ABSTRACT

Auxin, a plant growth-promoting hormone, is known to be produced by many if not all bacteria. Research has shown that bacteria produced auxin is associated with both positive and negative plant growth effects. Here we determined the relationship between auxin production capacity and wheat biomass productivity in culturally isolated bacteria. A total of 4320 individual bacteria were isolated and characterized based on colony size as either fast (>2 mm) or slow (<2 mm) growing, from the rhizospheres and endorhizospheres of wheat plants grown in two soils that differ in pH and texture. The bacteria were assayed for auxin production based on a Salkowski reagent microplate assay. The relationship between auxin production and wheat biomass was largely negative under all conditions and characterizations, and non-significant (R² 0.04 to 0.26). When examined across all treatments, the lowest auxin producers originated from the highest biomass plants and the highest auxin producers from the lowest biomass plants (p value < .0001). Fast growing colonies produced significantly higher auxin production than slow growing colonies, overall (p value ≤ 0.005). The results suggest that auxin production by culturally isolated bacteria, as determined by the Salkowski reagent, is negatively associated with wheat biomass productivity.

摘要

生长素，一种植物生长促进激素，已知是由许多细菌产生的，即使不是全部细菌也可以产生。研究表明，细菌产生的生长素与植物的正负生长作用有关。在这里，我们确定了分离培养细菌中生长素的生产能力与小麦生物量生产率之间的关系。从在两种pH和质地不同的土壤中生长的小麦植株的根际和根际中分离出总共4320种细菌，并根据菌落大小将其表征为快速生长（> 2 mm）或缓慢生长（<2 mm）。基于Salkowski试剂微孔板测定法分析细菌的生长素产生。生长素产量与小麦生物量之间的关系在所有条件和特征下均呈负相关，且无显着性（R ²0.04至0.26）。在所有处理中进行检查时，最低的植物生长素产生者来自最高的生物量植物，最高的植物生长素产生者来自最低的生物量植物（p值<.0001）。总体而言，快速生长的菌落产生的生长素产量明显高于缓慢生长的菌落（p值≤0.005）。结果表明，由Salkowski试剂确定的文化分离细菌产生的植物生长素与小麦生物量生产力呈负相关。