Studies on the Roots of Musa acuminata cv. Gros Michel: 1. The Anatomy and Development of Main Roots

The anatomy of the adventitious roots of Musa acuminata cv.Gros Michel is described. Interesting anatomical features arethe occurrence of lysigenous lacunae in the cortex and the presenceof very large metaxylem vessels and internal phloem strandsin the stele. The organization of the root meristem is consideredin terms of present concepts. Histological preparations andautoradiographs suggest the existence of an area of relativequiescence in the meristem. The use of modified histogen terminologyin describing the apex is recommended. The development of thetissue systems is also described with emphasis on the differentiationof the vascular tissue.     

Molecular Specificity of Haustorial Induction in Agalinis purpurea (L.) Raf. (Scrophulariaceae)

An exogenous signal normally contained in host root exudateis required for initiation of the haustorium by the root parasiteAgalinis purpurea (L.) Raf. (Scrophulariaceae). Two flavonoidsthat induce haustoria have been isolated from gum tragacanthand a number of structural analogues have been synthesized.The results show that a high degree of molecular specificityis required for haustorial induction. Both isolated flavonoidscontain substituted 3-methoxyphenol functionality, and syntheticanalogues have shown that 4-substituted 3-methoxyphenol functionalityis critical for high levels of haustorial induction. These dataprovide a model for understanding host recognition at the levelof haustorial induction in parasitic angiosperms. Agalinis purpurea (L.) Raf. Scrophulariaceae, haustorial induction, flavonoids, molecular specificity, parasitic angiosperms, xenognosin