Endophytic Streptomyces spp. as Biocontrol Agents of Rice Bacterial Leaf Blight Pathogen (Xanthomonas oryzae pv. oryzae)

Abstract

Xanthomonas oryzae pv. oryzae (Xoo), a causal agent of bacterial leaf blight (BLB), is one of the most important pathogens of rice. The effectiveness of ten Streptomyces spp. isolates in suppressing Xoo disease was assessed in planta and in vitro. In planta experiments were carried out in a greenhouse and arranged in a randomized completely block design (RCBD) with three replications. Twenty treatments were tested which included plants inoculated with both Streptomyces spp. and Xoo, and plants inoculated with only Streptomyces spp. Plants inoculated with Xoo and sprayed with a chemical bactericide, and plants inoculated with only Xoo served as positive controls, whereas plants not inoculated with either Streptomyces spp. or Xoo were used as negative controls. The results showed that the effect of endophytic Streptomyces spp. on BLB disease expressed as area under disease progress curve (AUDPC) was not significantly different to that on control plants (P > 0.05). However, plants inoculated with endophytic Streptomyces spp. were significantly taller and produced higher tiller number than control plants (P < 0.05). Streptomyces spp. isolate AB131-1 gave the highest plant height. In vitro studies on biocontrol mechanisms of selected Streptomyces spp. isolates showed that isolate LBR02 gave the highest inhibition activity on Xoo growth, followed by AB131-1 and AB131-2. Two isolates (AB131-1 and LBR02) were able to produce chitinase, phosphatase, and siderophore which included biocontrol characteristics. Morphological and colonization studies under SEM and light microscopy confirmed that the three isolates were endophytic Streptomyces spp. from different species. These studies found that the paddy plant which was inoculated with endophytic Streptomyces spp. AB131-1 and infected by Xoo could increase the height of plant and number of tillers.

Eksplorasi dan Karakterisasi Bakteri Agens Hayati dari Imperata cylindrica untuk pengendalian Rigidoporus microporus

“…Suspensi bakteri diinfiltrasikan pada daun tembakau. Reaksi hipersensitif diamati pada 24-48 jam setelah inokulasi (Schaad et al 2001) Tabel 3 Daya hambat bakteri dari Imperata cylindrica terhadap Rigidoporus microporus dapat digunakan untuk mendeteksi adanya mekanisme antibiosis yang terjadi pada aktivitas pengendalian oleh agens hayati (Munif et al 2012;Hastuti 2012;Khaerani et al 2012). Antibiosis adalah penghambatan satu atau lebih organisme oleh senyawa bioaktif berupa antibiotik, enzim pendegradasi dinding sel, atau senyawa volatil yang diproduksi oleh organisme lain.…”

Pelet Bakteri Probiotik untuk Biokontrol Xanthomonas oryzae pv. oryzae dan Viabilitas Benih Padi

“…Penghambatan patogen X. oryzae pv. oryzae oleh bakteri probiotik R. pickettii TT47 diduga terkait dengan kemampuan bakteri (Hastuti et al 2012) serta produksi siderofor, enzim fosfatase, enzim peroksidase dan HCN oleh P. diminuta A6 (Agustiansyah et al 2013). Pelet yang mengandung bakteri probiotik mampu mempertahankan viabilitas benih padi terinfeksi X. oryzae pv.…”

Suppressing activity of staurosporine from Streptomyces sp. MJM4426 against rice bacterial blight disease

“…Recently, an endophytic Streptomyces strain showed its biocontrol ability against rice bacterial leaf blight by inhibition of Xoo growth, but the active compound was not characterized (Hastuti et al . ). Moreover, Streptomyces toxytricini VN08‐A‐12 was selected from 2690 Actinomycetes strains by strong inhibitory activities against the growth of different races of Xoo .…”

“…Although several studies have been focused on induction of plant defence mechanism for biocontrol of fungal disease (Zhao et al 2012;Palaniyandi et al 2013b), none has been reported in biological control of Xoo by indirect mechanism. Recently, an endophytic Streptomyces strain showed its biocontrol ability against rice bacterial leaf blight by inhibition of Xoo growth, but the active compound was not characterized (Hastuti et al 2012). Moreover, Streptomyces toxytricini VN08-A-12 was selected from 2690 Actinomycetes strains by strong inhibitory activities against the growth of different races of Xoo.…”