Boechera microsatellite website: an online portal for species identification and determination of hybrid parentage

Abstract

Boechera (Brassicaceae) has many features to recommend it as a model genus for ecological and evolutionary research, including species richness, ecological diversity, experimental tractability and close phylogenetic proximity to Arabidopsis. However, efforts to realize the full potential of this model system have been thwarted by the frequent inability of researchers to identify their samples and place them in a broader evolutionary context. Here we present the Boechera Microsatellite Website (BMW), a portal that archives over 55 000 microsatellite allele calls from 4471 specimens (including 133 nomenclatural types). The portal includes analytical tools that utilize data from 15 microsatellite loci as a highly effective DNA barcoding system. The BMW facilitates the accurate identification of Boechera samples and the investigation of reticulate evolution among the ±83 sexual diploid taxa in the genus, thereby greatly enhancing Boechera’s potential as a model system. Database URL: http://sites.biology.duke.edu/windhamlab/

The evolution of sex is tempered by costly hybridization inBoechera(rock cress)

“…in both sexual and asexual reproduction (Böcher, 1951; Al-Shehbaz and Windham, 155 1993). Boechera is highly self-fertilizing when sexually reproducing, which enables 156 large-scale assessment of reproductive mode in interspecific hybrids via characteristic 157 levels of heterozygosity (Beck et al, 2012;Li et al, 2017). Apomixis is widespread in 158…”

Establishing the cell biology of apomictic reproduction in diploid Boechera stricta (Brassicaceae)

“…In the Brassicaceae, apomictic development is characteristic of the genus Boechera (formerly Arabis ; Al-Shehbaz, 2003 ), occurring in North America, Greenland and the Russian Far East, with the highest number of species found in the western USA ( Al-Shehbaz and Windham, 2010 ). The Boechera genus has a history of 2–5 million years and currently contains ±83 sexual diploid taxa, of which at least 64 have been involved in the hybrid genesis of hundreds of additional taxa in North America ( Kiefer et al ., 2009 ; Li et al , 2017 and references therein). Many Boechera species are diploid and predominantly inbreeding, as indicated by genetic and molecular analyses ( Schranz et al , 2005 ; Song and Mitchell-Olds, 2007 ).…”

“…Triploid Boechera display a relatively uniform mode of obligate apomictic seed formation ( Aliyu et al , 2010 ; Voigt-Zielinski et al , 2012 ). Tetraploid Boechera are rare and are characterized by both apomictic and sexual reproduction ( Li et al , 2017 ). Furthermore, male and female apomeiosis can occur together or separately, leading to the production of fertile meiotically reduced or unreduced embryo sacs and/or pollen ( Mau et al , 2013 ).…”

“…The genesis of apomixis in Boechera is highly associated with intra- and interspecific crosses ( Carman, 1997 ; Koch et al , 2003 ; Dobeš et al , 2004 a , b , 2007 ; Schranz et al , 2005 ; Beck et al ., 2012 ; Lovell et al ., 2013 , 2017 ; De Storme and Geelen, 2013 ; Mau et al , 2015 ). Of the 485 taxa included in the Boechera microsatellite database ( Li et al , 2017 ), 400 are confirmed or inferred apomictic hybrids between divergent sexual diploid taxa.…”

“…Despite rich cytogenetic data, cytoembryological analysis (mainly based on pollen microsporogenesis) is still lacking for many taxa/accessions, with scant knowledge with respect to the female reproductive pathway. The Boechera Microsatellite Website ( http://sites.biology.duke.edu/windhamlab/ ) has the most cytogenetic data, but only for 5 % of all accessions in the database (4428 specimens encompassing >95 % of all named taxa) including both published (summarized in Dobeš et al , 2006 ) and unpublished chromosome studies (according to Li et al , 2017 ). Inferring the reproductive mode from the remaining accessions requires additional observations.…”