Influence Of Herbaspirillum Seropedicae (Z78) On Calli, Embryogenic Calli And Plantlets Of Oil Palm Clone P614d
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Date
2017-03
Authors
Lim, Shey Li
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
A continuous discovery of novel practices for in vitro plant culture is always essential to promote better plant growth in the shortest cultivation period. An alternative approach for conventional micropropagation practice could be achieved through biotization by inoculating selected diazotrophs to the plant materials. Recently, interest in artificial symbiosis through the application of diazotrophic bacteria onto host plant is increasing in order to gain a better insight of the symbiotic mechanism. This study was conducted to observe the effects of Herbaspirillum seropedicae (Z78) on growth of calli, embryogenic calli and plantlets of oil palm fruit forms Dura (clone P614D). A total of four treatments were tested for calli and embryogenic calli of oil palm on modified Murashige and Skoog medium for 60 days of cultivation, namely: T1: 100 % (w/v) nitrogen source + 100 % (w/v) 2,4-D; T2: 25 % (w/v) nitrogen source + 10 % (w/v) 2,4-D; T3: Z78 sonicated cells + 25 % (w/v) nitrogen source + 10 % (w/v) 2,4-D and T4: Z78 pellet cells + 25 % (w/v) nitrogen source + 10 % (w/v) 2,4-D. Total phenolics, total amino acids, total proteins and total sugars were examined every 10 days interval for 60 days cultivation of calli and embryogenic calli, respectively. Plantlets were treated with: T1:100 % (w/v) nitrogen source; T2: 25 % (w/v) nitrogen source; T3: Z78 sonicated cells + 25 % (w/v) nitrogen source; T4: Z78 broth culture + 25 % (w/v) nitrogen source and T5: Z78 pellet cells + 25 % (w/v) nitrogen source. All treatments were supplied with 100 % potassium and phosphorous. The outcome of amplified nifH gene fragment for Herbaspirillum seropedicae was successfully proven Z78 as a nitrogen fixing bacteria harbouring nifH gene to encode the nitrogenase structural proteins. Through this study, an artificial symbiosis was successfully established for Herbaspirillum seropedicae (Z78) with calli, embryogenic calli and in vitro plantlets of oil palm. Microscopy observation also proved the symbiosis activities of epiphytic and endophytic in the bacterium-callus and embryogenic callus colonization. Chromatography analysis demonstrated the presence of indole-3-acetic acid (IAA) and nitrogenase enzyme activities for free living Herbaspirillum seropedicae and in associated conditions. These results indicate the significant effect of Z78 pellet cells in biomass increment, nitrogen fixation activities and indole-3-actic acid production in treated calli. Calli proliferation was also significantly observed on Z78 pellet cells (T4) while embryoid formation was observed for embryogenic calli treated with Z78 sonicated cells (T3). The plantlets treated with Z78 broth culture promoted better growth profile compared to plantlets treated with 25% (w/v) nitrogen source. The broth culture of Z78 inoculation showed significant difference on root volume, indole-3-acetic-acid production, total protein content, Brix value and acetylene reduction assay in comparison to plantlets treated with 25% (w/v) nitorgen source (T2). The results of this study supported by the hypothesis that bacteria Z78 was a high potential diazotroph having the ability to enhance the growth of in vitro oil palm cultures under minimal supply of nitrogen.
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Keywords
Influence Of Herbaspirillum Seropedicae (Z78) On Calli , Embryogenic Calli And Plantlets Of Oil Palm Clone p614d