Session VI – Plant Breeding, Germplasm Utilization and Cereal Genomics – Poster VI-23a*

Cytogenetic and Morphological Diversity of the Genus Avena L. in Iran

Masoud Sheidai

Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran

Email: msheidai@yahoo.com

ABSTRACT

Phenetic analyses were performed on morphological characters of sixty-one populations of 7 Avena species growing in Iran, namely A. eriantha Dur. A. clauda Dur., A. barbata Pott ex Link., A. wiestii Steud., A. fatua L., A. sterilis ssp. ludoviciana L. and A. sativa L.

In total 45 quantitative and qualitative morphological characters were studied. Characters were selected based on those reported by Baum and our own field studies. Intraspecific variations as well as inter-specific relationships were investigated using cluster analysis and ordination method based on principal components analysis. The results obtained are: 1- intraspecific morphological variations observed in Avena species are due to quantitative characters, 2- phenetic analyses of morphological characters grouped diploid,

tetraploid and hexaploid species in distinct clusters/ groups supporting Baums, classification, 3- morphological characters distinguishing Avena species studied are presented, and 4- new chromosome number is reported for some of the species. Cytogenetic analysis revealed the presence of 2n = 14, 28 and 42 chromosome number in the species studied, some of which are new reports. A single population of A. eriantha showed the presence ofplants possessing 2n = 2x = 14 as well as 2n = 4x = 28 chromosome number. Detailed cytogenetic studies showed the occurrence of cytomixis and unreduced (2n) gamete formation the reason for polyploidy formation in this species. A single B-chromosome was observed in A. eriantha. Populations of A. barbata and A. wiestii possessed 2n = 4x = 28, while populations of A. sterilis ssp. ludoviciana possessed 2n = 6x = 42 chromosome number. Tetraploid and hexaploid species showed diplontic behavior and formed only bivalents possibly due to their allopolyploid nature. Cytomixis and chromosome elimination led to aneuploid and unreduced pollen mother cell formation in the species studied. χ2 test performed on the mean values of total meiotic data among the studied species/ populations with similar chromosome numbers as well as the relative meiotic values among the species with different chromosome numbers did not show a significant difference. Therefore it seems that although a change in chromosome number (ploidy level) has played a role in Avena species diversification, no major (significant) change has occurred in the number of genes controlling chiasma formation and chromosomal association. Elimination of the micronuclei was noticed in a large number of telophase-I, and II cells as well as microspores released at the end of telophase-II of A. eriantha and A. wiestii in a different way from cytomixis.