Plants regenerated from embryo cultures of an apomictic clone of Kentucky bluegrass (Poa pratensis L. ‘Baron’) are not apomictic in origin

Abstract

Plants were regenerated from tissue cultures of embryos dissected from seeds that were harvested from a selfpollinated clonal selection of Kentucky bluegrass (Poa pratensis L.) 'Baron', an apomictic cultivar. Plants were regenerated from 35 embryo-derived callus cultures of the 3280 embryos that were plated. Flow-cytometric (FCM) and RAPD-marker analyses were performed to determine if regenerants were or were not apomictic in origin. Fifteen regenerants with a 3c DNA content were classified as arising from 2n + n aberrant embryos, which was a higher frequency than expected, based on a chi-square analysis. Of the remaining 20 regenerants with a 2c DNA content, a chi-square test showed that all could have arisen from n + n sexually-derived embryos, based on the observed segregation of n + n regenerants, which fit the expected 3:1 ratio of dominant:recessive RAPD-marker phenotypes. The apparent lack of regenerants of apomictic origin, and implications for genetic transformation and breeding of Kentucky bluegrass are discussed.Abbreviations: n + 0: haploid seedling, 2n + 0: apomictically-derived seedling, n + n: sexually-derived seedling, 2n + n: aberrant seedling derived from unreduced egg and reduced sperm, FCM: Flow cytometry, RAPD: Randomly amplified polymorphic DNA, 1c: haploid, 2c: diploid, 3c: triploid

Characterization of a USDA Kentucky Bluegrass (Poa pratensis L.) Core Collection for Reproductive Mode and DNA Content by Flow Cytometry

“…Using the same criterion mentioned above, we concluded that this accession exhibited sexual embryo development (2C and 3C embryos combined with 3C and 5C endosperm) from both reduced and unreduced embryo sacs (pathways 1 and 4) as well as parthenogenic embryo development from both unreduced (2C embryo combined with 5C endosperm) and reduced (1C embryo combined with 3C endosperm) embryo sac (pathways 2 and 3). This interpretation has recently been verified by Stephens et al (2003) who observed 1C, 2C and 3C values in somatic tissue analysis in the cultivar Baron.…”

Genetic diversity ofPoa pratensisL. depending on geographical origin and compared with genetic markers

“…In grasses, RAPD and ISSR markers are most commonly used to evaluate genetic variability within and between populations, and for molecular characterization and identification of different species and their hybrids, cultivars and genotypes ( Posselt et al, 2006 ; Pivorienė et al, 2008 ; Al-Humaid, Ibrahim & Motawei, 2011 ; Motawei & Al-Ghumaiz, 2012 ; Madesis et al, 2014 ; Yuan et al, 2014 ). In P. pratensis , genetic analyses employing RAPD and ISSR focus mainly on the identification of sexual and apomictic genotypes ( Huff & Bara, 1993 ; Mazzucato et al, 1995 ; Barcaccia et al, 1997 ; Barcaccia, Veronesi & Falcinelli, 1998 ; Stephens et al, 2006 ); the assessment of genetic variability and identification of genotypes and cultivars ( Lickfeldt, Voigt & Hamblin, 2002 ; Ning et al, 2005 ; Liang et al, 2009 ; Fard et al, 2012 ; Wang et al, 2012 ; Yuan et al, 2015 ); determining the genetic relationships between different genotypes and species belonging to the genus Poa and their hybrids ( Johnson et al, 2002 ; Curley & Jung, 2004 ; Patterson, Larson & Johnson, 2005 ; Goldman, 2008 ; Goldman, 2013 ); and identification of pathogens responsible for fungal diseases in grasses ( Hsiang et al, 2000 ). Both marker systems can generate high resolution band patterns and high levels of polymorphism as high as 90%.…”

Characterization of morphological traits and RAPD polymorphism in selected forms of Kentucky bluegrass (Poa pratensis L.)

“…Kuntze, Agrostis stolonifera L., Agrostis spp., Poa annua, Poa compressa and Poa pratensis (Caetano-Anollés 1998;Al-Humaid & Motawei 2004;Ning et al 2005;Fard et al 2012). RAPD analyses of Poa pratensis, primarily, focused on: identification of sexual and apomictic genotypes (Huff & Bara 1993;Mazzucato et al 1995;Barcaccia et al 1997Barcaccia et al , 1998Stephens et al 2006), assessment of genetic diversity, identification of different genotypes and cultivars (Lickfeldt et al 2002;Al-Humaid & Motawei 2004;Ning et al 2005;Liang et al 2009;Fard et al 2012;Wang et al 2012), attempts to determine the genetic relationships between different genotypes and species belonging to the genus Poa (Johnson et al 2002;Curley & Jung 2004;Patterson et al 2005), and identification of pathogens responsible for fungal diseases in grasses (Hsiang et al 2000). As evidenced by the results of research presented in the literature (Johnson et al 2002;Ning et al 2005;Rajasekar et al 2005;Szenejko et al 2009;Szenejko 2013) various forms of Poa pratensis are characterized by a high level of band polymorphism, estimated to be over 80%.…”