Abstract Detail

Molecular Ecology and Evolution

Hawkins, Angela K. [1], Pepper, Alan E. [2].

Adaptation to extreme environments: Transcriptome comparisons of the serpentine endemic Caulanthus amplexicaulis var. barbarae and its non-serpentine sister species,C. amplexicaulis.

Serpentine outcrops are derived from ultramafic rock and usually have extremely low levels of essential plant nutrients (e.g. N, P, Ca), very high to toxic levels of heavy metals (e.g. Ni), and very poor water availability and retention. These outcrops provide habitat to many endemic plant species but have a patchy distribution. Serpentine soils have long been considered an ideal model system for plant molecular ecology as they offer an extreme example of adaptation to environment. Caulanthus amplexicaulis var. barbarae (J. Howell) Munz (CAB) is a wild relative of Arabidopsis thaliana (L.) Heynh and is endemic to serpentine outcrops. Its sister species, C. amplexicaulis var. amplexicaulis S. Watson (CAA), is predominately found on granite soils and, in reciprocal growth experiments, has demonstrated 100% mortality when grown in serpentine-like conditions. Using both ecologically distinct parents, normalized transcriptome libraries were constructed and assembled, providing reference sequences for future RNA-seq experiments and molecular evidence for functional annotation of the CAB whole-genome sequencing project (in progress with the DOE Joint Genome Institute). Reciprocal best-hits BLAST was used to identify putative orthologs between CAA and CAB. PAML was used to calculate dN/dS ratio to obtain support for purifying or stabilizing selection. Genes that appear to be duplicated in CAA and CAB as compared to A. thaliana were identified. Together, with data obtained from the draft genome assemblies of both taxa, a set of candidate genes inferring serpentine tolerance were identified.

1 - Texas A & M University, Biological Sciences, Texas A&M University Dept. Of Biology, 3258 TAMUS, College Station, TX, 77843-3258, USA
2 - Department Of Biology, Texas A&M University, TAMUS 3258, College Station, TX, 77843, USA

Keywords:
serpentine
Brassicaceae
Transcriptome
extreme
Caulanthus.

Presentation Type: Oral Paper:Papers for Topics
Session: 61
Location: Salon 15/16/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 10:45 AM
Number: 61011
Abstract ID:1302
Candidate for Awards:Margaret Menzel Award