Complete chloroplast genome comparisons for Pityopsis (Asteraceae)

Area of Science:

• Botany
• Evolutionary Biology
• Genomics

Background:

• Pityopsis, an endangered plant genus, exhibits diverse ploidy levels and ecological traits like drought tolerance and fire-dependent flowering.
• Previous phylogenetic analyses based on morphology and initial DNA sequences yielded conflicting results, leaving infrageneric relationships unresolved.

Purpose of the Study:

• To resolve the infrageneric relationships within the Pityopsis genus.
• To understand the evolutionary history and genetic basis of key ecological traits in Pityopsis.
• To provide genomic resources for conservation and breeding efforts.

Main Methods:

• Sequencing and de novo assembly of chloroplast (cp) genomes for 12 Pityopsis species.
• Construction of a maximum likelihood (ML) phylogeny based on cp genome sequences.
• Construction of an ML phylogeny using the nuclear ribosomal repeat region.

Main Results:

• The chloroplast phylogeny identified two distinct clades within Pityopsis.
• Both chloroplast and nuclear phylogenies largely contradicted previously proposed taxonomic sections and clades.
• The study generated a reference cp genome for Pityopsis falcata.

Conclusions:

• The resolved phylogenies provide a new framework for understanding Pityopsis evolution.
• Genomic data offer tools to investigate hybridity and the genetic basis of drought tolerance and fire-dependent flowering.
• Findings will aid conservation strategies and deepen knowledge of speciation within Pityopsis.