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PRESENCE OF RHIZOBIA IN THE XYLARY ELEMENTS OF ROOT NODULES IN SAMANEA SAMAN (JACQ.) MERR.

RAIHA QADRI AND A. MAHMOOD

Abstract: The paper reports the morphogenesis and anatomy of root nodules. The nodules were distributed singly as well as in clusters on the main and lateral roots of Samanea saman (Jacq.) Merr. Young nodules were globose whereas mature nodules were elongated, branched and coralloid. Rhizobia entered the root via root hair and formed infection thread. An interesting character was observed in the young nodules of S. saman where bacteria entered through the root hair and multiplied within the epidermal cell. From there they invaded into the cortical region by intracellular movement by dissolving middle lamella. Presence of bacteria inside, and their movement through xylary elements is being reported for the first time in a tree legume.

Department of Botany, University of Karachi, Karachi-75270, Pakistan.