No abstract

A tetraploid F 2 progeny segregating for resistance to black spot, growth habit, and absence of prickles on the stem and petioles was used to construct genetic linkage maps of rose. The F 1 of the progeny, 90-69, was created by crossing a black spot-resistant amphidiploid, 86-7, with a susceptible tetraploid, 82-1134. The F 1 was open-pollinated to obtain 115 seedlings. AFLP and SSR markers were used to eliminate seedlings produced through cross-fertilization. The remaining progeny set of 52 F 2 plants was used to study the inheritance of 675 AFLPs, one isozyme, three morphological and six SSR markers. AFLP markers were developed with three combinations of restriction enzymes, EcoRI/MseI, KpnI/MseI and PstI/MseI. Most of the markers appear to be in simplex or single-dose and segregated 3:1 in the progeny. One linkage map was constructed for each parent using only the single-dose markers. The map of 86-7 consists of 171 markers assigned to 15 linkage groups and covering more than 902 cM of the genome. The map of 82-1134 consists of 167 markers assigned to 14 linkage groups and covering more than 682 cM of the genome. In the AFLP analysis, EcoRI/MseI generated nearly twice as many markers per run than PstI/MseI. Markers developed with three restriction enzyme combinations showed a mixed distribution throughout the maps. A gene controlling the prickles on the petiole was located at the end of linkage group 7 on the map of 86-7. A gene for malate dehydrogenase locus 2 was located in the middle of linkage group 4 on the map of 86-7. These first-generation maps provide initial tools for markerassisted selection and gene introgression for the improvement of modern tetraploid roses.

New microsatellites markers [simple sequence repeat (SSR)] have been isolated from rose and integrated into an existing amplified fragment-length polymorphism genetic map. This new map was used to identify quantitative trait locus (QTL) controlling date of flowering and number of petals. From a rose bud expressed sequence tag (EST) database of 2,556 unigenes and a rose genomic library, 44 EST-SSRs and 20 genomic-SSR markers were developed, respectively. These new rose SSRs were used to expand genetic maps of the rose interspecific F 1 progeny. In addition, SSRs from other Rosaceae genera were also tested in the mapping progeny. Genetic maps for the two parents of the progeny were constructed using pseudo-testcross mapping strategy. The maps consist of seven linkage groups of 105 markers covering 432 cM for the maternal map and 136 markers covering 438 cM for the paternal map. Homologous relationships among linkage groups between the maternal and paternal maps were established using SSR markers. Loci controlling flowering traits were localised on genetic maps as a major gene and QTL for the number of petals and a QTL for the blooming date. New SSR markers developed in this study will provide tools for the establishment of a consensus linkage map for roses that combine traits and markers in various rose genetic maps.

The molecular properties and roles of luteinizing hormone (Lh) and its receptor (Lhcgrbb) have not been studied for the medaka (Oryzias latipes), which is an excellent animal model for ovulation studies. Here, we characterized the medaka Lh/Lhcgrbb system, with attention to its involvement in the ovulatory process of this teleost fish. In the medaka ovary, follicle-stimulating hormone receptor mRNA was expressed in small and medium-sized follicles, while lhcgrbb mRNA was expressed in the follicle layers of all growing follicles. Experiments using HEK 293T cells expressing medaka Lhcgrbb in vitro revealed that gonadotropin from pregnant mare’s serum and medaka recombinant Lh (rLh) bound to the fish Lhcgrbb. The fish gonadotropin subunits Gtha, Fshb, and Lhb were essentially expressed at fairly constant levels in the pituitary of the fish during a 24-h spawning cycle. Using medaka rLh, we developed a follicle culture system that allowed us to follow the whole process of oocyte maturation and ovulation in vitro. This follicle culture method enabled us to determine that the Lh surge for the preovulatory follicle occurred in vivo between 19 and 15 h before ovulation. The present study also showed that oocyte maturation and ovulation were delayed several hours in vitro compared with in vivo. Treatment of large follicles with medaka rLh in vitro significantly increased the expression of Mmp15, which was previously demonstrated to be crucial for ovulation in the fish. These findings demonstrate that Lh/Lhcgrbb is critically involved in the induction of oocyte maturation and ovulation.