Detection of segregation distortion loci in triticale (x Triticosecale Wittmack) based on a high-density DArT marker consensus genetic linkage map

<p>Abstract</p> <p>Background</p> <p>Triticale is adapted to a wide range of abiotic stress conditions, is an important high-quality feed stock and produces similar grain yield but more biomass compared to other crops. Modern genomic approaches aimed at enhancing breeding progress in cereals require high-quality genetic linkage maps. Consensus maps are genetic maps that are created by a joint analysis of the data from several segregating populations and different approaches are available for their construction. The phenomenon that alleles at a locus deviate from the Mendelian expectation has been defined as segregation distortion. The study of segregation distortion is of particular interest in doubled haploid (DH) populations due to the selection pressure exerted on the plants during the process of their establishment.</p> <p>Results</p> <p>The final consensus map, constructed out of six segregating populations derived from nine parental lines, incorporated 2555 DArT markers mapped to 2602 loci (1929 unique). The map spanned 2309.9 cM with an average number of 123.9 loci per chromosome and an average marker density of one unique locus every 1.2 cM. The R genome showed the highest marker coverage followed by the B genome and the A genome. In general, locus order was well maintained between the consensus linkage map and the component maps. However, we observed several groups of loci for which the colinearity was slightly uneven. Among the 2602 loci mapped on the consensus map, 886 showed distorted segregation in at least one of the individual mapping populations. In several DH populations derived by androgenesis, we found chromosomes (2B, 3B, 1R, 2R, 4R and 7R) containing regions where markers exhibited a distorted segregation pattern. In addition, we observed evidence for segregation distortion between pairs of loci caused either by a predominance of parental or recombinant genotypes.</p> <p>Conclusions</p> <p>We have constructed a reliable, high-density DArT marker consensus genetic linkage map as a basis for genomic approaches in triticale research and breeding, for example for multiple-line cross QTL mapping experiments. The results of our study exemplify the tremendous impact of different DH production techniques on allele frequencies and segregation distortion covering whole chromosomes.</p

Инфекции нижних дыхательных путей респираторно-синцитиальной вирусной этиологии у недоношенных детей и детей с бронхолегочной дисплазией

The article is devoted to the study of features of lower respiratory tract infection associated with respiratory syncytial virus. 40 cases of RSV-bronchiolitis in preterm children under year with/without bronchopulmonary dysplasia were analyzed. It was established that disease in those groups of patients had severe course because of the respiratory failure, which dominates in clinical pictures as symptoms of bronchial obstruction and apnea. Treatment of severe RSV-infection often demand admission to intensive care unit, supplemental oxygen and/or mechanical ventilation.Статья посвящена изучению особенностей поражения нижних дыхательных путей при респираторно-синцитиальной вирусной (РСВ) инфекции. Проанализировано 40 случаев РСВ-бронхиолита у недоношенных детей первого года жизни с бронхолегочной дисплазией и без нее. Установлено, что заболевание у данного контингента пациентов имеет тяжелое течение за счет развития дыхательной недостаточности, которая является основным клиническим проявлением, наряду с симптомами бронхиальной обструкции и апноэ. Лечение тяжелой РСВ-инфекции зачастую проводится в условиях отделения реанимации и интенсивной терапии, необходимо проведение оксигенотерапии и искусственной вентиляции легких

Association analysis of low-phosphorus tolerance in West African pearl millet using DArT markers

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a food security crop in the harshest agricultural regions of the world. While low soil phosphorus (P) availability is a big constraint on its production, especially in West Africa (WA), information on genomic regions responsible for low-P tolerance in pearl millet is generally lacking. We present the first report on genetic polymorphisms underlying several plant P-related parameters, flowering time (FLO) and grain yield (GY) under P-limiting conditions based on 285 diversity array technology markers and 151 West African pearl millet inbred lines phenotyped in six environments in WA under both high-P and low-P conditions. Nine markers were significantly associated with P-related traits, nine markers were associated with FLO, whereas 13 markers were associated with GY each explaining between 5.5 and 15.9 % of the observed variation. Both constitutive and adaptive associations were observed for FLO and GY, with markers PgPb11603 and PgPb12954 being associated with the most stable effects on FLO and GY, respectively, across locations. There were a few shared polymorphisms between traits, especially P-efficiency-related traits and GY, implying possible colocation of genomic regions responsible for these traits. Our findings help bridge the gap between quantitative and molecular methods of studying complex traits like low-P tolerance in WA. However, validation of these markers is necessary to determine their potential applicability in marker-assisted selection programs targeting low-P environments, which are especially important in WA where resource-poor farmers are expected to be the hardest hit by the approaching global P crisis

Regulation of regeneration growth conditions in small clear cuts - the effect of gap parameters on biotic factors influence

Optimisation of patch selective cutting, especially the interaction between size and shape of artificial gaps and biotic factors influencing tree regeneration, is rather sparsely documented in Polish silvicultural textbooks. The removal of trees can increase availability of nutrients in artificial gaps. Establishment of root gaps and vigorous development of vegetative cover (weeds) is another consequence. This paper presents review of investigations that describe interactions between mentioned factors influencing regeneration growth and parameters of gaps. The special attention is paid to potential application of cited results in practical silviculture