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  • Author: S. Q. Li x
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Microsatellite-based Genotyping of the Commercial Eucalyptus Clones Cultivated in China

Abstract

A proper identification of clones is necessary in clonal forestry and will help to protect the legitimate interests of breeders, growers and industry. Twenty-four of the Eucalyptus clones most widely cultivated in China were analyzed using a set of 24 microsatellite markers to develop their DNA-based fingerprints and exploit the genetic variations. A total of 286 alleles were detected, averaging at 11.9 alleles per marker locus. All the microsatellites were polymorphic among the clones investigated. The observed heterozygosity (Ho) varied with locus between 0.500 and 1.000 with a mean of 0.885. The 24 clones could be uniquely fingerprinted based on their multilocus genotypes at a minimum of three loci (Embra169, Embra72 and Embra2). The dendrogram constructed from the genotypic similarity coefficients separated the 24 clones into three groups, matching essentially the historically known or speculated clonal origins. Clones T13, Guanglin-5 and Guanglin-9 turned out to be full siblings of cross DH32 while the DH201-2 sampled here appeared to be mislabelled.

Open access
Hybridizing ability and heterosis between Eucalyptus urophylla and E. tereticornis for growth and wood density over two environments

Abstract

Interspecific hybrids of Eucalyptus urophylla × E. tereticornis in a factorial-mating design were used to analyze general hybridizing ability (GHA), specific hybridizing ability (SHA) and heterosis for height (H; 0.5, 1.5, 2.5, 4 and 7.5 years in age), diameter at breast height (D; ages 1.5, 2.5, 4 and 7.5) and wood density (WD; age 7.5) across two environments. The GHA variances were significant for all traits, and those of the SHA were also significant for most of the traits but with less magnitude, indicating the greater importance of additive gene effects in explaining the phenotypic variation among hybrids. The narrow-sense heritability (h2) and dominance (d2) estimates with hybrid growth and wood density ranged between 0.02±0.05 (d2 in D7.5) and 0.23±0.10 (d2 in H1.5) over the different ages, suggesting weak additive and dominant effects on these traits. Additive genetic correlations of growth with wood density were weak at age 7.5. Female general combining ability (GCA) based on maternal open-pollinated families was not necessarily a good indicator of GHA as their correlations were 0.48 (P=0.17), 0.65 (P=0.04) and -0.56 (P=0.10) for H7.5, D7.5 and WD7.5, respectively. A great proportion of hybrids showed positive female-parent heterosis (FPH) at age 7.5, with the highest relative FPH of 47.2% in D7.5. This study demonstrates the heterosis between inter-sectional species and could have implications for E. urophylla × E. tereticornis hybrid breeding.

Open access
Integration of EST-CAPS markers into genetic maps of Eucalyptus urophylla and E. tereticornis and their alignment with E. grandis genome sequence

Abstract

A suite of 91 expressed sequence tag (EST) derived cleaved amplified polymorphic sequence (CAPS) markers were developed and used for enriching the genetic maps of Eucalyptus urophylla and E. tereticornis built previously based on random amplified polymorphic DNA (RAPD) markers. The EST-CAPS markers were highly similar to original ESTs, with sequence identity ranging from 92.5% to 100.0%. In linkage analysis, 48 and 42 EST-CAPSs were integrated into the genetic maps of E. urophylla and E. tereticornis, respectively, including 13 shared by both maps, while 14 were unmapped. For E. urophylla, the final map had a total length of 1789.5 cM and a mean interval between markers of 9.7 cM, being 284.9 cM larger and 1.3 cM less than those of the prior RAPD map, respectively. For E. tereticornis, the final map had a length of 1488.1 cM and a mean interval of 10.3 cM, being 452.4 and 0.2 cM more than the prior map, respectively. All the 77 newly mapped EST-CAPSs found each at least one homologue in the E. grandis genome sequence released recently, and conserved synteny and colinearity were observed between E. grandis genome and our linkage groups. The enriched maps would provide a set of useful markers for genome analysis, comparative mapping and fine-mapping of important genes located in conserved regions for the important tree genus Eucalyptus.

Open access
Comparative Analysis of the Empirical Seismic Vulnerability of Typical Structures in Multiple Intensity Zones

Abstract

To study the difference in seismic vulnerability of multiple typical structures in multiple intensity zones, the seismic damage of 7099 buildings of Dujiangyan masonry structure (MS), reinforced concrete structure (RC) and bottom frame seismic wall masonry (BFM) in the 2008 Wenchuan earthquake in China is summarized and analysed. First, a statistical analysis of the data is carried out, the empirical seismic vulnerability matrix and model curves are established by considering the number of storeys, the age and the fortification factors. The vulnerability curves of the cumulative exceeding probability of the empirical seismic damage and the grade of the seismic damage in multiple intensity zones are shown. The mean damage index vulnerability matrix model is proposed and verified using the empirical seismic damage matrix of typical structures.

Open access