Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Naeger, James [1], Golenberg , Edward M [2].

Mode and Tempo of Sequence and Floral Evolution within the Anserineae.

The Chenopodiaceae Tribe Anserineae Dumort was recently proposed to include the genus Spinacia and the genus Blitum which include the previously named Chenopodium bonus-henricus, Chenopodium foliosum, Chenopodium capitatum, Chenopodium hastatum, Monolepis nuttalliana, and Scleroblitum atriplicinum (Fuentes-Bazan, Uotila, and Borsch, 2012). In addition to domestication that occurred within the Spinacia within the last 1500-2000 years, the tribe demonstrates extensive evolution within its floral development. This evolution includes variation in the reduction in numbers of the floral organs, and the development of dioecy, protogeny, and gynomonoecy among the members in this tribe. In this study we analyzed the sequence evolution of seven genes in a sample of the Tribe Anserineae that included Spinacia oleracea, Spinacia turkestanica, Spinacia tetrandra, Blitum (Chenopodium) bonus-henricus, Blitum(Chenopodium) foliosum (= Blitum virgatum), and Blitum (Monolepis) nuttalliana. Two genes, rbcL and matK, are chloroplast genes that have been used extensively in phylogenetic studies. The nuclearly transcribed rbcS encodes a protein that interacts with the small subunit in the Rubisco complex and functions within the chloroplast. The remaining four genes are nuclear and are involved in floral development, the C class floral organ identity gene AGAMOUS, the two B class floral organ identity genes APETALA3 and PISTILATA, and the F-box gene UFO. The two B class floral identity genes affect the development of the fourth whorl in Spinacia as well as maintaining the stamen identity function and thus are required to generate stamenate flowers (Sather, Jovanovic, and Golenberg, 2010). UFO interacts with the SCF complex (Wang et al., 2003) and may be involved in the gibberellic acid regulation of the B class floral organ identity genes. In comparison, AGAMOUS is expressed in both stamenate and pistilate flowers (Sather et al., 2005), and therefore is not expected to be a factor in the morphological evolution within this tribe. Our results indicate variation in rates of nucleotide substitutions among the species with Spinacia species showing generally faster rates of substitutions. Insertion-deletion events in both exons and introns are also extensive across all taxa and suggest regulatory or protein structure effects that may be phenotypically significant. Gene specific patterns of deletions also indicate potential preadaptive conditions evolving within the Tribe that have been linked to floral evolution. Gene duplications also occur within floral homeotic genes, but do not appear to persist within the tribe, suggesting an early loss of function.

1 - Wayne State University, Department of Biological Sciences, Detroit , MI, 48202, USA
2 - Department Of Biological Sciences, Wayne State University, Department Of Biological Sciences, Wayne State University, Detroit, MI, 48202, USA

Keywords:
Anserineae
floral development
evolution of male and female phenotypes
gene sequence evolution.

Presentation Type: Oral Paper:Papers for Topics
Session: 41
Location: Payette/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 2:45 PM
Number: 41006
Abstract ID:335
Candidate for Awards:None