Melatonin enhances the hemiparasite Santalum album Linn. tolerance to
low nitrogen stress via accelerated N metabolism and haustoria
development
Abstract
Santalum album is a hemiparasitic plant that obtains some of its water
and nutritional requirements by parasitizing the roots of neighboring
plants. As a hemiparasite, S. album can obtain organic N from
parasitizing host roots as well as inorganic N by absorption thru its
roots. In this current study, we evaluated changes in the physiology,
transcriptional profiles and chromatin accessibility in S. album
seedlings exposed to low N conditions with and without supplemental
melatonin. We employed two complementary assays, global transcriptome
analysis (RNA-seq) and assay for transposase-accessible chromatin with
high throughput sequencing (ATAC-seq) to identify genes and genic
regions differentially regulated in S. album roots under these
conditions. Low N conditions disturbed the homeostasis of N metabolism,
reducing both N uptake and assimilation. The inclusion of melatonin
enabled S. album seedlings in low N conditions to achieve significantly
higher levels of N uptake and assimilation compared to plants without
melatonin. Interestingly, melatonin treatment also enhanced haustorium
development through a mechanism associated with auxin accumulation.
These results suggest that the application of supplemental melatonin may
accelerate N metabolism and haustorium formation of S. album in low N
conditions.