The present report is based on a cytological data base on 614 (56.0 %) of the total 1104 recognized species and 82 (90.0 %) of the 88 recognized genera of gymnosperms. Family Cycadaceae and many genera of Zamiaceae show intrageneric uniformity of somatic numbers, the genus Zamia is represented by a range of number from 2n=16-28. Ginkgo, Welwitschia and Gentum show 2n=24, 2n=42, and 2n=44 respectively. Ephedra shows a range of polyploidy from 2x-8x based on n=7. The family Pinaceae as a whole shows 2n=24except for Pseudolarix and Pseudotsuga with 2n=44 and 2n=26 respectively. Araucariaceae constantly shows 2n=26 while Podocarpaceae has a range of 2n=18-38. Sciadopityaceae and Cupressaceae are represented by 2n=20 and 2n=22 respectively. Taxaceae shows variable numbers of 2n=24, 36 and 22. Polyploidy is exceptional being represented by 8.0 % of the taxa studied. B-chromosomes have been studied in 31 taxa while heteromorphic sex chromosomes have been reported in some dioecious taxa.
Nuclear Expressed Sequence Tag (EST) microsatellite markers were developed for the Tasmanian palaeoendemic conifer Lagarostrobos franklinii (Hook.-f.) Quinn for genetic studies. RNAseq data was mined for EST microsatellites, and primer pairs were synthesised from 70 contigs with 50 producing amplification products. Of these 50, 10 reliably amplified and displayed polymorphism across 8 samples representing the entire species range. The genetic diversity of these 10 loci was then examined in three wild populations (84 samples). The number of alleles varied from two to thirteen per locus with the average number of alleles per population ranging between 3.0 – 4.7. Observed and expected heterozygosity ranged from 0.34 – 0.42 and 0.37 – 0.44, respectively. Marker cross-amplification was tested in the New Zealand sister species Manoao colensoi (Hook. f.) Molloy, but no markers amplified reliably, which possibly reflects the age of divergence between these species (~64 million years). These are the first microsatellite markers developed for the monotypic genus Lagarostrobos. They will be valuable for assessing the species extant genetic diversity, the impact of past climatic perturbations and human disturbance and the role of clonal propagation in recruitment.
Genetic variability in date palm genotypes collected from different regions of southern Tunisia was analyzed using a Start Codon Targeted (SCoT) marker system. Thirty-one accessions collected from three locations were investigated. One hundred and nine amplicons were produced among which 84 % were polymorphic. The PIC value and the Rp values testified of the efficiency of used primers. The percentage of polymorphic loci (Pp) varied from 44.57 to 83.70 %, Nei‘s gene diversity (H) from 0.175 to 0.273 with a mean of 0.228, and Shannon‘s information index (I) values ranging from 0.257 to 0.409 with an average value of 0.338 were illustrated. The Tunisian date palm populations exhibited high genetic differentiation (GST = 0.319) and gene flow (Nm = 1.063). The AMOVA analysis presented 70 % of the variation within the population and 30 % of the variation between them. Phylogenetic analysis and the Bayesian clustering approach also revealed high genetic variation among genetic variants with a net divergence of the wild insular population of Kerkennah from other cultivars. The present investigation suggests the effectiveness of the SCoT marker system to estimate the genetic diversity of Phoenix dactylifera genotypes.
Forest companies prefer a coppice system as a silvicultural strategy owing to its economic and sustainability advantages compared to developing new plantations for second rotations. However, studies aiming to determine the selection of superior genetic material for this management strategy are scarce. In this study, we evaluated five clonal tests of Eucalyptus spp. located in Itatinga and Angatuba, São Paulo State, Brazil, to determine the genetic correlations and control of productivity for regrowth management in two rotations. The volume (m3) and survival of the Eucalyptus spp. clonal tests were determined for the two rotations at 5.5 years of age. The experiments were carried out in a randomized block design with six replicates, five plants per plot, and unbalanced treatments. The heritability in the normal scale () for the survival ranged from 0.056 to 0.11, the heritability in the broad sense () ranged from 0.205 to 0.334, and the genotypic correlation was positive and high (0.71-0.86), and statistically significant to the genetic means for the two rotations. The ranking of the best clones in the second rotation was similar (76 %) to their ranking in the first selection. Thus, for the evaluated material, there was no need for the second measurement to obtain accurate selection when managing a coppice system.
Genetic variation is a major component of plant development and adaptation, and recent studies have shown that genetic variation among plant species can have important ecological effects. Oriental beech (Fagus orientalis Lipsky) is a dominant tree species in the Hyrcanian forests, where it occupies approximately 18 % of the forested area. In this study, nine expressed sequence tag simple sequence repeat (EST-SSR) markers were used to determine the genetic diversity and structure of Iranian Oriental beech populations growing at different altitudes. We further compared the genetic structures of the Iranian populations to a F. orientalis and a Fagus sylvatica L. population from the hybrid zone of the two taxa in southeast Europe, and to a F. sylvatica population from central Europe. All populations showed a high genetic diversity, which was similar to other F. orientalis and F. sylvatica populations from Europe. The genetic differentiation among Iranian beech populations was very low. In contrast, distinct genetic differentiation was found between the Iranian populations and the analyzed European populations (F. orientalis and F. sylvatica). One EST-SSR was identified to differentiate (GST: 0.503) between F. orientalis and F. sylvatica with very pronounced allele frequency differences between taxa. Specifically, the Fagus sylvatica characteristic allele 189 was almost absent from all Iranian populations and present in low frequencies in F. orientalis populations from other regions. This study helps to extend the knowledge of genetic diversity and genetic structure of Iranian Oriental beech populations. It further gives insights into the genetic differentiation between F. orientalis populations from the center and the edge of the species’ distribution range as well as between Oriental and European beech.
Research on the state and dynamics of the gene pool (an important natural resource that determines the potential fitness of living organisms and, ultimately, their long-term survival) becomes an important problem in the context of increased anthropogenic environmental impact. They are especially important for key species of ecosystems of a global scale importance. Larix sibirica Ledeb., which spreads from the Western Siberia to the Russian North-West, is one of such forest tree species. We identified patterns of genetic structure of populations on the example of the species’ Western race on the Middle and Northern Urals. The analysis of nucleotide polymorphism of genes of ABA-inducible protein, MADS-box-transcription factor and of 4-kumarat: CoA ligase (a part of the gene) was used as a method. Evidences were obtained that a part of the populations previously formed a single large population. At the same time, populations with different gene pools were found. As a result, differences between populations within the region were more pronounced (fixation index FST = -0.021 – 0.260, total haplotype diversity Hd = 0.636 – 0.911; nucleotide diversity π = 0.005 – 0.009; number of mutations θW = 0.005 – 0.012) than in other parts of the race. Causes of this phenomenon are discussed. It was concluded that the larch forests with a unique gene pool and/or high genetic diversity should be objects of population-oriented forestry and conservation.
The influence of sexual dimorphism on commercial-biological traits of the most widespread poplar of the world Populus tremula L. in the Central forest-steppe of the European territory of Russia was studied. The analysis was made of the distribution of male and female clones in general, the effects of humidity, the richness of the soil, and surrounding vegetation on their productive capacity as well as core rot damage. The study presents survey results of 620 aspen plots spread out over an area of 823 hectares as well as more detailed data obtained from 3 pairs of test plots in which the indicators of male and female aspen stands were compared under identical or similar conditions. The study showed that the area of male aspen in the studied region is 4.5 times larger than that of females. The former prevail in drier and less fertile conditions while females gravitate towards more favorable growing conditions. The comparison of the productive capacity of male and female clones of the same age class, growing in identical or similar growing conditions showed that the height, diameter, and volume of the trunks were higher in male trees. Female aspen trees were less affected by core rot in the best conditions of growth, and male ones were more resistant at the worse ones.
Marker-assisted selection (MAS) is implemented to improve Camellia oleifera yield and fruit attributes for meeting China’s increased demand for new varieties development. We conducted three-generational (G0, G1, and G2) hybridization (diallel mating) and selection experiment and used Sequence-Related Amplified Polymorphism (SRAP). SRAP markers to investigate their utility in a MAS framework. The utilized SRAP markers were instrumental in hybrid authenticity and the identification of matroclinal or patroclinal inheritance presence, thus guiding mating pair selection and direction (their role as male or females). Across the studied 3 generations, estimates of genetic diversity parameters showed steady increase with percentage increase of ((G0 to G1 and G1 to G2) 9.25 and 9.05: observed number of alleles; 3.12 and 7.80: means effective number of alleles; 12.35 and 22.34: Nei‘s gene diversity; and 14.21 and 21.77: Shannon‘s index), indicating lack of diversity reduction associated with selection. Estimates of genetic distance and their correlation with heterosis were useful in guiding selection of mating pairs for achieving the desired yield and fruit attributes (fruit diameter, height, weight, and index, peel thickness, number of seeds per fruit, seed weight per fruit, and seed rate). Most yield and fruit attributes exhibited high broad-sense heritability with increasing trend over generation intervals, indicating the increased potential of hybrid breeding for this species.
The Gran Chaco is the largest dry forest in South America. One of the key taxa of this biome is the genus Prosopis (Fabaceae) which contains several economically important species. One of the characteristics of this genus is its natural capacity to exchange genetic information among congeneric species, generating zones of high morphological and genetic variability at contact points. The study and management of these contact areas can contribute to the dynamic conservation of these native genetic resources. In this study, we analysed three sites within a gradient of land aridity, where P. nigra and P. alba grow in sympatry and apparently hybridize. This is the first study performed in both, Prosopis pure sites and hybrid swarm, which includes a spatially explicit approach and simultaneously analyses fruit and leaf morphological variation, together with molecular information (microsatellites markers). We performed a multivariate morphological analysis, Bayesian genetic clustering and multivariate associations between genetic and morphological variability in the pure parental populations and in the hybrid swarm, considering possible spatial autocorrelation. Bayesian cluster analysis revealed two distinct groups corresponding to each species, differentiating the pure morphotypes from sites 1 and 2. Site 3, corresponding to the hybrid swarm, was composed of pure P. alba and P. nigra trees and hybrid individuals. We found morphological and molecular evidence of hybridization between P. alba and P. nigra, and detected novel phenotypes in the hybrid site.
To promote solid wood production, the diameter at breast height, height, stress-wave velocity, surface-released strain, basic density and compressive strength parallel to the grain were measured for 10 half-sib families of 12-year-old Eucalyptus camaldulensis Dehnh. trees growing in Thailand. Based on the results, growth rates, correlations among measured properties, radial and among-family variations of wood properties, and their repeatability were evaluated. Diameter at breast height, height, and wood volume were exponentially increased at initial stage, and then gradually increased toward to 12 years after planting. The maximum current annual increment and mean annual increment in wood volume showed at age of 8 and 11years old, suggesting that rotation period for optimum productivity may be ranged from 8 to 11 years old. Wood with stable properties was found greater than 6 cm from the pith. These results indicate that 12-year-old E. camaldulensis trees had already reached the maturation stage. No significant correlations were found between growth characteristics and wood properties. Significant variances in the height, stress-wave velocity, and basic density were found among the 10 families. The F-values and repeatability of the wood properties in the outer wood were higher than those in the inner wood. These results indicate that the properties of the outer wood are closely related to genetic factors. Thus, to obtain superior E. camaldulensis trees for solid wood production, the family selection should be conducted using the outer wood of aged trees.