Identification of the High Frequency of Triploid Potato Resulting from Tetraploid × Diploid Crosses

Conventional wisdom regarding potato breeding indicates that a strong triploid block prevents the development of viable triploid seeds from crosses between tetraploid and diploid clones. However, in a recent set of crosses between elite tetraploid potatoes and an improved diploid hybrid population derived from group Stenotomum and group Phureja, 61.5% of the resulting clones were found to be triploid. If clones derived from one diploid parent suspected of producing a high frequency of unreduced gametes were excluded, then the frequency of triploid clones increased to 74.4%. Tubers of these triploids are generally intermediates of the two parental groups. Our findings indicate the possibility of using triploid potatoes in potato variety development programs and in genetic and genomic studies.

Micropropagation of Highly Productive Forms of Diploid and Triploid Aspen

The stages of getting the planting material for laying plantations of the triploid aspen (Populustremula L.) are illustrated in this work. The source material selected from the genetic fund “The gigantic aspens” is characterized. The peculiarities of using the method of clonal micropropagation when getting the planting material, the usage of a rootstock as a source of donor explants for the introduction into the culture in vitro, the influence of a kind of nutrient media and growth regulators NAA and BAP on the growth and the development of microsprouts. The distinctions in the speed of the growth of the culture in vitro of diploid and triploid clones have been analyzed. The adaptation of the plants-regenerants to the soil-conditions.

Differences in Fiber Properties and Basic Wood Density in Triploid Hybrids of Populus Tomentosa

In forest breeding programs, growth has typically been used as a selection trait of prime importance inPopulus tomentosa,whereas less attention has been given to fiber characteristics and basic wood density. Given this context, we investigated phenotypic relationships between different fiber properties, growth and basic wood density traits in nine triploid clones and one diploid clone based on a clonal trial established in 2004 in northern China. We found that fiber width showed, on average (1.4%), the lowest phenotypic variation followed by fiber length (2.2%), coarseness (5.3%). Basic wood density showed, on average (1.9%) phenotypic variation. All phenotypic correlations between fiber properties were positive (p＜0.05), ranging from moderate to strong, suggesting that selection for one trait could simultaneously affect other traits. Phenotypic correlations, on average, were quite weak but positive between growth and fiber properties and slightly negative between basic wood density and different fiber properties (p＜0.05). Individually, some of the triploid clones showed negative correlation between growth traits and fiber length. As a result, selection for fiber properties alone could reduce overall stem volume and would not directly indicate basic wood density traits and vice versa.

Determination of Holocellulose and Alpha-Cellulose Contents in Triploid Clones of Populus tomentosa Using NIRS

The aim of this work was to study the ability of NIR spectroscopy to determine holocellulose and alpha-cellulose contents in triploid clones of Populus tomentosa. For this purpose 90 trees with five families in different planting density grown in Shandong were analyzed. Calibration models were developed from wet chemical and NIR data using partial least squares (PLS) regression. High coefficients of determination (R2) and low root mean square errors of cross-validation (RMSECV) were obtained for holocellulose (R2 = 0.7805, RMSECV =0.652) and alpha-cellulose (R2 = 0.8702, RMSECV = 0.548) from wood meal. Prediction produced high correlation coefficients between laboratory and predicted values for holocellulose and alpha-cellulose contents, which R2 values are 0.7467 and 0.8505, and RMSEP are 0.993 and 0.553, respectively. This study showed that NIR analysis can be reliably used to predict holocellulose and alpha-cellulose contents in triploid clones of Populus tomentosa.

Evaluating Fertility of Triploid Clones of Hypericum androsaemum L. for Use as Non-invasive Landscape Plants

Although Hypericum androsaemum L. is a valuable landscape plant, the species can be weedy and potentially invasive in certain locations. Infertile, non-invasive cultivars of H. androsaemum with desirable ornamental features would be ecologically beneficial and valuable for the horticultural industry. The male and female fertility of 10 triploid H. androsaemum, developed with a combination of variegation and foliage colors, was investigated under greenhouse (controlled pollination) and field conditions (natural pollination). Male fertility was evaluated based on pollen viability tests (pollen staining and pollen germination). Female fertility was based on fruit set, seed set, germinative capacity of seeds, and number of seedlings produced for each flower. Although values for different measures of fertility varied among triploid clones, pollen germination was significantly reduced for all triploids and nine of the 10 triploids produced no viable seed. These results represent 100% failure of ≈171,000 potential fertilization events based on fertility levels of diploid controls. The remaining triploid clone produced two seedlings per flower compared with 260 seedlings per flower for the controls. However, the seedlings produced by the triploid clone died shortly after germination. This research documented that the triploid H. androsaemum tested are highly infertile with no measurable female fertility. These clones will provide ideal alternatives to fertile forms of H. androsaemum where invasiveness is a concern. These methods also provide a useful protocol for evaluating fertility of other taxa that are selected or developed as non-invasive cultivars of potentially weedy species.

Mode of origin and sources of genotypic diversity in triploid gynogenetic fish clones (Poeciliopsis: Poeciliidae).

Most tributaries of the Río Fuerte in northwestern Mexico contain one or more clones of allotriploid fish of the genus Poeciliopsis. We used multilocus allozyme genotypes and mitochondrial DNA (mtDNA) haplotypes to examine several potential modes of origin of these gynogenetic all-female fish. The allozyme studies corroborated earlier morphological work revealing the hybrid constitution of two triploid biotypes, Poeciliopsis 2 monacha-lucida and Poeciliopsis monacha-2 lucida. Each biotype carries one or two whole genomes from the each of the sexual species P. monacha and P. lucida. Restriction site analysis of mtDNA revealed that P. monacha was the maternal ancestor of five electrophoretically distinguishable triploid clones. Four of five clones were marked by closely related, composite, allozyme/mtDNA genotypes, suggesting they had common origins from an allodiploid clone of the P. monacha-lucida biotype. Genotypic analysis revealed that all five clones arose via the "genome addition" pathway. Fertilization of unreduced ova in P. monacha-lucida females by sperm from P. monacha and P. lucida males, respectively, gave rise to both biotypes.