Understanding the origin and evolution of sex chromosomes requires studying recently evolved X-Y chromosome systems such as those in some flowering plants. We describe Y chromosome deletion mutants of Silene latifolia, a dioecious plant with heteromorphic sex chromosomes. The combination of results from new and previously described deletions with histological descriptions of their stamen development defects indicates the presence of two distinct Y regions containing loci with indispensable roles in male reproduction. We determined their positions relative to the two main sex determination functions (female suppressing and the other male promoting). A region proximal to the centromere on the Y p arm containing the putative stamen promoting sex determination locus includes additional early stamen developmental factors. A medial region of the Y q arm carries late pollen fertility factors. Cytological analysis of meiotic X-Y pairing in one of the male-sterile mutants indicates that the Y carries sequences or functions specifically affecting sex chromosome pairing.

• MeSH
• biologická evoluce * MeSH
• DNA rostlinná genetika   MeSH
• druhová specificita MeSH
• genetická variace MeSH
• mutace MeSH
• pohlavní chromozomy genetika   MeSH
• rekombinace genetická * MeSH
• rostlinné geny genetika   MeSH
• rozmnožování genetika   MeSH
• selekce (genetika) MeSH
• Silene genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA rostlinná MeSH

In this paper we describe a pair of novel Ty3/gypsy retrotransposons isolated from the dioecious plant Silene latifolia, consisting of a non-autonomous element Retand-1 (3.7 kb) and its autonomous partner Retand-2 (11.1 kb). These two elements have highly similar long terminal repeat (LTR) sequences but differ in the presence of the typical retroelement coding regions (gag-pol genes), most of which are missing in Retand-1. Moreover, Retand-2 contains two additional open reading frames in antisense orientation localized between the pol gene and right LTR. Retand transcripts were detected in all organs tested (leaves, flower buds and roots) which, together with the high sequence similarity of LTRs in individual elements, indicates their recent transpositional activity. The autonomous elements are similarly abundant (2,700 copies) as non-autonomous ones (2,100 copies) in S. latifolia genome. Retand elements are also present in other Silene species, mostly in subtelomeric heterochromatin regions of all chromosomes. The only exception is the subtelomere of the short arm of the Y chromosome in S. latifolia which is known to lack the terminal heterochromatin. An interesting feature of the Retand elements is the presence of a tandem repeat sequence, which is more amplified in the non-autonomous Retand-1.

• MeSH
• chromozomy rostlin genetika   MeSH
• DNA rostlinná metabolismus   MeSH
• genetická transkripce MeSH
• genom rostlinný genetika   MeSH
• koncové repetice genetika   MeSH
• molekulární sekvence - údaje MeSH
• rekombinantní proteiny genetika   MeSH
• retroelementy genetika   MeSH
• sekvence nukleotidů MeSH
• Silene genetika   MeSH
• Southernův blotting MeSH
• tandemové repetitivní sekvence genetika   MeSH
• telomery genetika   MeSH
• transkripční faktory genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA rostlinná MeSH
• mdg4 protein (gypsy) MeSH Prohlížeč
• rekombinantní proteiny MeSH
• retroelementy MeSH
• transkripční faktory MeSH

Silene latifolia is a key plant model in the study of sex determination and sex chromosome evolution. Current studies have been based on genetic mapping of the sequences linked to sex chromosomes with analysis of their characters and relative positions on the X and Y chromosomes. Until recently, very few DNA sequences have been physically mapped to the sex chromosomes of S. latifolia. We have carried out multicolor fluorescent in situ hybridization (FISH) analysis of S. latifolia chromosomes based on the presence and intensity of FISH signals on individual chromosomes. We have generated new markers by constructing and screening a sample bacterial artificial chromosome (BAC) library for appropriate FISH probes. Five newly isolated BAC clones yielded discrete signals on the chromosomes: two were specific for one autosome pair and three hybridized preferentially to the sex chromosomes. We present the FISH hybridization patterns of these five BAC inserts together with previously described repetitive sequences (X-43.1, 25S rDNA and 5S rDNA) and use them to analyze the S. latifolia karyotype. The autosomes of S. latifolia are difficult to distinguish based on their relative arm lengths. Using one BAC insert and the three repetitive sequences, we have constructed a standard FISH karyotype that can be used to distinguish all autosome pairs. We also analyze the hybridization patterns of these sequences on the sex chromosomes and discuss the utility of the karyotype mapping strategy presented to study sex chromosome evolution and Y chromosome degeneration.

• MeSH
• chromozomy rostlin genetika   MeSH
• genetické markery genetika   MeSH
• hybridizace in situ fluorescenční MeSH
• karyotypizace MeSH
• mapování chromozomů * MeSH
• pohlavní chromozomy genetika   MeSH
• repetitivní sekvence nukleových kyselin genetika   MeSH
• Silene genetika   MeSH
• Southernův blotting MeSH
• umělé bakteriální chromozomy MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• genetické markery MeSH