Histological and biochemical evaluation of Santalum album L. seedlings cocultivated with different hosts

Abstract

S. album establishes haustorial connections with the roots of specific hosts to fulfill its nutritional requirements during the primary stages of growth. Haustoria are the specialized structures having meristematic cells establishing an inverted flask shaped vascular connection with host stele for the transport of nutrients. In the present study we examined the morphological and  anatomical features along with biochemical parameters of sandal haustoria developed with the roots of five host species from  leguminous (M. pudica L., C. ternatea L., C. pubescens Benth. and  A. glabrata Benth.) and non-leguminous (V. zizanioides (Linn.) Nash) plants. Sandal plants also showed auto-parasitism or intraspecific parasitism. The plants attached with the roots of M. pudica showed better growth (total chlorophyll, protein and carbohydrate content) compared to sandal plants attached with other hosts. Number and size of haustoria were more on the roots of sandal attached with Mimosa roots, but it was less in sandal attached with Vetiveria roots. Histologically sandal haustorium has a hyaline body on the periphery of host roots and a penetration peg which penetrates into the host tissue and formed a laterally flattened ellipsoidal disc at the cortex of host root. A thick mass of parenchyma was present at the interface of haustorium and host xylem.  Red secretions were observed at the interface region where a thick mass of haustorial parenchyma attached with xylem tissues of the host. Haustorial xylem to host xylem connections at the interface region were prominent in sandal attached with Mimosa, but haustorial parenchyma to host xylem connections at the interface region were prominent when sandal attached with other hosts. Irregularly shaped penetration peg was present in V. zizanioides which intruded into the host root xylem pith. In the present study we focused on the impact leguminous and non-leguminous primary hosts on sandal plants and their influences on growth parameters, which give important information for further studies.