Ribosomal DNA (rDNA) repeat unit length polymorphism was examined in 285 accessions of wild barley, Hordeum spontaneum C. Koch, which were collected from 27 locations across Jordan. As many as 19 spacer length variants (slvs) or rDNA alleles were available, which formed 70 slv phenotypes. The two missing alleles (098, 099) of the series (097, 100-118) and one additional allele 119 were also discovered in the present study thus raising the number of ribosomal slvs in barley to 24. Relatively more frequent rDNA alleles were analyzed in detail, and it was shown that they occurred non-randomly at locations with different environmental factors (annual rainfall, highest and lowest temperatures, altitude, longitude, latitude) and exhibited association with specific environments. Ecogeographical factors, rather than geographical factors per se, seem to affect the distribution of rDNA alleles. The present study thus demonstrates that rDNA repeat unit length polymorphism in some cases can be adaptive in nature.
Bibliographical noteFunding Information:
Thanks are due to the Council of Scientific and Industrial Research (CSIR), New Delhi, India for financial assistance to PKG and to the Israel Disount Chair of Evolutionary Biology and the Ancell-Teicher Research Foundation for Genetics and Molecular Evolution for financial assistance to EN.
- Hordeum spontaneum
- Intergenic spacer
- Spacer length variant (slv)
ASJC Scopus subject areas
- Agronomy and Crop Science
- Plant Science