Analysis of SSR loci and development of SSR primers in Eucalyptus

In this study,28,691 genome sequences and16,566 expressed sequence tags(ESTs) of Eucalyptus were derived from the Gen Bank database.A total of 2292 SSR loci were sought out from 1785 effective sequences.Through analyses of SSR loci information,the SSR motif length was negatively correlated with the abundance of the SSRs.In the EST sequences of Eucalyptus,triplet repeat motifs were the most abundant,and dinucleotide repeats motifs had the highest frequencies.Subsequently,395 pairs of primers were designed based on the SSR loci.Using optimized SSR-PCR conditions,340 pairs of primers were successfully screened,with a success rate of 86.1%.By construction of a maximum likelihood phylogenetic tree of six eucalypt species,represented by five species of the genus Eucalyptus and one of the genus Corymbia,the genetic relationships of Eucalyptus urophylla and E.camaldulensis suggested by this tree was found to differ from that suggested by traditional morphological taxonomy.The results provide insights for evaluating geneticdiversity of Eucalyptus and analysis of Eucalyptus phylogenetics using SSR markers.

Advances in eucalypt research in China

Eucalypt plantations in China currently exceed4.5 Mhm^2, and this country has the third largest area of such plantations after India and Brazil. China's eucalypt industry now comprises a complex, multifaceted industry including seedling propagation, fertilizer production and supply, plantation silviculture, harvesting and transport,wood processing for products including lumber, pulp and paper, and wood-based panels, as well as bioenergy production and various forest byproducts and non-wood forest products. In 2015, the combined value of output of this whole industry was around 300 billion CNY. Chinese research and development(R&D) has been instrumental in supporting growth and development across the whole breadth of the country's eucalypt industry. In this report,recent advances in this R&D are reviewed under six key topics:(1) advanced propagation technology;(2) genetic resources and breeding;(3) targeted silviculture;(4) eucalypt disease and pest management;(5) enhancing plantation ecology and sustainability; and(6) wood processing and byproduct technology. R&D has greatly facilitated expansion and proliferation of all parts of China's eucalypt industry. This industry is now of major importance to China's economy; it involves tens of thousands of growers and companies that provide livelihoods for hundreds of thousands of people.

Taxonomy and pathogenicity of Ceratocystis species on Eucalyptus trees in South China, including C. chinaeucensis sp. nov.

Commercial plantations of Eucalyptus species have been established in South China,especially during the past 20 years,to meet the needs of a rapidly growing national economy.As part of a survey of fungal diseases affecting Eucalyptus species in South China,Ceratocystis species were collected from Eucalyptus plantations in the GuangDong Province.The aims of this study were to identify these Ceratocystis isolates and to test their pathogenicity to Eucalyptus.The most aggressive isolates were also used to screen different species and clones of Eucalyptus for susceptibility to infection under field conditions.The fungi were identified based on morphology and through comparisons of DNA sequence data of the ITS,partialβ-tubulin and TEF-1αgene regions.Morphological and DNA sequence comparisons showed that isolates collected from Chinese Eucalyptus plantations represent two species,C.acaciivora in the C.fimbriata s.l.species complex and a previously undescribed species belonging to the C.moniliformis s.l.species complex,for which the name C.chinaeucensis sp.nov.is provided.In pathogenicity trials,both C.acaciivora and C.chinaeucensis gave rise to lesions on wounded Eucalyptus trees,and the former fungus was most pathogenic.Differences were also observed in the responses of different Eucalyptus clones to inoculation and this could be useful in reducing disease,if C.acaciivora should emerge as a pathogen in the future.