Pseudomonas aeruginosa developed its biocontrol agent property through the production of antifungal derivatives, with the phenazine among them. In this study, the applications of crude phenazine synthesized by Pseudomonas aeruginosa UPMP3 and hexaconazole were comparatively evaluated for their effectiveness to suppress basal stem rot infection in artificially G. boninense-challenged oil palm seedlings. A glasshouse experiment under the randomized completely block design was set with the following treatments: non-inoculated seedlings, G. boninense inoculated seedlings, G. boninense inoculated seedlings with 1 mg/ml phenazine application, G. boninense inoculated seedlings with 2 mg/ml phenazine application and G. boninense inoculated seedlings with 0.048 mg/ml hexaconazole application. Seedlings were screened for disease parameters and plant vigour traits (plant height, plant fresh weight, root fresh, and dry weight, stem diameter, and total chlorophyll) at 1-to-4 month post-inoculation (mpi). The application of 2 mg/ml phenazine significantly reduced disease severity (DS) at 44% in comparison to fungicide application (DS = 67%). Plant vigour improved from 1 to 4 mpi and the rate of disease reduction in seedlings with phenazine application (2 mg/ml) was twofold greater than hexaconazole. At 4, 6 and 8 wpi, an up-regulation of chitinase and β-1,3 glucanase genes in seedlings treated with phenazine suggests the involvement of induced resistance in G. boninense-oil palm pathosystem.

Burkholderia cepacia UPMB3 is an important plant growth promoting rhizobacteria isolated from oil palm rhizosphere which is considered to promote plant growth directly or indirectly. The IAA was extracted, purified, detected and confirmed by thin layer chromatography analyses f r o m t h e strain UPMB3 of B. cepacia. Rf value was compared with the authentic IAA. Maximum 50 µg/ml IAA was produced in the medium supplemented with 4 mg/ml L-tryptophan, under shaken conditions at 150 rpm in seven days incubation at pH 7. The bacterial extract significantly influenced the growth of oil palm seedlings producing shoot, root, leaf and leaf length compared to control.

To cite this paper: Parvin, W., R. AbstractTo identify the phenazine antibiotics from the selected UPMP3 strain of Pseudomonas aeruginosa and assessment of its antagonistic activity of Ganoderma boninense, three antibiotics phenazine (PHZ), phenazine-l-carboxylic acid (PCA) and pyocyanin (PYO) were extracted from the bacterial fermented broth using benzene and chloroform and detected through High-performance liquid chromatography (HPLC). The effects of three antibiotics on suppressing mycelial growth of G. boninense were assayed. The maximum amount of PHZ, PCA and PYO were recorded as 1.36, 9.62 and 15.48 µg/mL, respectively and showed in vitro antagonistic activity against G. boninense. Phenazine was found to be more effective than PCA and PYO to inhibit the mycelial growth of G. boninense. It was 100% for PHZ at 1.0 mg/mL, while 78.61% for PCA and 91.87% for PYO after 7 days of incubation. Phenazine, PCA and PYO were identified as first time from oil palm rhizospheric UPMP3 strain of P. aeruginosa. The results indicated that the identified PHZ, PCA and PYO compound had good antifungal activity against G. boninense, however the PHZ can be developed as an ideal biofungicide for the control basal stem rot disease of oil palm and helps to overcome the concerns about the residual effects of synthetic fungicides.

A protocol has been developed for induction, maturation and germination of the zygotic embryo derived callus of the rubber tree (Hevea brasiliensis Muell. Arg.). The influence of plant growth regulators (PGRs) including 2,4-D, α-NAA, picloram, GA 3 and TDZ on MS and MMS were studied. Optimum calli were induced on MS supplemented with 2.0 mg/l 2, 4-D. The best callus growth and proliferation was recorded on MS fortified with 2.0 mg/l 2, 4-D + 2.0 mg/l BAP + 0.5 mg/l NAA. The maximum embryonic calli were induced on MS + 2.0 mg/l 2, 4-D + 2.0 mg/l Kn medium. Embryo induction, differentiation and maturation were obtained on MMS (MS +Vit B5). The rooted plantlets were produced on half strength MS without any supplements.The novelty of this study is the induction of embryos and plant regeneration from zygotic embryo explants of Hevea for the first time. The protocol developed in this study will facilitate mass propagation of high yielding rubber clones as well as to develop transgenic rubber plants with desired genes through genetic transformation.