Agalinis purpurea

Figure 1. Haustorium on Agalinis purpurea 24 hours after induction. Reprinted with permission from Dr. Vance Baird.)...

While the activity and the structural specificity of the xenognosins were very encouraging, Astragalus gummifer is native to the Middle East and would not be expected to have co-evolved as a host for the southeastern U.S. native, Agalinis purpurea. The questions of whether molecules of this type were actually exuded from host roots in sufficient quantities to constitute host selection still remained. For that reason, John Steffens switched his attention to Lespedeza... 

Figure 11. Relative activities of haustorial inducers when presented in solution to 2—to-3 week-old plants of Agalinis purpurea. Plants developed an average gf two haustoria each when presented with xenognosin A at 10 M.(13).

Steffens, J.C. et al., Molecular specificity of haustorial induction in Agalinis purpurea (L.) Raf. 

The haustorial inducer from Lespedeza sericea for the parasite Agalinis purpurea, however, proved to be a triterpene, soyasapogenol B (Lynn, 1985). 

As the roots of parasitic plants attach to those of the host plant, a special structure, Ae haustorium, is formed. The formation of haustoria in induced by exudates from the host plant. When the roots of the Agalinis purpurea... 

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