Sex Determination in Dioecious Silene Iatifolia (Effects of the Y Chromosome and the Parasitic Smut Fungus (Ustilago violacea) on Gene Expression during Flower Development)

Abstract

We have embarked on a molecular cloning approach to the investigation of sex determination in Silene latifolia Poiret, a dioecious plant species with morphologically distinguishable sex chromosomes. One of our key objectives was to define a range of genes that are up-regulated in male plants in response to Y chromosome sex-determination genes. Here we present the characterization of eight male-specific cDNA sequences and classify these according to their expression dynamics to provide a range of molecular markers for dioecious male flower development. Cenetically female S. latifolia plants undergo a partia1 sex reversal in response to infection by the parasitic smut fungus Ustilago violacea. This phenomenon has been exploited in these studies; male-specific cDNAs have been further categorized as inducible or noninducible in female plants by smut fungus infection. Analysis of the organ-specific expression of male-specific probes in male and female flowers has also identified a gene that is regulated in a sex-specific manner in nonreproductive floral tissues common to both male and female plants. This observation provides, to our knowledge, the first molecular marker for dominant effects of the Y chromosome in nonreproductive floral organs.Dioecy is an outbreeding mechanism in which male and female reproductive organs develop on separate individuals. This breeding strategy is used by approximately 4% of angiosperm species (Yampolski and Yampolski, 1922). However, only five families of flowering plants are known to contain dioecious species with morphologically distinguishable sex chromosomes (Parker, 1990). Silene latifolia Poiret (white campion), also known as Silene alba (Miller

The Identification of Candidate Genes for a Reverse Genetic Analysis of Development and Function in the Arabidopsis Gynoecium

“…Total RNA samples of 10 g or polyadenylated RNA samples of 4 g were analyzed on formaldehyde-containing agarose gels (Sambrook et al, 1989) and capillary blotted onto Hybond-N membranes (Amersham Biosciences, Little Chalfont, Buckinghamshire, UK) according to the manufacturer's instructions. Northern hybridizations with radiolabeled full-length cDNA probes were carried out as described by Scutt et al (1997) and washed to high stringency in solutions containing 0.1ϫ SSPE (Sambrook et al, 1989) and 0.1% (w/v) SDS at 65°C. This washing stringency has been demonstrated (data not shown) to discriminate between homologous sequences of 4 kb sharing an average of Ͼ95% nucleic acid sequence similarity.…”

Dioecy inAmborella trichopoda:evidence for genetically based sex determination and its consequences for inferences of the breeding system in early angiosperms

“…Secondly, we found a variable proportion of bisexual flowers on some predominantly male individuals in both ex situ and in situ populations. Sexual instability is a common phenomenon in dioecious plant species, and many exogenous, environmental and demographic factors are known to affect sex ratios, including plant hormones (Durand and Durand, 1991;Papadopoulou and Grumet, 2005), non-methylable nucleotide analogues (Janousek et al, 1996), temperature (Manzano et al, 2014), pathogens (Scutt et al, 1997), timing of seed set (Freeman et al, 1994) and population structure (Stehlik et al, 2008). Some of these factors strongly suggest the involvement of epigenetic mechanisms operating in sex determination, and sexual instability in A. trichopoda may therefore involve such factors, operating either at, or downstream of, sex-determining loci.…”

Male-fertility genes expressed in male flower buds of Silene latifolia include homologs of anther-specific genes

“…Seventy two clones showed no homology with the any protein within the GenBank, 18 clones were ribosomal protein, 11 clone showed similarity with expressed protein with no specific function, and 151 clone showed homology with known genes in organisms other than S. latifolia . Thirty-six clones of the sequenced 288 clones corresponded to previously identified male-specific S. latifolia genes, including men2 , men3 , men8 , men9 , men369 (Scutt et al, 1997;Scutt et al, 2002), MROS3A , MROS3B (Matsunaga et al, 1996), ST1 (Lebel-Hardenack et al, 1997), CCLS4 (Barbacar et al, 1997), SlX1 (Delichere et al, 1999), and SLP2 (Pritham et al, 2003).…”

“…By contrast, no fertile pollen was observed in any flower stalks in the infected female plants. This is probably because only the male genome contains the Y chromosome with its complete sets of anther formation and maturation genes (Scutt et al, 1997;Uchida et al, 2003).…”