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Contribution to the cytotaxonomy of Oryzopsis (Poaceae)
Author(s) -
Yazdanbakhsh Zahra,
Sheidai Masoud,
Khavarinejad RamezanAli,
Keshavarzi Maryam,
Nejadsattarei Taher
Publication year - 2010
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.2009.00562.x
Subject(s) - biology , chiasma , meiosis , pollen , ploidy , botany , genus , population , cytotaxonomy , chromosome , subspecies , karyotype , meiocyte , zoology , evolutionary biology , genetics , gene , demography , sociology
Meiotic studies were performed in twelve populations of four Oryzopsis species ( O. pubiflora , O. lateralis , O. holciformis var. longiglomis and O. barbellata ) to obtain data on the ploidy level and cytological evolution of the genus. The chromosome number 2n=2x=24 was revealed in all the species and populations studied. The present and other studies show the occurrence of two basic chromosome numbers in the genus, i.e. x=11 and x=12. Although Oryzopsis species and populations studied are diploid and are expected to form only bivalents in metaphase of meiosis‐I, quadrivalents were observed in O. pubiflora and O. lateralis , possibly due to the occurrence of heterozygote translocations. B‐chromosomes of 0–2 were observed in all species and populations studied. This is the first report of the occurrence of B‐chromosomes in the genus Oryzopsis . Several meiocytes showed the presence of double chromosome number in O. lateralis , and multipolar cells were observed in populations of O. barbellata , O. lateralis and O. holciformis var. longiglomis . The occurrence of large pollen grains (possibly unreduced) was observed along with smaller (normal) pollen grains in these species. Significant differences observed in chiasma frequency and distribution among studied species may be of use in species delimitation. The Kakan population differed significantly from the other populations of O. lateralis in meiotic characteristics. If such cytological differences are accompanied by morphological variation (under investigation), we may consider this population as a new variety or subspecies.