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Pollen viability and male meiosis in intraspecific hybrids of Hydrangea aspera subsp. aspera Kawakami group (2n = 2x = 36) and subsp. sargentiana (2n = 2x = 34) were investigated. Although it had been assumed that they were sterile, pollen viability was observed; it varied from 2.5% to 12.1%. The production of gametes with different chromosome numbers was implied by the analysis of the dispersion of the diameter distribution of pollen grains. Analysis of male meiosis made it possible to identify the origins with two major categories of meiotic aberrations: abnormal chromosome distribution (early chromosome migration at metaphase, lagging chromosomes at anaphase, micronuclei at telophase), leading to the formation of unbalanced tetrads and/or ones with supernumerary microspores; and abnormal spindle orientation in metaphase II (tripolar, fused and parallel spindles), leading to the formation of dyads or triads. The mode of 2n pollen formation is of the First Division Restitution type. The high level of parental heterozygosity that is normally associated with them should facilitate the transfer of a polygenic trait in breeding programme. [ABSTRACT FROM AUTHOR]

The effect of genotype factors, year and their interaction was assessed on six architectural variables of eight cultivars of rose bush. Plants were grown in pots in a greenhouse in the spring of 2011 and 2012, two highly contrasted years in terms of the quantity of cumulative radiation, with a relative deviation (for 2012 compared to 2011) ranging from −24.6% (April) to +13.7% (March). Their architecture was digitized at two observation scales, the plant and the axis. Highly significant genotype ( G) and year ( Y) effects were revealed for all of the variables measured, as well as a G × Y interaction. Concerning the year effect, it was significantly higher in 2012 and for all of the variables measured. The G × Y interaction was due to (i) different genotype groupings according to year, (ii) difference response amplitudes between years according to genotype. Broad-sense heritability was calculated for each of these variables. It was moderate to high, ranging from 48% for the length of long axes to 98% for the number of metamers on long axes. [ABSTRACT FROM AUTHOR]

A total of 85 Chinese Cymbidiums and one Zygopetalum were collected and analysed using 29 simple sequence repeats ( SSRs) and 12 intersimple sequence repeats ( ISSRs). These Chinese Cymbidiums are some of the most popular cultivars in market. The pairwise genetic distance between these accessions averaged 0.897, ranging from 0.259 to 1.000. A model-based clustering analysis revealed five genetic groups with serious admixture ancestry, as indicated by a fixation index of 0.156 and only 10.67% genetic variation among groups. By analysing the cross-compatibility and pollen morphology, Chinese Cymbidiums are revealed to have high compatibility for intra- and interspecific crosses. Notably, Zygopetalum mackayi had high compatibility with Chinese Cymbidiums and shared similar morphologies in terms of pollinia and pollen grain. This study is the first to report a successful cross between Zygopetalum and Chinese Cymbidiums. The high compatibility offers the potential for introducing Zygopetalum mackayi's superior traits into Chinese Cymbidiums. The similar pollen morphology as well as the low genetic differentiation might be related to the high cross-compatibility among these accessions. [ABSTRACT FROM AUTHOR]

Eustoma grandiflorum is one of the leading cut-flowers in Japan. There are market demands for cultivars with deep-yellow flowers, but they have never been bred successfully. By investigating the carotenoid accumulation and carotenogenic gene expressions, this study attempted to explore the reasons that block the formation of deep-yellow colour in Eustoma. High performance liquid chromatography analysis showed that the carotenoid compositions in petals were similar to those in leaves, accumulating mainly lutein, violaxanthin and β-carotene. The total carotenoid contents decreased as the petals matured in all the cultivars tested. Quantitative real-time PCR analysis showed that the expression levels of PSY, LCYB, ZDS and LCYE showed significant differences between white and pale-yellow petals or between petals and leaves, indicating that these enzymes may play a key role in the carotenoid biosynthesis in E. grandiflorum. The expression levels of CCD4 were high in both pale-yellow and white petals during development, suggesting that carotenoid degradation activity is high in the petals. We then conclude that the total carotenoid accumulation level could be determined by the balance between carotenoid biosynthesis and degradation activities. [ABSTRACT FROM AUTHOR]

Black spot of rose is distributed throughout the world and is the most serious disease of roses ( Rosa spp.) in the outdoor landscape. Resistance breeding has been frustrated by the occurrence of races of the causal pathogen Diplocarpon rosae. Races from Germany, North America and the UK have been characterized and maintained in a pathogenic state. However, these races were characterized using independent sets of host genotypes and are referenced using different nomenclatures. In the present study, a total of 15 D. rosae isolates from these locations, as well as Belgium and Italy, were inoculated to a common set of 15 rose cultivars in replicated, detached leaf trials. Baby LoveTM (cv. Scrivluv) was resistant to all isolates except for one originating from the UK. The rose cultivars Mrs Doreen Pike (Ausdor) and Hansa were resistant to all isolates except for one originating from Minnesota, USA. No rose genotype was universally susceptible. A total of 11 pathogenic races were differentiated based on their unique host ranges and were assigned an international race nomenclature. Nine cultivars are proposed as the first standard set of differential genotypes for characterization of D. rosae races. [ABSTRACT FROM AUTHOR]