A NEW CHROMOSOME NUMBER REPORT AND KARYOTYPE VARIATION IN THYMUS TRANSCASPICUS KLOKOV M. Moradi, V. Nazeri & M. R. Hassandokht Received 2015. 10. 20; accepted for publication 2016. 04. 27 Moradi, M., Nazeri, V. & Hassandokht, M.R. 2016. 06. 30: A new chromosome number report and karyotype variation in Thymus transcaspicus Klokov.- Iran. J. Bot. 22 (1): 59-64. Tehran. Karyotypes of five populations of Thymus transcaspicus from different geographic sites in Iran are presented. The basic chromosome number of the studied populations was obtained as x=15. Presence of 30 chromosomes in Tiwan, Hikooh, Pakotel and Golmakharan populations and 60 chromosomes in Reiin population corresponds to diploid (2n = 2x = 30) and tetraploid levels (2n = 4x = 60), respectively. Chromosome number of 2n= 30 is reported for the first time in the species. Metacentric chromosomes are the most common, but sub-metacentric chromosomes are rare. Based on intrachromosomal asymmetry (A 1 and TF %), population Reiin had the most asymmetric karyotype and population Golmakharan had the most symmetrical karyotype among the populations. According to interchromosomal asymmetry (A 2 and DRL), among diploid populations, population Pakotal had the asymmetrical karyotype. The results indicate that at least in Iran T. transcaspicus is not a uniform species in regard to its chromosome number and karyotype. Meanwhile poloidy has played a role in the evolution within species. Mehdi Moradi, Torbat-e Jam, College of Agriculture and Animal Science, Torbat-e Jam, Iran.- Vahideh Nazeri (correspondence <nazeri@ut.ac.ir>) & Mohammad Reza Hassandokht. Department of Horticultural Sciences, Faculty of Agriculture, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. Key words: Thymus; Lamiaceae; symetric karyotype; diversity; cytology; Iran ﮔﺰارش ﻳﻚ ﺟﺪﻳﺪ ﻛﺮوﻣﻮزوﻣﻲ ﻋﺪد در ﻛﺎرﻳﻮﺗﻴﭗ ﺗﻨﻮع وThymus transcaspicus Klokov. ﻣﻬﺪ ي ﻣﺮ اد ي، ﻣﺮﺑﻲ ﺟﺎم ﺗﺮﺑﺖ داﻣﭙﺮوري و ﻛﺸﺎورزي داﻧﺸﻜﺪه ﻧﺎﻇﺮي وﺣﻴﺪه ﺟﻮﻧﻘﺎﻧﻲ، داﻧﺸﻴﺎر اﻳﺮان ﻛﺮج، ﺗﻬﺮان، داﻧﺸﮕﺎه ﻛﺸﺎورزي داﻧﺸﻜﺪه ﺣﺴﻨﺪﺧﺖ، ﻣﺤﻤﺪرﺿﺎ داﻧﺸﻴﺎر اﻳﺮان ﻛﺮج، ﺗﻬﺮان، داﻧﺸﮕﺎه ﻛﺸﺎورزي داﻧﺸﻜﺪه ﻛﺎرﻳﻮﺗﻴﭗ5 ﮔﻮﻧﻪ از ﺟﻤﻌﻴﺖThymus transcaspicus ﺷﻮد ﻣﻲ اراﻳﻪ اﻳﺮان ﻣﺨﺘﻠﻒ ﻣﻨﺎﻃﻖ از. ﻛﺮوﻣﻮزوﻣﻲ ﭘﺎﻳﻪ ﻋﺪدx=15 ﻫﺎي ﺟﻤﻌﻴﺖ ﺑﺮاي آﻣﺪ ﺑﺪﺳﺖ ﻣﻄﺎﻟﻌﻪ ﻣﻮرد. وﺟﻮد30 ﺟﻤﻌﻴﺖ در ﻛﺮوﻣﻮزوم ﮔﻠﻤﺨﺎران و ﭘﺎﻛﺘﻞ ﻫﻴﻜﻮه، ﺗﻴﻮان، ﻫﺎي و60 ﺟﻤﻌﻴﺖ در ﻛﺮوﻣﻮزوم دو دﻫﻨﺪه ﻧﺸﺎن رﺋﻴﻦ دﻳﭙﻠﻮﺋﻴﺪ ﺳﻄﺢ اﺳﺖ ﮔﻮﻧﻪ در ﺗﺘﺮاﭘﻠﻮﺋﻴﺪ و. ﻛﺮوﻣﻮزوﻣﻲ ﻋﺪد2n=30 ﺷﻮد ﻣﻲ ﮔﺰارش ﮔﻮﻧﻪ در ﺑﺎر اوﻟﻴﻦ ﺑﺮاي. ﻧﻮع ﺳﺎﻧﺘﺮﻳﻚ ﻣﺘﺎ ﻫﺎي ﻛﺮوﻣﻮزوم ﺷﻮد ﻣﻲ دﻳﺪه ﺑﻨﺪرت ﻣﺘﺎﺳﺎﻧﺘﺮﻳﻚ ﺳﺎب و ﻏﺎﻟﺐ. ﻛﺮوﻣﻮزوﻣﻲ ﺗﻘﺎرن ﻋﺪم ﺷﺎﺧﺺ اﺳﺎس ﺑﺮA1 وTF و ﻛﺎرﻳﻮﺗﻴﭗ ﺗﺮﻳﻦ ﻣﺘﻘﺎرن داراي رﺋﻴﻦ ﺟﻤﻌﻴﺖ ﺑﻮد ﻛﺎرﻳﻮﺗﻴﭗ ﺗﺮﻳﻦ ﻧﺎﻣﺘﻘﺎرن داراي ﮔﻠﻤﺨﺎران ﺟﻤﻌﻴﺖ. ﻋﺪم ﺷﺎﺧﺺ اﺳﺎس ﺑﺮ ﻛﺮوﻣﻮزوﻣﻲ ﺗﻘﺎرنA2 وDRL ﭘﺎﻛﺘﻞ دﻳﭙﻠﻮﺋﻴﺪ ﻫﺎي ﺟﻤﻌﻴﺖ ﺑﻴﻦ در ﺑﻮد ﻧﺎﻣﺘﻘﺎران ﻛﺎرﻳﻮﺗﻴﭗ داراي. ﻧﻴﺴﺖ ﻳﻜﻨﻮاﺧﺖ ﮔﻮﻧﻪ ﻳﻚ ﮔﻮﻧﻪ اﻳﻦ اﻳﺮان در ﺣﺪاﻗﻞ ﻛﻪ دﻫﺪ ﻣﻲ ﻧﺸﺎن ﻧﺘﺎﻳﺞ. ﻧﻘﺶ ﮔﻮﻧﻪ ﺗﻜﺎﻣﻞ در ﭘﻠﻮﺋﻴﺪي ﻫﻤﭽﻨﻴﻦ دارد ﻣﻮﺛﺮي. INTRODUCTION Genus Thymus is one of the eight most important genera in Lamiaceae family with regard to the number of species included. Taxonomically Thymus belongs to the tribe Menteae within subfamily Nepetoideae. Available data report 215 species for the genus. Most species live on rocks or stones and well drained soils. Thymus is widely distributed in the old world. Mediterranean region has been considered as the center of diversity of the genus. Hybridization is known to be