Anatomy and Functional Status of Haustoria in Field Grown Sandalwood Tree (<i>Santalum album</i> L.)

Abstract

A study on the physiology of root parasitism in sandal (Santalum album L.) was conducted by comparing a six-year-old sandal grown alone and along with a host (Casuarina equisetifolia). Although maximum haustorial connections were observed when grown along with the host, sandal formed haustorial connections with plants including grass up to a distance of 3 m. Anatomical studies on haustoria indicated a vascular connectivity between the host and sandal. While the haustoria functioned as a physiological unit supporting nutritional requirements of sandal, direct lumenlumen xylem connections between sandal and host were absent. Functional status of the haustorial connection was studied by radio-labelling the host (Casuarina) and nearby grass with phosphorus ( 32 P). Presence of translocated 32 P in sandal was noticed after six hours of labelling the host. 32 P activity was noticed from eight days up to 16 days after which then it started decreasing. Study with multiple hosts revealed that the extent of translocation from hosts to sandal varied from 28.9% (coconut + Casuarina + rubber as host) to 78.5% (Casuarina + rubber as hosts). Reverse translocation of 32 P from sandal to host was also observed. The study concludes that it is not necessary to plant the host along with the sandal as it is practiced presently.

Domestication provides the key to conservation ofSantalum yasi– a threatened Pacific sandalwood

“…Like all other sandalwood species, S. yasi establishes root connections with one or more host plants via root haustoria (Ouyang et al 2016;Rocha et al 2017). The growth and survival of individual sandalwood trees is strongly dependent on the suitability, arrangement and vigour of the host (Radomiljac et al 1999;Brand 2009;da Silva et al 2016).…”

Host Plant Modulated Physio-Biochemical Process Enhances Adaptive Response of Sandalwood (Santalum album L.) under Salinity Stress

“…Simultaneously, salinity can cause cellular oxidative damage and interfere with a variety of cellular functions, including photosynthesis, respiration, plasma membrane function, and turgor loss due to the lower water potential [ 41 ]. Under stress conditions, sandalwood maintains the water status by either accumulating osmotically active chemicals or establishing direct xylem-to-xylem connections with host plants [ 46 , 47 , 48 ]. In addition, the lowering of ψ p , ψ s , and RWC played a protective role by maintaining osmolyte accumulation, stomatal conductance, turgor pressure, thereby safeguarding macromolecules (such as membranes, chloroplast, and proteins) and their structural integrity from damage caused by stress and facilitating sandalwood adaptability [ 49 , 50 , 51 ].…”

Host–parasite interaction: an insight into the growth and physiological responses of sandalwood and associated host species

“…Whistling pine Casuarinaceae Nagaveni and Vijayalakshmi (2003), Padmanabha et al (1988), Rocha et al (2014Rocha et al ( , 2017…”

“…Sandalwood has been found parasitizing on a wide range of plants (300 species) ranging from grasses to trees (Nagaveni and Vijayalakshmi, 2003). Among the host species, Azadirachta indica (Nagaveni and Vijayalakshmi, 2003), Dalbergia latifolia and Syzygium cumini (Guleria, 2013), Acacia nilotica and Melia dubia (Padmanabha et al, 1988), Leucaena leucocephala (Guleria, 2013), Casuarina equisetifolia (Nagaveni and Vijayalakshmi, 2003;Rocha et al, 2014), and Acacia hemignosta, A. ampliceps, and Melia azedarach (Radomiljac et al, 1998) were observed to be the most suitable host tree species in terms of maintaining the growth as well as biomass accumulation of sandalwood, but there is a dearth of knowledge regarding the physiological responses of sandalwood to diverse host species. Simultaneously, during the parasitism process, several growth and physiological alterations occur in the host species (Rocha et al, 2014), and at present, information about such is completely lacking.…”

“…Among the host species, Azadirachta indica (Nagaveni and Vijayalakshmi, 2003), Dalbergia latifolia and Syzygium cumini (Guleria, 2013), Acacia nilotica and Melia dubia (Padmanabha et al, 1988), Leucaena leucocephala (Guleria, 2013), Casuarina equisetifolia (Nagaveni and Vijayalakshmi, 2003;Rocha et al, 2014), and Acacia hemignosta, A. ampliceps, and Melia azedarach (Radomiljac et al, 1998) were observed to be the most suitable host tree species in terms of maintaining the growth as well as biomass accumulation of sandalwood, but there is a dearth of knowledge regarding the physiological responses of sandalwood to diverse host species. Simultaneously, during the parasitism process, several growth and physiological alterations occur in the host species (Rocha et al, 2014), and at present, information about such is completely lacking. Moreover, parasite sandalwood induces several growth and physiological alterations in host species, which is one of the main hindrances in the successful establishment of sandalwood plantations; however, no systematic information on such interaction is available.…”