Santalum album–Host Plants Interaction: An Incomplete Story of Semi-Root Parasite

Sandal (Santalum album L.) is one of the most valuable hemiparasitic tree species cultivated for its scented heartwood and oil. The economic yield from sandal depends on the hosts associated with it. Previous studies show that the sandal–host interaction is related to certain physiological, genetic and molecular mechanisms that enable them to identify host plants, to grow invasively into the hosts, and to establish connections to withdraw water and other resources from the hosts. However, the understanding of these mechanisms is still very vague. Our observations from the three-month-old sandal seedlings–host interaction study revealed the complex and multifaceted character of the host–parasite signalling mechanism. Besides, we found numerous unsolved questions and a significant knowledge gap in this field. Therefore, this article aims to correlate and contrast our observations with previous findings and to deliver some key questions to bridge the knowledge gap in future research.