| Nod factors are lipochito-oligosaccharide signal molecules secreted by soil-living rhizobia. These molecules elicit a range of responses in the legume roots, by which the bacteria can live in symbiosis. The root hair deformation is probably one of the best-characterized biological activities of application of purified Nod factors.Medicago sativa, a legume plant that is specifically interacted with nodule bacterium Sinorhizobium meliloti for root nodulation, was used as the model plant in this research work. The occurrence of Nod factors-induced root hair deformation was used to study the influence of factors on this process. The Nod factors were isolated and partially purified using HPLC technique. The root hair deformation depended on external Ca2+. In the absence of external Ca2+, Nod factors didn't induce root hair deformation. Moreover, high external Ca2+ was able to mimic Nod factor-induced root hair deformation without addition of Nod factors in external medium. The Nod factors-induced root hair deformation was attenuated by the use of actin-depolymerizing drug latrunculin A. Furthermore, high external concentration of Ca2+ reversed the influence of depolymerization of the actin filament. In order to simultaneously examine the dynamics of tip cytosolic Ca2+ and the dynamics of tip-localized F-actin in vivo, double fluorescence-labeled material was constructed.
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