Embryo Culture, In Vitro Propagation, and Molecular Identification for Advanced Olive Breeding Programs

The high biodiversity of the olive tree is an important opportunity to develop sustainable plans to control Xylella fastidiosa (Xf) through breeding programs. Olive tree breeding activities have been limited due to various features of this species including the long time required for seed germination caused by the inhibition effect of the woody endocarp, the seed integument, and the endosperm. Starting from F1 seeds by cross-breeding, the embryo culture was compared with traditional seed germination, evaluating the effectiveness of in vitro multiplication of the plantlets for large-scale production. The isolated embryos were established on a new medium based on Rugini ‘84 macroelements, Murashige & Skoog ‘62 microelements, with Nitsch J. P. & Nitsch C. ‘69 vitamine and subcultured on Leva MSM modified. The results obtained confirmed that in vitro culture of olive embryos is a valid tool for increasing the percentage and speed of germination, helping to reduce the time of the olive breeding programs, offering the possibility to effectively propagate plantlets for further experiments.

Unravelling Rubber Tree Growth by Integrating GWAS and Biological Network-Based Approaches

Hevea brasiliensis (rubber tree) is a large tree species of the Euphorbiaceae family with inestimable economic importance. Rubber tree breeding programs currently aim to improve growth and production, and the use of early genotype selection technologies can accelerate such processes, mainly with the incorporation of genomic tools, such as marker-assisted selection (MAS). However, few quantitative trait loci (QTLs) have been used successfully in MAS for complex characteristics. Recent research shows the efficiency of genome-wide association studies (GWAS) for locating QTL regions in different populations. In this way, the integration of GWAS, RNA-sequencing (RNA-Seq) methodologies, coexpression networks and enzyme networks can provide a better understanding of the molecular relationships involved in the definition of the phenotypes of interest, supplying research support for the development of appropriate genomic based strategies for breeding. In this context, this work presents the potential of using combined multiomics to decipher the mechanisms of genotype and phenotype associations involved in the growth of rubber trees. Using GWAS from a genotyping-by-sequencing (GBS) Hevea population, we were able to identify molecular markers in QTL regions with a main effect on rubber tree plant growth under constant water stress. The underlying genes were evaluated and incorporated into a gene coexpression network modelled with an assembled RNA-Seq-based transcriptome of the species, where novel gene relationships were estimated and evaluated through in silico methodologies, including an estimated enzymatic network. From all these analyses, we were able to estimate not only the main genes involved in defining the phenotype but also the interactions between a core of genes related to rubber tree growth at the transcriptional and translational levels. This work was the first to integrate multiomics analysis into the in-depth investigation of rubber tree plant growth, producing useful data for future genetic studies in the species and enhancing the efficiency of the species improvement programs.

Conifers: Species Diversity and Improvement Status in Kenya

A wide range of exotic conifer species have been successfully introduced in Kenya since 1910 for the purpose of supplying wood, mainly for timber, pulp, and plywood industries. Among the conifers introduced, Cupressus lusitanica and Pinus patula have adapted well to local growing conditions and are now the key species widely planted in commercial plantations. The other conifer species are planted at secondary level or as ornamentals. In order to increase productivity, the key conifer species have been subjected to genetic improvement through selection, breeding, and hybridization. Results of tree improvement work on C. lusitanica and P. patula showed growth and productivity increase from 20 to 25 m3/ha/yr. for C. lusitanica and from 25 to 30 m3/ha/yr. for P. patula. Scaling up conifer plantations using the tree improvement technologies drawn for the two species is one of the strategies for closing the annual wood supply–demand deficit which is currently estimated at 10.3 million m3. It is also one of the strategies for achieving 10% tree cover which is currently at 7.2%. The strategy encompasses the application of principles of tree breeding, improved germplasm, silviculture, pests and disease control. This presentation is a review of the status of conifer species since their introduction in Kenya.

Prediction ability of genome-wide markers in Pinus taeda L. within and between population is affected by relatedness to the training population and trait genetic architecture

Genomic prediction has the potential to significantly increase the rate of genetic gain in tree breeding programs. In this study, a clonally replicated population (n = 2063) was used to train a genomic prediction model. The model was validated both within the training population and in a separate population (n = 451). The prediction abilities from random (20% vs. 80%) cross validation within the training population were 0.56 and 0.78 for height and stem form, respectively. Removal of all full-sib relatives within the training population resulted in ∼50% reduction in their genomic prediction ability for both traits. The average prediction ability for all 451 individual trees was 0.29 for height and 0.57 for stem form. The degree of genetic linkage (full sib family, half sib family, unrelated) between the training and validation sets had a strong impact on prediction ability for stem form but not for height. A dominant dwarfing allele, the first to be reported in a conifer species, was discovered via GWAS on linkage group 5 that conferred a 0.33 m mean height reduction. However, the QTL was family specific. The rapid decay of LD, large genome size, and inconsistencies in marker-QTL linkage phase suggest that large, diverse training populations are needed for genomic selection in Pinus taeda L.

Accelerating Adaptation of Forest Trees to Climate Change Using Individual Tree Response Functions

In forest tree breeding, assisted migration has been proposed to accelerate the adaptive response to climate change. Response functions are currently fitted across multiple populations and environments, enabling selections of the most appropriate seed sources for a specific reforestation site. So far, the approach has been limited to capturing adaptive variation among populations, neglecting tree-to-tree variation residing within a population. Here, we combined the response function methodology with the in-situ breeding approach, utilizing progeny trials of European larch (Larix decidua) across 21 test sites in Austria ranging from Alpine to lowland regions. We quantified intra-population genetic variance and predicted individual genetic performance along a climatic gradient. This approach can be adopted in most breeding and conservation programs, boosting the speed of adaptation under climate change.

Transcriptome and microRNA Sequencing Identified miRNAs and Target Genes in Different Developmental Stages of the Vascular Cambium in Cryptomeria fortunei Hooibrenk

Cryptomeria fortunei Hooibrenk is an important fast-growing coniferous timber species that is widely used in landscaping. Recently, research on timber quality has gained substantial attention in the field of tree breeding. Wood is the secondary xylem formed by the continuous inward division and differentiation of the vascular cambium; therefore, the development of the vascular cambium is particularly important for wood quality. In this study, we analyzed the transcriptomes of the cambial zone in C. fortunei during different developmental stages using Illumina HiSeq sequencing, focusing on general transcriptome and microRNA (miRNA) data. We performed functional annotation of the differentially expressed genes (DEGs) in the different stages identified by transcriptome sequencing and generated 15 miRNA libraries yielding 4.73 Gb of clean reads. The most common length of the filtered miRNAs was 21nt, accounting for 33.1% of the total filtered reads. We annotated a total of 32 known miRNA families. Some miRNAs played roles in hormone signal transduction (miR159, miR160, and miR166), growth and development (miR166 and miR396), and the coercion response (miR394 and miR395), and degradome sequencing showed potential cleavage sites between miRNAs and target genes. Differential expression of miRNAs and target genes and functional validation of the obtained transcriptome and miRNA data provide a theoretical basis for further elucidating the molecular mechanisms of cellular growth and differentiation, as well as wood formation in the vascular cambium, which will help improve the wood quality of C. fortunei.

Genetic diversity of black mangrove (Rhizophora mucronata Lamk.) based on morphological markers in Maros, Pangkep, and Barru Provenances

Mangrove forests are tropical and subtropical forests that grow typically along the coast or river estuaries. Black mangroves are a type of mangrove found in South Sulawesi, precisely in Maros, Pangkep, and Barru Districts. The decline in black mangrove populations overcomes the threat limit to germplasm which can lead to reduced genetic diversity in black mangrove plants. To reduce the incidence of extinction in black mangroves, information on genetic diversity using one of the markers is required, namely morphological markers in taking samples of tree parts taken, namely the leaves, stems, and roots which are then for monitoring carried out in the Biotechnology Laboratory and tree breeding. The method used in this study is based on the literature on the development of the Tropical Fruit Descriptor information system. The results of the three studies proved that there is a difference between the evidence and the interprovenencies. The very close morphological kinship between them proved to be found in Pangkep. Pangkep’s provenance has a high coefficient compared to the proof of Maros and Barru, which is at the time level of 70%, while the proof of Maros has the lowest coefficient compared to the proof of Barru and Pangkep, which is at the gathering level of 64%.

Detection of pebrine disease and Bombyx mori Nuclear Polyhedrosis Virus (BmNPV) in silkworm moths (Bombyx mori. L)

Silkworm is an insect that can produce silk fiber at any step of life, one of them in the moth phase. There are still not many researchers who have researched pebrine and BmNPV disease detection in the moth phase. This research purpose was to find out pebrine and BmNPV disease detection on moth phase. This research was conducted from January 2021 to March 2021 with samples obtained from the Center for Social Forestry and Environmental Partnership, South Sulawesi in Bili-Bili, Gowa district. The data processing was done at the Laboratory of Biotechnology and Tree Breeding, Faculty of Forestry, Universitas Hasanuddin, Makassar. Data analysis was done using the descriptive analysis method by looking at the primer amplification of Pebrine disease and BmNPV in the silkworm moth phase. The detection of pebrine disease ad BmNPV from the two primers showed that from 12 moths studied, none of the moths detected either pebrine disease or BmNPV disease.

Review: Utilization of interspecific Acacia hybrid for pulp/paper industry and increasing of forest biodiversity

Wood-based forestry industries are one of the strategic sectors in the development for providing a good impact in ecological and socio-economic in a country. Such an industry should have high productivity in order to ensure sustainable resources and an efficient manufacturing process. Based on this fact, tree breeding program is one of the good practices which could be done through the hybridization method to increase the uses from forest genetic resources. This paper presents a review on the basis of the utilization of inter-specific Acacia hybrids resulted from hybridization between two species of Acacia mangium and Acacia auriculiformis for supporting the pulp/paper industry and increasing the forest biodiversity in Indonesia. Improving some traits relevant to the industrial requirements is the main target in the development of Acacia hybrid. This involves fast growth, good wood properties, and tolerance to pests and diseases. The Acacia hybrids could provide some advantages in overcoming the current problems of the forest plantation and industry in which some of them could not be resolved by planting the pure species. In addition, the varies of the Acacia hybrid progenies could be used to increase forest biodiversity, which is important as a genetic base for further breeding purposes and challenges.

Study on the genetic diversity of wax trees (Rhus succedanea L.) in Northern mountainous region of Vietnam by SSR and SCoT markers

Wax tree has been cultivated to get lacquer, a valuable source of material that is necessary for many industries and handicrafts. Evaluating not only phenotype but also genotype is essential in order to increase the efficiency of new breeding program. In this study, the genetic relationship at the molecular level of 90 wax trees collected in three regions, i.e., Tam Nong, Thanh Son (Phu Tho) and Chiem Hoa (Tuyen Quang), was analyzed by SSR and ScoT markers. The results revealed a significant diversity among the individuals, with similarity coefficient from 0.41 to 0.98. The sample group collected in Chiem Hoa was significantly different from that in Tam Nong. Most of samples which had a high level of genetic similarity, from 0.95 to 0.98, were pairs of samples at the same geographical origin. The high similarity degree of these samples is likely due to the practice of selecting seeds from high-yield wax tree to be kept for seeds. These results provide the necessary information for new wax tree breeding program.