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Avena ventricosa Balansa ex Coss. is considered the C-genome donor of the cultivated hexaploid oat and is a ‘priority’ species for conservation, since it has limited geographic distribution and the only recorded populations in Europe are present in Cyprus. The current study attempts to characterize the genetic structure and fragmentation of the species via the application of genotypic markers. It was revealed that the genetic variety was mainly allocated among the populations collected, since clustering obtained was according to the geographic origin of the samples and the habitat. Species distribution modeling showed that the most important climatic variable defining A. ventricosa distribution is the mean diurnal temperature. Furthermore, significant association of the genetic structure to environmental variables was detected; overall, a negative association to precipitation was confirmed, while significant correlations of genetic structure and the temperature at the time of anthesis and germination were established. The safeguarding of this valuable genetic resource is discussed. [ABSTRACT FROM AUTHOR]

Striga hermonthica, a root hemiparasitic Orobanchaceae, severely constrains grain production in sub-Saharan Africa. Host specificity and geography may play important roles in shaping the population structure of S. hermonthica, with the Rift Valley potentially presenting a significant barrier to dispersal. Genetic diversity was assessed in 12 S. hermonthica populations from locations in Ethiopia. Of these, seven populations were parasitic on sorghum, two each on tef and maize, and one on finger millet. Genetic variation was detected using four amplified fragment length polymorphism (AFLP) primer combinations. After correcting for repeatability, 385 fragments were detected across all primer combinations. The percentage of polymorphic loci was relatively high, ranging from 53.2% to 76.4%. Expected heterozygosity ranged from 0.168 to 0.279. Genetic differentiation between populations was relatively high, and all populations were significantly different from each other . FST values ranged from 0.032 to 0.293 and averaged 0.146. Genetic differences between populations could not be attributed to host specificity. Instead, geography was the main determinant of population structure. There was a correlation between geographic and genetic distance. A significant portion of the genetic variance could be apportioned on either side of the Rift Valley (5%; P = 0:001). Also, a significant geographic barrier was identified in the southern portion of the sampled region. [ABSTRACT FROM AUTHOR]

Quercus tiaoloshanica Chun et Ko, which has a narrow range of distribution, is one of the important endemic species of the tropical montane rain forest on Hainan Island, southern China. Long-term logging and habitat destruction have resulted in population decline and distribution retreat of Q. tiaoloshanica. To determine the impact of logging on the genetic diversity of Q. tiaoloshanica, the authors investigated the genetic structures using amplified fragment length polymorphism markers in four regenerated stands after logging and in one unlogged stand. Compared with the unlogged stand, the effective number of alleles per locus dropped by 1.0% in selective logging stands and by 2.0% in clear logging stands, corresponding to reductions of 3.8% and 5.2%, respectively, in mean Nei's gene diversity and 2.9% and 3.5%, respectively, in mean Shannon diversity index. No substantial genetic erosion was detected in any of the regenerated stands owing to the high tree density and high heterogeneity of the Q. tiaoloshanica stands investigated. Meanwhile, there was no natural regeneration of the species observed in a Dacrydium pierrei Hickel plantation 700 m away from the regenerated stands, suggesting the limited ability of seed dispersal of Q. tiaoloshanica. Clear logging should be undertaken cautiously because the total number of plant species dropped by 15.2% in the clear-logged stands compared with the unlogged stand. To conserve the genetic diversity of this species, as well as the plant biodiversity of tropical forests, the habitats of Q. tiaoloshanica should be protected against exploitation in terms of agricultural or other forms of land use, and some mature trees should be preserved as seed sources to maintain an adequate regeneration base for this species in the management of logging. (Managing editor: Ya-Qin HAN) [ABSTRACT FROM AUTHOR]