Institute for Sustainable and Renewable Resource, Institute for Advanced Learning and Research, 150 Slayton Ave, Danville, VA, 24540, USA.
Biotechnol Biofuels. 2012 May 30;5(1):37. doi: 10.1186/1754-6834-5-37.
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.
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.
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.
柳枝稷是美国最有前途的生物能源作物候选品种之一。它的生物量产量相对较高，能够在边际土地上生长。然而，它的产量会因年份和地点的不同而有所变化。因此，开发一种低投入和可持续的柳枝稷原料生产系统是当务之急。增加生物量产量的最可行方法之一是利用微生物内生菌的益处。
我们证明，最受研究的植物生长促进细菌内生菌之一，鲍氏不动杆菌菌株 PsJN，能够在体外、生长室和温室条件下定殖并显著促进柳枝稷 cv.Alamo 的生长。在几项体外实验中，接种 PsJN 的植物的平均鲜重比未接种的植物高出约 50%。当一个月大的幼苗在生长室中生长 30 天时，接种 PsJN 的 Alamo 植物的地上部和根生物量明显高于对照。五个实验的平均生物量（干重）在接种处理中比未接种对照高出 54.1%。在温室实验中，将移栽植物种植在 4 加仑的盆中两个月后也得到了类似的结果。接种植物表现出更多的早期分蘖和持续的生长活力，生物量比对照高出 48.6%。我们还发现，PsJN 可以显著促进柳枝稷 cv.Alamo 在次优条件下的生长。然而，PsJN 介导的柳枝稷 cv.Alamo 生长促进作用是基因型特异的。
我们的结果表明，鲍氏不动杆菌菌株 PsJN 显著促进了柳枝稷 cv.Alamo 在不同条件下的生长，特别是在早期生长阶段，从而增加了分蘖的产生。这种现象可能有利于柳枝稷在第一年的建立。此外，PsJN 显著刺激了柳枝稷 cv.Alamo 在次优条件下的生长，表明有益的细菌内生菌的使用可以促进柳枝稷在边际土地上的生长，并为低投入和可持续的原料生产系统的发展做出重大贡献。
