TY  - BOOK
AU  - Garggi, C
AU  - Girija, T (Guide)
TI  - Physiological and molecular studies on genera of loranthaceae and their management 
U1  - 571.2 
PY  - 2021///
CY  - Vellanikkara 
PB  - Department of Plant Physiology, College of Agriculture 
KW  - Plant Physiology
KW  - Loranthaceae
KW  - Photosynthetic rate
KW  - Transpiration rate
KW  - Defoliation
N1  - PhD
N2  - Hemiparasitic plants belonging to the family Loranthaceae are major tree 
parasites. Dendrophthoe falcata, Helicanthus elastica, Macrosolen capitellatus are 
major hemiparasites infecting perennial crops of the tropics. Helixanthera 
wallichiana and Taxillus tomentosus are two important hemiparasites infecting the 
fruit and timber trees of the high ranges. Apart from being a troublesome parasite 
they also serve as a linchpin reservoir supporting an extensive ecosystem. The 
prevailing investigation namely “Physiological and molecular studies on genera of 
Loranthaceae and their management” was carried out at Department of Plant 
Physiology, College of Agriculture, Vellanikkara, Thrissur, during the period from 
2015 to 2020.
 Morphological characters of representative species viz., Dendrophthoe falcata, 
Helicanthus elastica, Macrosolen capitellatus, Helixanthera wallichiana and Taxillus 
tomentosus from five selected. Samples of these were collected from various 
locations from the plains and highranges of Thrissur. In all the selected species, 
leaves were oppositely arranged, D. falcata and H. elastica had oblong shaped leaves, 
leaves of M. capitellatus was lanceolate in shape, and H. wallichiana and T. 
tomentosus had narrow ovate shaped leaves. Fruit was berry in all the genera.
Hemiparasites possess a physiological structure called haustoria through which they 
abstract water and minerals from the host. Haustorial branching pattern in all the 
genera was found to be basal epicortical root (ber). Haustorial portions of the 
collected samples were treated and prepared to permanent slides. Anatomical sections 
of the haustoria of the five selected genera of Loranthaceae revealed that there exists 
a transition zone between the host- parasite interphase region. This was observed as 
undifferentiated parenchymatous cells which aid in translocation of molecules. 
Presence of xylem elements were observed at the haustorial region. Haustorial 
anatomy of M. capitellatus was unique as there was complete merging of cells of host 
and parasite at the interphase region.
 The lineage of five selected genera belonging to Loranthaceae family were 
studied by molecular assay. The results from the ISSR assay revealed that, T. 
tomentosus and M. capitellatus had maximum similarity compared to all the other 
genera, since it formed a separate cluster. Morphological characterization indicated 
similarity between the two genera in the haustorial attachment pattern. Both the 
species have a single point of attachment to the host. H. wallichiana was observed to 
be more similar to the first cluster. D. falcata formed another branch close to H. 
wallichiana, where all these four genera formed the main group. H. elastica formed a 
separate lone group, which indicated genetical variance from other genera studied. 
Morphological observations supporting such a uniqueness in this parasite was noted
in haustorial branching type, where basal epicortical root with lateral tendril like 
structures from nodes and internodes were observed. The parasite also showed other 
phylogenetically advanced characters according to Angiosperm Phylogeny Group 
(APG system) of classification like fused corolla and calyx.
To study the host parasite interaction, root feeding studies with labelled 32P 
were undertaken. Cocoa plants infected with both parasites D. falcata and H. elastica 
was selected for the study. 32P in carrier solution of 1000ppm orthophosphoric acid @ 
2 mCi per plant was fed to the surface running roots of cocoa. Leaf samples of the 
host and parasite were collected at 7 and 14 days after treatment and assayed for radio 
activity. To understand the translocation from parasite to host, leaves of the parasitic 
species both D. falcate and H. elastica were also smeared with labelled 32P and leaf 
samples were analysed from different parts of both the host and the parasite. These 
experiments were done on different trees. Leaf samples of the host and parasite were 
collected at 2, 7 and 14 DAT and assayed for radio activity. Results from the radio 
assay indicated that there is bidirectional movement of nutrients from host to parasite 
and parasite to host. There exists a prioritized partitioning pattern for nutrient 
transport (phosphorous) based on demand by the sink, regardless of the parent plant. 
The host and parasite were found to act as a single system indicating their coexistence.
 Physiological parameters of the host and parasites were also observed using InfraRed Gas Analyser (IRGA) for a period of six months. It was observed that stomatal 
conductivity of D. falcata and H. elastica was significantly higher than the host 
cocoa. Even though there was no much variation in the photosynthetically active 
radiation (PAR) received by the host and parasite during the period of observation, D. 
falcata and H. elastica had significantly higher rate of photosynthesis than cocoa. 
Transpiration rate of both parasites were significantly higher than their host. 
Carboxylation efficiency and light use efficiency of H. elastica were observed to be 
significantly higher than the host, cocoa.
 Field experiment was conducted to improve the management strategy and control 
the spread of the parasite. Use of surfactant was found to improve the efficacy of 
ethephon in controlling the regrowth of parasite on host plant. Non- ionic surfactants 
viz., Nonyl phenol ethoxylate (NPE) and Organosilicone (OS) were selected for the 
study. A combination of OS (0.5 ml/L) surfactant with ethephon (25ml/L) was 
successful in suppressing the regrowth of both D. falcata and H. elastica
UR  - https://krishikosh.egranth.ac.in/handle/1/5810190143
ER  -