Abstract Detail

Donald J. Pinkava's legacy - the ASU Herbarium in the Sonoran Desert

Wojciechowski, Martin [1], Alt, Austin [2], Hopkins, Andrew [3], Majure, Lucas [4], Steele, Kelly [5], Sanderson, Michael [6].

Plastid genome evolution in Cactaceae: emerging patterns of gene and inverted repeat losses and rearrangements.

The Cactaceae, a diverse family of angiosperms that evolved about ~35 million years ago, is the most evolutionarily successful adaptive radiation of succulent plants distributed in arid and semi-arid regions of the New World. Cacti are remarkable for extreme succulence in most members, their diversity of growth forms, and possession of a Crassulacean Acid Metabolism mode of photosynthesis. We previously found the plastid genomes of the saguaro, Carnegiea gigantea, and several closely related North American columnar species, have been reduced in size by the loss or pseudogenization of most or all of the eleven plastid-encoded ndh genes (A-K) form the NADH dehydrogenase-like complex (incl. a few nuclear-encoded genes), which functions in photosynthetic cyclic electron transport. In addition, loss of one copy of the large inverted repeat (IR) makes them among the smallest of plastid genomes from known obligate photosynthetic angiosperms (113-115-kb). To understand the extent of these and other rearrangements in Cactaceae, plastid genomes from representatives of each of the Cacteae, Opuntioideae, and Core Cactoideae I and II clades of cacti, together with Pereskia, a sister group to these taxa within cacti, were sequenced by Illumina methods, annotated and compared to the more distant outgroup Portulaca oleracea (Portulacaceae). Plastid genomes in cacti exhibit considerable variation in the presence and size of the IR, from the typical angiosperm IR size (~25-kb) and structure in Opuntia and Pereskia species, to one of variable size and gene content in Cactoideae II, further to multiple, convergent losses of one copy of the IR in Quiabentia, Cacteae and Cactoideae. In at least one species of the South American Echinopsis, we observe a dramatic expansion of the IR by the addition of genes normally found outside the large single copy region-IR boundary, including both matK and rbcL. Similarly, the ndh genes show similar patterns of multiple, often parallel losses throughout the Cacteae and Core Cactoideae, with the exception of the early-branching Pereskia and Opuntioideae lineages, which appear to have intact copies of most, if not all, the ndh genes. As such, plastid genomes in Cactaceae reflect the overall conservatism in genome structure across plants but also exhibit the loss of genes and rearrangements repeatedly observed in several other plant families.

1 - Arizona State University, School Of Life Sciences, PO Box 874501, Tempe, AZ, 85287, United States
2 - Arizona State University, School of Life Sciences, The College of Liberal Arts and Sciences, Arizona State University, Tempe, AZ, 85287, USA
3 - Arizona State University, Faculty of Applied Sciences and Mathematics, Mesa, Arizona, USA
4 - Florida Museum Of Natural History, 1659 Museum Rd. , Gainesville, FL, 32611, United States
5 - Sciences And Mathematics, 6073 S. Backus Mall, MC 2780, Mesa, AZ, 85212, United States
6 - University Of Arizona, Ecology And Evolutionary Biology, Tucson, AZ, 85749.0, United States

Keywords:
Cactaceae
Plastome evolution
ndh genes
Carnegiea gigantea.

Presentation Type: Colloquium Presentations
Session: CO10, Donald J. Pinkava’s legacy - the ASU Herbarium in the Sonoran Desert
Location: San Pedro 2/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 10:15 AM
Number: CO10008
Abstract ID:712
Candidate for Awards:None