بررسي خصوصيات كروموزومي دو گونه مرتعي ﴿Rheum ribes و Astragalus cyclophyllos﴾

چكيده انگليسي :

Chromosome morphology in two rangeland species of Astragalus cyclophyllos and Rheum ribes Fahimeh Moazam E mail address fahimeh moazam @yahoo com April 5 2009 Department of Natural Resources Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervistor s M Bassiri E mail address bassiri em@yahoo com A F Mirlohi E mail address mirlohi@cc iut ac irAbstractAstragalus cyclophyllos is an herbaceous perennial plant of legominosae family which is verypalatable to grazing animals and bees use its nectar to make honey Rhubarb with the scientific nameof Rheum ribes is another perennial plant of Iranian rangelands belonging to the polygonaceae family Rheum ribes is a medical and edible plant of polygonacea family The stem of Rheum ribes is believedto be a good laxative and its root extract is used to cure diabetes stomach upsets vomiting smallpox and measles Its fresh petioles and stems are consumed as vegetables It is also used in making jam sweets desserts and pickles The Astragalus cyclophyllos is characterized as an vulnerable speciesdue to grazing while Rheum ribes is considered as a lower risk species Since cytogenetic studies onthese two species have not yet been conducted this study was carried out to study the chromosomecharacteristics of these two species and to prepare their Karyotype Three accessions of Astragaluscyclophyllos were collected from Semirom Fereidoonshahr and Bouinmiandasht three accessionswere collected of Rheum ribes from different regions of Isfahan and Qume proviances and cytogeneticstudies were performed The cytogenetic studies and analysis of mitotic metaphasic chromosomescontained seed germination pretreatment of tissue samples fixation of cellular and chromosomalstructures storage hydrolyzation of samples and chromosome staining Samples were observedmicroscopically for chromosome number and morphology which led to the preparation of Karyotypeand ideogram of the accessions The results of the chromosome count showed that all the Astragaluscyclophyllos accessions were tetraploid with 32 chromosomes This was in agreement with previousreport on other Astragalus species containing 32 chromosomes in a tetraploid state All the Rheumribes accessions had 42 chromosomes and their ploidy level remained unsettled Reports on thenumber of chromosome and ploidy level in other species of Rheum ribes are contradictory Accordingto the results obtained and the characteristics of Karyotype and Karyotype classifications followingStebbins method accessions 2 and 3 of the Astragalus cyclophyllos were classified as 2A class andthe Astragalus cyclophyllos accession 1 was classified as 1A class indicating more Karyotypicsymmetry The study of the Karyotypic characteristics of the 3 Rheum ribes accessions showed thataccessions 1 and 2 fell in 1A class group with more Karyotypic symmetry than the Rheum ribesaccession 3 which was in the 2A Karyotypic class with lower Karyotypic symmetry Investigation ofkaryotypic synmetry condition of accessions using Romero Zarco method confirmed the karyotypicsymmetry of accession By examining the chromosome length s variation coefficient parameters thetotal form percentage relative length of the shortest chromosome intra chromosomal asymmetryindex inter chromosomal asymmetry index and the difference of the relative length range it wasspecified that the Astragalus cyclophyllos accession 2 had more inter chromosome symmetry and thatthe Astragalus cyclophyllos accession 1 had more inter chromosome symmetry and it was specifiedRheum ribes accession 2 had more inter chromosome symmetry and Rheum ribes accession 1 hadmore inter chromosome symmetryKey wordsRheum ribes Astragalus cyclophyllos Chromosome number Karyotype Metaphase

معظم، فهيمه

بررسي خصوصيات كروموزومي دو گونه مرتعي ﴿Rheum ribes و Astragalus cyclophyllos﴾

ريواس , گون مرتعي , عدد كروموزومي , كاريوتيپ , متافاز