New evidence confirming the CD genomic constitutions of the tetraploid Avena species in the section Pachycarpa Baum.

Honghai Yan,Charlene P Wight,Changzhong Ren,Chuang Yang,Kehan Yang,Di Deng,Yuanying Peng,Zichao Ren,Pingping Zhou,Eric Jellen

doi:10.1371/journal.pone.0240703

Abstract

The tetraploid Avena species in the section Pachycarpa Baum, including A. insularis, A. maroccana, and A. murphyi, are thought to be involved in the evolution of hexaploid oats; however, their genome designations are still being debated. Repetitive DNA sequences play an important role in genome structuring and evolution, so understanding the chromosomal organization and distribution of these sequences in Avena species could provide valuable information concerning genome evolution in this genus. In this study, the chromosomal organizations and distributions of six repetitive DNA sequences (including three SSR motifs (TTC, AAC, CAG), one 5S rRNA gene fragment, and two oat A and C genome specific repeats) were investigated using non-denaturing fluorescence in situ hybridization (ND-FISH) in the three tetraploid species mentioned above and in two hexaploid oat species. Preferential distribution of the SSRs in centromeric regions was seen in the A and D genomes, whereas few signals were detected in the C genomes. Some intergenomic translocations were observed in the tetraploids; such translocations were also detected between the C and D genomes in the hexaploids. These results provide robust evidence for the presence of the D genome in all three tetraploids, strongly suggesting that the genomic constitution of these species is DC and not AC, as had been thought previously.

Highlights

IntroductionThe cultivated hexaploid oat, Avena sativa L
The cultivated hexaploid oat, Avena sativa L. (2n = 6x = 42, genomes AACCDD), is the sixth most important cereal crop cultivated worldwide [1]
Three SSR motifs ((TTC)5, (AAC)5, (CAG)5), two oligonucleotides derived from oat A and C genome specific repeats, and a wheat 5S rRNA gene fragment were used as ND-Fluorescence in situ hybridization (FISH) probes

Summary

Introduction

The cultivated hexaploid oat, Avena sativa L. (2n = 6x = 42, genomes AACCDD), is the sixth most important cereal crop cultivated worldwide [1]. The superior nutraceutical properties of the oat grain have attracted considerable attention from both breeders and consumers [2]. The genus Avena L. comprises a number of closely related species with a basic chromosome number of seven, and includes diploids, tetraploids, and hexaploids [3]. A. sativa is an allohexaploid species displaying disomic inheritance, and is closely related to the weedy species A. sterilis L. It is believed that A. sativa was domesticated from A. sterilis somewhere in Northwest Asia [4, 5].

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