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Logo of biotbiofuelBioMed CentralBiomed Central Web Sitesearchsubmit a manuscriptregisterthis articleBiotechnology for Biofuels
 
Biotechnol Biofuels. 2012; 5: 37.
Published online May 30, 2012. doi:  10.1186/1754-6834-5-37
PMCID: PMC3462104
Growth promotion and colonization of switchgrass (Panicum virgatum) cv. Alamo by bacterial endophyte Burkholderia phytofirmans strain PsJN
Seonhwa Kim,1 Scott Lowman,1,2 Guichuan Hou,4 Jerzy Nowak,2 Barry Flinn,1,2,3 and Chuansheng Meicorresponding author1,2,3
1Institute for Sustainable and Renewable Resource, Institute for Advanced Learning and Research, 150 Slayton Ave, Danville, VA, 24540, USA
2Department of Horticulture, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24601, USA
3Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24601, USA
4The Dewel Microscopy Facility at the College of Arts and Sciences, Appalachian State University, Boone, NC, 28608, USA
corresponding authorCorresponding author.
Seonhwa Kim: seonhwa.kim/at/ialr.org; Scott Lowman: scott.lowman/at/ialr.org; Guichuan Hou: houg/at/appstate.edu; Jerzy Nowak: jenowak/at/vt.edu; Barry Flinn: barry.flinn/at/ialr.org; Chuansheng Mei: chuansheng.mei/at/ialr.org
Received March 26, 2012; Accepted May 10, 2012.
Abstract
Background
Switchgrass is one of the most promising bioenergy crop candidates for the US. It gives relatively high biomass yield and can grow on marginal lands. However, its yields vary from year to year and from location to location. Thus it is imperative to develop a low input and sustainable switchgrass feedstock production system. One of the most feasible ways to increase biomass yields is to harness benefits of microbial endophytes.
Results
We demonstrate that one of the most studied plant growth promoting bacterial endophytes, Burkholderia phytofirmans strain PsJN, is able to colonize and significantly promote growth of switchgrass cv. Alamo under in vitro, growth chamber, and greenhouse conditions. In several in vitro experiments, the average fresh weight of PsJN-inoculated plants was approximately 50% higher than non-inoculated plants. When one-month-old seedlings were grown in a growth chamber for 30 days, the PsJN-inoculated Alamo plants had significantly higher shoot and root biomass compared to controls. Biomass yield (dry weight) averaged from five experiments was 54.1% higher in the inoculated treatment compared to non-inoculated control. Similar results were obtained in greenhouse experiments with transplants grown in 4-gallon pots for two months. The inoculated plants exhibited more early tillers and persistent growth vigor with 48.6% higher biomass than controls. We also found that PsJN could significantly promote growth of switchgrass cv. Alamo under sub-optimal conditions. However, PsJN-mediated growth promotion in switchgrass is genotype specific.
Conclusions
Our results show B. phytofirmans strain PsJN significantly promotes growth of switchgrass cv. Alamo under different conditions, especially in the early growth stages leading to enhanced production of tillers. This phenomenon may benefit switchgrass establishment in the first year. Moreover, PsJN significantly stimulated growth of switchgrass cv. Alamo under sub-optimal conditions, indicating that the use of the beneficial bacterial endophytes may boost switchgrass growth on marginal lands and significantly contribute to the development of a low input and sustainable feedstock production system.
Keywords: Bacterial endophyte, Burkholderia phytofirmans strain PsJN, Colonization, Growth promotion, Biomass increase, Switchgrass cv. Alamo
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