Nuclear genome size and genomic distribution of ribosomal DNA in <i>Musa</i> and <i>Ensete</i> (Musaceae): taxonomic implications

Abstract

Nuclear DNA content and genomic distributions of 5S and 45S rDNA were examined in nineteen diploid accessions of the genus Musa representing its four sections Eumusa, Rhodochlamys, Callimusa and Australimusa, and in Ensete gilletii, which was the outgroup in this study. In the Eumusa (x = 11), 2C DNA content ranged from 1.130 to 1.377 pg, M. balbisiana having the lowest DNA content of all sections. M. beccarii (x = 9), a representative of Callimusa, had the highest 2C nuclear DNA content (1.561 pg). Species belonging to Rhodochlamys (x = 11) and Australimusa (x = 10) had 2C DNA contents ranging from 1.191 to 1.299 pg and from 1.435 to 1.547 pg, respectively. E. gilletii (x = 9) had 2C DNA content of 1.210 pg. The number of 5S rDNA loci in Musa varied from 4 to 8 per diploid cell. While different numbers of 5S rDNA loci were observed within Eumusa and Rhodochlamys, four 5S rDNA loci were observed in all accessions of Australimusa. M. beccarii (Callimusa) and E. gilletii contained 5S rRNA gene clusters on five and six chromosomes, respectively. The number of 45S rDNA loci was conserved within individual sections. Hierarchical cluster analysis of genome size, number of chromosomes and 45S rDNA sites suggested a close relationship between Rhodochlamys and Eumusa; Australimusa was clearly separated as were M. beccarii and E. gilletii. Within the Eumusa-Rhodochlamys group, M. balbisiana, M. schizocarpa and M. ornata formed distinct subgroups, clearly separated from the accessions of M. acuminata, M. mannii, M. laterita and M. velutina, which formed a tight subgroup. The results expand the knowledge of genome size and genomic distribution of ribosomal DNA in Musa and Ensete. They aid in clarification of the taxonomical classification of Musa and show a need to supplement the analyses on the DNA sequence level with cytogenetic studies.

Safety Assessment of Transgenic Organisms, Volume 4

“…Neumann and Hildebrand, 2009). After plantains reached humid forest climates in lowland western Africa, the crop underwent intensive diversification (De Langhe and de Maret, 1999; Karamura, 1999;De Langhe et al, 2005; Blench, 2009).…”

“…The diploid genome is rather small - Kamaté et al (2001) measured the 2C nuclear DNA content of M. balbisiana as 1.16 pg, and M. acuminata averaged 1.27 pg with a variation of 11% between subspecies, whereas triploid 2C values ranged from 1.61 to 2.23 pg (cf. Bartoš et al, 2005). These diploids therefore have some 560 to 610 million bp of DNA (Kamaté et al, 2001), of which about half has been estimated to be non-coding DNA (H ibová et al, 2007).…”

“…The diploid chromosome number together with phenotypic characteristics of the inflorescence and seeds have been the basis for conventional division of the genus into four, or sometimes five, sections (Appendices 1 & 2): section Musa (nomenclaturally correct but often traditionally still called Eumusa), Rhodochlamys, Callimusa and Australimusa, and sometimes also Ingentimusa (Simmonds, 1962;Stover and Simmonds, 1987;Simmonds and Weatherup, 1990b;Häkkinen, 2004b;De Langhe, 2009). However, researchers are finding some sections ill-defined, and that fewer sections may be more accurate (Jarret and Gawel, 1995;Shepherd, 1999;De Langhe, 2000b;Wong et al, 2002Wong et al, , 2003Nwakanma et al, 2003;Bartoš et al, 2005;cf. Häkkinen et al, 2007c;De Langhe et al, 2009).…”

“…Neumann and Hildebrand, 2009). After plantains reached humid forest climates in lowland western Africa, the crop underwent intensive diversification (De Langhe and de Maret, 1999;Karamura, 1999;De Langhe et al, 2005;Blench, 2009 (Kagy and Carreel, 2004;Kennedy, 2008). And between 1000 BC and 500 AD (during Sabean civilisation) possibly some edible Musa (ABB cooking bananas, non-plantain AABs) from India reached southwestern Arabia and nearby northeastern Africa through Arab and/or Persian traders, but there is no certain evidence (De Langhe, 2000a).…”

“…Modern techniques to detect differences have employed isozyme polymorphism (Bhat et al, 1992a(Bhat et al, , 1992b; and various DNA molecular markers, such as RAPD (Howell et al, 1994;Bhat and Jarret, 1995;Bhat et al, 1995;Damasco et al, 1996); RFLP (Gawel et al, 1992;Jarret et al, 1992;Carreel et al, 1993;Fauré et al, 1993;Bhat et al, 1994); AFLP (Ude et al, 2002a(Ude et al, , 2002bNoyer et al, 2005); and microsatellites (SSRs) (Lagoda et al, 1996;Dussart, 2001;Creste et al, 2004;Buhariwalla et al, 2005). Chloroplast DNAs of A and B cytoplasms have been differentiated (Umali and Nakamura, 2003;Boonruangrod et al, 2008), and as well their mitochondrial DNAs (Boonruangrod et al, 2008), and the genomic distribution of nuclear ribosomal DNA has been studied in various species (Bartoš et al, 2005;Boonruangrod et al, 2009). Table 1 provides a summary of some familiar or otherwise notable cultivated varieties (cultigens, landraces, cultivars) of edible Musa species and hybrids classified by cross and the level of ploidy (cf.…”