Justicia adhatoda reveals two morphotypes with possible functional significance

Area of Science:

• Botany
• Plant Taxonomy
• Ecology

Background:

• Justicia adhatoda L. (Acanthaceae) is widespread in India.
• Indian botanists have used synonyms Adhatoda vasica and Adhatoda zeylanica, often treating them as separate species without acknowledging variation.
• Previous studies have not addressed the potential for distinct forms within J. adhatoda populations.

Purpose of the Study:

• To investigate phenotypic, genotypic, and distributional variations in Indian Justicia adhatoda populations.
• To determine if recognized synonyms represent distinguishable forms of the species.
• To assess the adaptive significance of observed variations.

Main Methods:

• Field studies across diverse Indian regions.
• Laboratory analysis of phenotypic traits (anatomical, biochemical, reproductive, morphometric).
• Preliminary genetic variation study using cytochrome P450 gene fragments.
• Assessment of herbarium specimens and taxonomic literature.

Main Results:

• Population-level variation revealed two distinct morphotypes of Justicia adhatoda.
• These morphotypes show a tendency to occur in dry and wet regions, respectively.
• Both morphotypes maintained their distinct phenotypes when transplanted, indicating stable genetic differences.
• Morphological and metabolic profiling suggests adaptation to different moisture levels.
• These forms were identifiable in herbarium specimens dating back to 1821, but were not previously described.

Conclusions:

• The study proposes recognizing two distinct morphotypes within Justicia adhatoda.
• These morphotypes exhibit adaptations to contrasting environmental conditions (dry vs. wet).
• The findings challenge previous taxonomic treatments and highlight the importance of considering intraspecific variation.