Abstract Detail

Comparative Genomics/Transcriptomics

Charboneau, Joseph [1], Cronn, Richard [2], Liston, Aaron [3], Wojciechowski, Martin [4], Sanderson, Michael [5].

Plastome Structural Evolution in Neo-Astragalus (Astragalus L., Fabaceae).

Unlike the vast majority of land plant plastid genomes, the plastomes of species in the inverted-repeat lacking clade of legumes (IRLC; Fabaceae) have only one copy of the inverted repeat. Species in several genera within the IRLC have also been found to have rearranged plastomes through large-scale inversions, and short repeated sequences have been found near the endpoints of plastome inversions in many groups of plants. We sequenced and assembled the plastomes of 25 taxa of Astragalus L., the largest genus in the IRLC (and of seed plants) to better understand any connection between short repeats and plastome inversions. We found a strong phylogenetic signal in plastome repeat structure among these closely related taxa mostly in the New World clade of Astragalus (Neo-Astragalus). Four of the sequenced taxa had one large plastome inversion each, and we found overall repeat structure does not differ substantially between these four taxa and those without large inversions. Two of the taxa had inversions with endpoints between the same pairs of loci, but close examination of their exact endpoint locations and the repeated sequences putatively involved in the inversions indicates these two inversions occurred independently. We have also proposed a mechanism of inversion formation via microhomologous sequences that suggests some repeats found near both endpoints of plastome inversions are there as a result of the inversions and did not cause them

1 - University Of Arizona, Department Of Ecology And Evolutionary Biology, 1041 E. Lowell St., Tucson, AZ, 85721, United States
2 - USDA Forest Service, 3200 SW Jefferson Way, Corvallis, OR, 97330, United States
3 - Oregon State University, Department Of Botany & Plant Pathology, 2082 Cordley Hall, Corvallis, OR, 97331, United States
4 - Arizona State University, School Of Life Sciences, PO Box 874501, Tempe, AZ, 85287, United States
5 - University Of Arizona, Ecology And Evolutionary Biology, Tucson, AZ, 85749.0, United States

Keywords:
Chloroplast genome
Leguminosae
inverted repeat-lacking clade
inversion mechanisms.

Presentation Type: Oral Paper
Number: CGT4004
Abstract ID:875
Candidate for Awards:Margaret Menzel Award