Genetic structure and diversity of the selfing model grass Brachypodium stacei (Poaceae) in Western Mediterranean: out of the Iberian Peninsula and into the islands

Annual Mediterranean species of the genus Brachypodiurn are promising model plants for energy crops since their selfing nature and short-life cycles are an advantage in breeding programs. The false brome, B. distachyon, has already been sequenced and new genomic initiatives have triggered the de-novo genuine sequencing of its close relatives such as B. stacei, a species that was until recently mistaken for B. distachyon. However, the success of these initiatives hinges on detailed knowledge about the distribution of genetic variation within and among populations for the effective use of germplasm in la breeding program. Understanding population genetic diversity and genetic structure is also an important prerequisite for designing effective experimental populations for genomic wide studies. However, population genetic data are still limited in B. stacei. We therefore selected and amplified 10 nuclear microsatellite markers to depict patterns of population structure and genetic variation 13 among 181 individuals from 19 populations of B. stacei occurring in its predominant range, the western Mediterranean area: mainland Iberian Peninsula, continental Balearic Islands and oceanic Canary Islands. Our genetic results support the occurrence of a predominant selfing system with extremely high levels of homozygosity across the analyzed populations. Despite the low level of genetic variation found, two different genetic clusters were retrieved, one clustering all SE Iberian mainland populations and the island of Minorca and another one grouping all SE Iberian mainland populations, the Canary Islands and all Majorcan populations except one that clustered with the former group. These results, together with a high sharing of alleles (89%) suggest different colonization routes from the mainland Iberian Peninsula into the islands. A recent colonization scenario could explain the relatively low levels of genetic diversity and low number of alleles found in the Canary Islands populations while older colonization events are hypothesized to explain the high genetic diversity values found in the Majorcan populations. Our study provides widely applicable information about geographical patterns of genetic variation in B. stacei. Among others, the genetic pattern and the existence of local alleles will need to be adequately reflected in the germplasm collection of B. stacei for efficient genome wide association studies

The anatomical structure of leaf blade of the Siberian feather grasses (Poaceae: Stipa)

Results of studies of the anatomical structure of leaf blade of Siberian feather grasses are presented. A cross sections of leave blades were studied in 15 species: S. capillata, S. grandis, S. krylovii, S. baicalensis, S. praecapillata, S. consanguinea, S. orientalis, S. lessingiana, S. kirghisorum, S. dasyphylla, S. pennata, S. pulcherrima, S. zalesskii, S. glareosa, S. klemenzii. The following diagnostic characters were identified: relative height and degree of expressiveness of edges, quantity and type of veins, extent of development and arrangement of sclerenchyma as well as number and type of trichomes on the adaxial surface of leaves. Despite the uniformity of these features in many species within sections, they exhibit distinctive morphological patterns and have been proved to be taxonomically useful.В статье представлены результаты исследования анатомического строения листовой пластинки 15 видов сибирских ковылей: S. capillata, S. grandis, S. krylovii, S. baicalensis, S. praecapillata, S. consanguinea, S. orientalis, S. lessingiana, S. kirghisorum, S. dasyphylla, S. pennata, S. pulcherrima, S. zalesskii, S. glareosa, S. klemenzii. У исследованных видов были выявлены следующие диагностические признаки: относительная высота и степень выраженности ребер, их форма, количество и тип жилок, степень развития и расположение склеренхимы, количество и тип трихом на адаксиальной поверхности листьев. Несмотря на однородность этих признаков у многих видов в пределах секции, на секционном уровне они проявляют отличительные морфологические закономерности и имеют высокую таксономическую значимость

New Insight into the History of Domesticated Apple: Secondary Contribution of the European Wild Apple to the Genome of Cultivated Varieties

The apple is the most common and culturally important fruit crop of temperate areas. The elucidation of its origin and domestication history is therefore of great interest. The wild Central Asian species Malus sieversii has previously been identified as the main contributor to the genome of the cultivated apple (Malus domestica), on the basis of morphological, molecular, and historical evidence. The possible contribution of other wild species present along the Silk Route running from Asia to Western Europe remains a matter of debate, particularly with respect to the contribution of the European wild apple. We used microsatellite markers and an unprecedented large sampling of five Malus species throughout Eurasia (839 accessions from China to Spain) to show that multiple species have contributed to the genetic makeup of domesticated apples. The wild European crabapple M. sylvestris, in particular, was a major secondary contributor. Bidirectional gene flow between the domesticated apple and the European crabapple resulted in the current M. domestica being genetically more closely related to this species than to its Central Asian progenitor, M. sieversii. We found no evidence of a domestication bottleneck or clonal population structure in apples, despite the use of vegetative propagation by grafting. We show that the evolution of domesticated apples occurred over a long time period and involved more than one wild species. Our results support the view that self-incompatibility, a long lifespan, and cultural practices such as selection from open-pollinated seeds have facilitated introgression from wild relatives and the maintenance of genetic variation during domestication. This combination of processes may account for the diversification of several long-lived perennial crops, yielding domestication patterns different from those observed for annual species

Морфологическое исследование гибридогенного комплекса Poa palustris × nemoralis (Роасеае) на Среднем Урале

Исследование проявления 25 морфологических признаков в пяти среднеуральских популяциях Pоа palustris L. и P. nemoralis L. выявило высокую степень их изменчивости, как внутрипопуляционной, так и межпопуляционной и большое число особей, сочетающих признаки обоих видов. Это позволяет предполагать гибридную природу всех исследованных популяций и образование надвидовой структуры – сложного гибридогенного комплекса. Статистический анализ подтвердил отличие среднеуральских популяций P. palustris × nemoralis от западносибирских.</p

АНАТОМИЧЕСКОЕ СТРОЕНИЕ ЛИСТОВОЙ ПЛАСТИНКИ СИБИРСКИХ КОВЫЛЕЙ (POACEAE, STIPA)

В статье представлены результаты исследования анатомического строения листовой пластинки 15 видов сибирских ковылей: S. capillata, S. grandis, S. krylovii, S. baicalensis, S. praecapillata, S. consanguinea, S. orientalis, S. lessingiana, S. kirghisorum, S. dasyphylla, S. pennata, S. pulcherrima, S. zalesskii, S. glareosa, S. klemenzii. У исследованных видов были выявлены следующие диагностические признаки: относительная высота и степень выраженности ребер, их форма, количество и тип жилок, степень развития и расположение склеренхимы, количество и тип трихом на адаксиальной поверхности листьев. Несмотря на однородность этих признаков у многих видов в пределах секции, на секционном уровне они проявляют отличительные морфологические закономерности и имеют высокую таксономическую значимость