallot. The experiment was conducted in Laboratory and Green House, from January to June 2012.   Laboratory experiment consisted of three steps:  (1) isolation of endophytic bacteria from healthy onion roots, (2)In planta /screening of endophytic isolates capable of reducing bacterial leaf blight disease, and (3) molecular identification of potential endophytic isolates.  Treatments of  in planta test were arranged in Completely Randomized Design.  Collected isolates were tested for their capability in controlling bacterial leaf blight disease on shallot.  The variables observed were disease incidence, disease severity, and shallot yield. The results showed that out of 82 isolates successfully isolated, 56 isolates (68.29%) were Gram positive, and 26 isolate (31.71%) were Gram negative. All isolates were HR negative and pathogenicity negative. Six endophytic isolates showed  better performance in inducing resistance and increasing onion yield. Based on 16S rRNA sequence the six isolates were  Bacillus cereus strain P14 , Bacillus cereus strain Se07, Bacillus sp H1, Bacillus sp SJ1 and Serratia marcescens strain PPM4.

Solid formulations of indigenous rhizobacteria Bacillus thuringiensis TS2 and storage time to control bacterial pustule disease Xanthomonas axonopodis pv. glycines. Bacterial pustule disease caused by Xanthomonas axonopodis pv. Glycines is a major constraint in soybean cultivation. Indigenous rhizobacteria Bacillus thuringiensis TS2 from soybean rhizosphere acquired from previous research is the best isolate which can control soybean bacterial pustule disease and increase growth rate of soybean. To increased its stability and interaction with soybean plants, Bacillus thuringiensis TS2 was urged to test furthermore especially its formulation with based formula tapioca powder, peat and bulk. The most effective storage time also need to test. Result showed that all rhizobacterial formula had ability to decrease incidence of bacterial pustule disease compared to control. Moreover, all the three formula could increase plant growth, total of leaves, total of branch and yields. Flowering time was also advanced by 1-8 days compared to control. Decreasing of disease rate and increasing of plant growth rate variated between different formulations.

Peroxidase enzyme activity of the introduced shallots with endophytic bacteria and resistant to bacterial leaf blight (Xanthomonas axonopodis pv. allii). Bacterial leaf blight caused by Xanthomonas axonopodis pv. allii is an important disease in shallots. We have earned six isolates of endophytic bacteria, which have the ability to induce systemically resistance to shallots. One mechanism in induce resistance in plants is a change in the plant defense enzyme activity such as peroxidase. The purpose of this study was to calculate the peroxidase enzyme activity of shallots crop is being introduced with endophytic bacteria and is able to induce resistance to Xanthomonas axonopodis pv. allii. This research was conducted by introducing six isolates of endophytic bacteria on shallot bulbs and planted in greenhouse. Shallots crop that was 14 days old then inoculated with the bacterium Xanthomonas axonopodis pv. allii and incubated until symptoms appear. Peroxidase enzyme activity was calculated on the roots and leaves of shallots are 0, 1, 2, 4, 6, 8, 10, 15, and 30 days after inoculation (dai). The results showed an increase in the peroxidase enzyme activity of shallots crop is being introduced by endophytic bacteria compared to the control. Isolates ULG1E2 (Serratia marcescens PPM4) was isolate with the highest peroxidase enzyme activity both in the roots and leaves are 0,051 ìm/ ml.Key words: endophytic bacteria, Shallot, peroxidase enzyme, Xanthomonas axonopodis pv. allii ABSTRAK Aktivitas enzim peroksidase bawang merah yang diintroduksi dengan bakteri endofit dan tahan terhadap penyakit hawar daun bakteri (Xanthomonas axonopodis pv. allii). Penyakit hawar daun bakteri yang disebabkan oleh Xanthomonas axonopodis pv. allii merupakan penyakit yang penting pada pertanaman bawang merah. Penulis telah mendapatkan enam isolat bakteri endofit, yang memiliki kemampuan mengimbas ketahanan tanaman bawang merah secara sistemik. Salah satu mekanisme dalam pengimbasan ketahanan pada tanaman adalah perubahan aktivitas enzim pertahanan tanaman seperti peroksidase. Tujuan penelitian ini adalah menghitung aktivitas enzim peroksidase dari tanaman bawang merah yang diintroduksi dengan isolat bakteri endofit dan mampu mengimbas ketahanannya terhadap Xanthomonas axonopodis pv. allii. Penelitian ini dilakukan dengan mengintroduksikan enam isolat bakteri endofit pada umbi bawang merah dan ditanam di rumah kaca. Tanaman bawang merah yang berumur 14 hari kemudian diinokulasi dengan bakteri Xanthomonas axonopodis pv. allii dan diinkubasi sampai muncul gejala. Aktivitas enzim peroksidase dihitung pada akar dan daun tanaman bawang merah yang berumur 0, 1, 2, 4, 6, 8, 10, 15, dan 30 hari setelah inokulasi (hsi). Hasil penelitian menunjukkan terjadinya peningkatan aktivitasenzim peroksidase pada tanaman bawang merah yang diintroduksi bakteri endofit dibandingkan dengan kontrol. Isolat ULG 1 E 2 (Serratia marcescens PPM4) merupakan isolat dengan aktivitas enzim peroksidase tertinggi baik pada akar maupun daun yaitu 0,051µm/ml. Kata kunci...

Characterization of Endophytic Bacillus Isolated from Shallot Root as Biocontrol of Bacterial Leaf Blight Disease. Endophytic Bacillus isolated from the roots of healthy shallots has potential as biological control agent of bacterial leaf blight (BLB) disease. Based on the in planta screening, four endophytic bacteria that capable of controlling BLB diseases from the group of Bacillus were obtained, such as Bacillus cereus P14, Bacillus cereus Se07, Bacillus sp. HI, and Bacillus sp. SJI. The aims of this study were to investigate the characteristics of endophytic Bacillus that capable of controlling BLB disease and to determine the characteristic that most responsible in the disease control. This study method was descriptive. The characteristics observed were production of antibiotics by paper disc method, production of salicylic acid by capillary electrophoresis, and root colonization by in planta method. Linear regression analysis was used to determine the characteristic most responsible in the disease control. The results showed that four endophytic Bacillus were capable of producing salicylic acid and colonizing the root, and three of them were also capable of producing antibiotic. Salicylic acid production varied ranging from 13.96 to 14.72 ppm mL-1. Three endophytic Bacillus were capable of producing antibiotic with inhibition zone of 16.25 to 20.25 mm. Endophytic Bacillus was able to colonize the shallot roots with a population of bacteria ranged from 3.20 × 105-6, 20 × 105 CFU g-1 root. Based on the correlation coefficient of linear regression analysis, the root colonization of endophytic bacteria played the role in decreasing BLB disease.

Screening of indigenous  rhizobacteria from healthy soybean root to control bacterial pustule (Xanthomonas axonopodis pv. glycines) using in planta technique. Plant growth promoting rhizobacteria are a group of bacteria  that actively colonize plant roots, increase plant growth and control  plant pathogens. The aim of this study was to obtain rhizobacteri isolates which have the ability to control bacterial pustule and  increase growth and yield of soybean. This method based on in planta selection of enhanced competitive soil root-colonizing bacteria from soil samples of healthy soybean root at endemic area of bacterial pustule in Darmasraya  District  and   Sijunjung District, West Sumatera. We characterized only the best rhizobacteri isolates which have ability to control bacterial pustule and to increase growth and yield of soybean. This type of characterization has possibility to find  new, easy and cheap biocontrol organisms. Ten Rhizobacteri isolates were introduced via seed treatment (108 cfu/ml) and soil drench to 3 week old  soybean seedling. Xanthomonas axonopodis pv. glycines were inoculated to one month old of soybean seedling. The effect of rhizobacteria  on disease incidence, disease severity, plant growth and yield of soybean were evaluated.  We have found that two selected  rhizobacteri isolates from soybean (P12Rz2.1 and P14Rz1.1) were the best isolates in promoting growth and the of the soybean plants  with the effectiveness  20.62 % and 20.47 %.