Progeny Of Trees Research Articles

Opportunities for the Early Diagnosis and Selection of Scots Pine with Potential Resistance to Root and Butt Rot Disease

Pine stands affected by root and butt rot (Heterobasidion annosum s.l.) contain pines (Pinus sylvestris L.) that can survive for a long time without showing external symptoms of the disease (‘conditionally resistant’ refers to trees that survive without symptoms despite infection). The establishment of stands from the seeds of such trees can significantly increase the effectiveness of artificial afforestation. Since the growth and development of pine trees is determined to a certain extent by the number of cotyledons after seed germination, this article examines this trait in the progeny of trees that are potentially resistant and those that have already been attacked by root pathogens. The number of cotyledons and the resilience of trees is fascinating and not generally known. Presumably, the number of cotyledons can be linked to disease resistance based on increased vigour. Biologically, a larger area for carbon assimilation leads to better photosynthetic efficiency and the production of more assimilates (sugars) necessary to trigger defence processes in the event of infection. From an ecological point of view, this can give tree populations in areas potentially threatened by root system diseases a chance of survival. The aim of this study was to analyze the potential of using the number of cotyledons and other seedling characteristics to predict the resistance of trees to root and butt rot disease. The collected data show that the seedlings from the group of diseased trees exhibited lower growth rates and vigour. However, the seedlings from the group of potentially resistant trees are similar to the control, meaning the trees that show no disease symptoms because they have not come into contact with the pathogen. Our observations suggest that monitoring germinating cotyledons could serve as an early diagnostic tool to identify disease-resistant pines, although further research is needed.

Фенотипическая оценка клонов плюсовых деревьев сосны обыкновенной (Pinus sylvestris L.) в лесостепной зоне Башкирского Предуралья

An assessment of the main morphometric features of the ramets of clones of Scots pine plus trees in a comparative aspect has been carried out. The vegetative progeny of plus trees of the species are represented as part of a clonal plantation created in 2005 in the Dyurtyulinskiy forestry of the forest-steppe zone of the Republic of Bashkortostan in an area with the С2 type of forest growing conditions. Compliance with the breeding and genetic principle of phenotypic assessment of intraand intergroup differences in Scots pine clones and ramets, as well as methodical and methodological requirements for conducting the field stage of the study, has been ensured. Taxation indicators (the height and diameter of the stem, the diameter and length of the crown, the increment of the central shoot in height) have been taken into account for 100 clones at a continuous count. A varying nature of the distribution of the average values of the analyzed stem indicators in the vegetative progeny of plus trees has been revealed. The best growth in stem diameter (25.5±0.73 cm) and height (11.2±0.16 m), as well as central shoot increment (0.45±0.02 m), are typical for the progeny of clones of the plus tree 29/17. Clones 263/40, 264/41, 262/39 with taxation indicators above the average for the entire set of trees in the clone archive are of high breeding value, which indicates the specificity of the genotypes of these specimens. The levels of significance of the differences and the intensity of selection of the best clones of plus trees based on morphometric features have been determined, which indicates the different nature of the individual non-identity of each of the plus trees relative to the rest of the trees studied. The valuable genotypes of the progeny of Scots pine plus trees identified in the clone archive can be recommended for further use in forest seed breeding when creating highly productive and sustainable artificial plantations of this valuable tree species in the region.

Архивы клонов плюсовых деревьев сосны обыкновенной в Республике Карелия

Archives of clones (ACs) of plus trees (PTs) are laid to preserve their genotypes. The genotype of each plus tree is unique, and its loss is irreplaceable. In addition, scientific observations are carried out in the archives, in particular, the selection of clones for forest seed orchards (FCOs) of increased genetic value (FSO-I,5). The aim of this research has been to study the dynamics of creating and preserving the archives of clones, as well as their state, in Russia in general and in the Republic of Karelia in particular. As of 2019 there were 31,514 plus trees in the Russian Federation, and the archives of clones covered an area of 573.6 ha, or 17 % less than in 1976. In the Republic of Karelia, despite discarding 40 % of them, as of 01.01.2023, there were 1,486 plus trees, including 1,100 trees of the most valuable forest species – Scots pine. Only 12.8 % of the progeny of this species grow in the archives of clones (8.4 % of a total of 1,695 selected Scots pine plus trees). For a full-fledged archive of clones (1,695 pcs. of the progeny of Scots pine plus trees), it is required to additionally plant 38.9 ha (in two repetitions – 81.3 ha) of trees. First of all, it is necessary to create the archives of clones of Scots pine from the plus trees listed in the register of the Republic of Karelia as of 2023 (1,110 pcs.). In this case, the area of additional planting will be 52 ha. To date, the selection inventory of forests in Russia as a whole and its regions, including the Republic of Karelia, has been partially completed, i.e. the selection of plus trees, considering the huge size of forested area, has also been carried out to a limited extent. Meanwhile, it is the plus plantations, plus trees and forest seed orchards created by their clone progeny that are a sample of the best phenotypic gene pool of the main forest-forming species, both in the regions of the RF and in the country as a whole. But over time these objects are aging, dying and being cut down. The best specimens may not always be preserved even in forest seed orchards and matrix plantations (MPs). Constant deforestation, a decrease in the age of felling, and the natural aging of certified plus tress necessitate the resumption of systematic selection of plus trees in the best ripening plantations of the Republic, especially its northern and central parts, and the cultivation of the best trees in the archives of clones in the form of clone progeny. This article indicates the importance of clone archives for preserving the valuable gene pool of forest woody plants and their use even in the event of the disappearance of plus trees in the places of selection and registration.

Variability Study Analysis for Half-sib Families under Control Environmental Conditions in Neolamarckia cadamba (Kadamb)

Neolamarckia cadamba is a widespread medium-sized deciduous forest tree over most of India, Bangladesh, and Sri Lanka. Twenty-half-sib progenies of kadamb (Neolamarckia cadamba) from various regions in Bihar, Rajasthan, and Uttar Pradesh were sown in a glasshouse in 2022 in order to assess the genetic diversity using non-hierarchical Euclidean cluster analysis. Significant variation was seen in the biomass and morphological traits of a few plus trees. Under greenhouse conditions, significant differences were seen in the growth parameters of plus tree progenies. Six clusters were formed from the twenty NPTs, according to the genetic divergence analysis. Clusters V and VI were found to have the greatest inter-cluster distance (5.530). The cluster (4.258) displayed the highest intra-cluster distance. As a result, there was a genetic divergence between clusters. Therefore, in order to obtain high-yielding genotypes in Neolamarckia cadamba, hybridization involving trees of clusters VI and V is advised. Collar diameter was a major factor in the creation of genetic diversity and contributed the most to the overall divergence. The superior plus trees of cluster V (NPT4, NPT5, NPT11, NPT12, NPT13, NPT17) and cluster VI (NPT18, NPT19, NPT20) may be taken into consideration as possible parents for a future tree improvement program in Neolamarckia cadamba due to their high cluster mean and large genetic distance.

Correlation Studies for Morphological and Biomass Traits in Half-sib Progenies of Peltophorum pterocarpum

The current research was conducted on twenty plus trees of Peltophorum pterocarpum from different locations in Bihar to study the association among different morphological and biomass traits. It was found that PPT12 (Rajgir Park) and PPT4 (Muraura, Nalanda) performed better for germination metrics under open field and greenhouse conditions, respectively. PPT6 (Nari, Nalanda) and PPT13 (Sathopur, Nalanda) outperformed all other superior tree progenies in terms of morphological and biomass attributes in green house and open field conditions, respectively. The phenotypic coefficient of variability was greater than the genotypic coefficient of variability for all morphological and biomass variables tested under green house and field conditions, showing that the environment played a greater role. Germination value heritability was found to be high in both environments. High heritability with high genetic advance was associated with shoot length in greenhouse condition, indicating additive gene action. Under greenhouse conditions, the phenotypic correlation coefficients among the seedling parameters evaluated varied from a non-significant 0.211 (P=0.01) between shoot root ratio and root dry weight and between shoot length and collar diameter to a very significant 0.967 (P=0.01).Accessions showing higher values for one or the other attributes could be selected as parents for further improvement.

The growth rate and genetic variability of Scots pine (Pinus sylvestris L.) half-sibs in test crops of Northern Kazakhstan

Scots pine (Pinus sylvestris L.) is a valuable tree species, playing an important role in maintaining the ecological and economic balance not only in Kazakhstan, but also in many countries around the world. The purpose of this study was to assess the growth rate and to identify the genotypes of the half-sib progeny of Scotch pine plus trees in order to further obtain high-quality seeds with valuable genetic traits. A molecular genetic analysis was carried out using six microsatellite and 20 isoenzyme loci on 15 Scots pine half-sib families, represented by two samples of seeds collected in the subsequent harvesting periods (planted in 1986 and 1987), that evaluated the taxonomic characteristics such as tree height and trunk diameter (DBH, measured at 1.3 meters). Families with the highest growth rate in both samples were selected as candidates for the elite group. During the SSR analysis, a decrease in the level of expected heterozygosity (0.2377-0.5362 with an average value of 0.4593) was observed in P. sylvestris L. half-sibs compared to the sample of maternal plus trees (0.5444), with similar results to that of the “founder effect”. At the same time, the level of observed heterozygosity remained sufficiently high (0.3333-0.7037 with an average value of 0.4980 and 0.4556, respectively). During the isoenzyme analysis, the level of genetic variability either decreased or was similar to that of the maternal trees. Rare and unique alleles were found in seed samples of the analysed tree families. In general, this research showed that a comprehensive evaluation combining both traditional breeding methods (genetic assessment of progeny in the course of growth) and molecular genetic analysis is required for the selection of elite trees.

Frost hardiness of Finnish plus tree progenies of Scots pine from seed orchards in Finland and Ukraine

To avoid the surrounding pollination, seed orchards of Finnish plus trees have been established in Ukraine, i.e., far from their natural distribution. However, it is unknown whether the pollination site affects the frost hardiness (FH) of the progenies and thus their use in forest regeneration in Finland. Using whole-plant freezing tests, we examined the FH of plus tree seed orchard progenies in Finland and Ukraine, with three lots of seeds from each orchard, twice during cold acclimation in controlled conditions. The FH of needles, as assessed immediately after the freezing tests, was higher in the Finnish than Ukrainian seed orchard progenies. The variation in the FH of needles was high among the progenies, ranging from − 44 to − 79 °C by relative electrolyte leakage (REL), and from − 29 to − 46 °C by chlorophyll fluorescence (CF). However, when FH was assessed based on the growth of shoots and roots in the greenhouse after three weeks, the differences between the progenies and orchards disappeared. The FH was then between − 10 and − 15 °C based on shoot growth, between − 6 and − 12 °C based on root growth, and between − 8 and − 16 °C based on the number of new root tips. The results imply an epigenetic effect on FH of needles but no effect of progeny or orchard on FH of roots. In summary, it seems to be possible to use seed produced in southern Ukraine in practical reforestation actions in southern Finland.

Karyological Study of the Isolated Scots Pine (<i>Pinus sylvestris</i>) Population of the Shirinskaya Steppe of the Republic Of Khakasia

The results of a karyological study of a peripheral isolated population of Scots pine (Pinus sylvestris L.) growing in the Shirinskaya steppe of Khakassia are presented. In the seed progeny of trees, disturbances of the number of chromosomes (myxoploidy) and a wide range of chromosomal rearrangements, including unique multiple aberrations, were revealed. For the first time at the population level, the highest occurrence of genomic and chromosomal rearrangements for this species was diagnosed. In fact, all seed progeny of the studied Scots pine population is mutant, which indicates probable adaptive changes in genotypes under isolation.

Изменчивость репродуктивного развития полусибов плюсовых деревьев Pinus sibirica Du Tour

Selection of Pinus sibirica Du Tour plus trees by seed productivity, breeding of half-sibs, characterized by an abundance of cones and pollen, serve as the basis for the creation of high-yielding target plantations. The aim of the research was to select families with a large percentage of early reproductive development's trees, and specimens with a lot of cones and shoots with male inflorescences. Also, to select specimens in different families of Pinus sibirica Du Tour plus trees by early reproductive development, taking into account the formation of cones and pollen. The subject of the study was the seed progeny of Pinus sibirica Du Tour trees at biological age of 31-35 years, grown on the territory of the arboretum of Reshetnev University, the site «Prodolzhenie geoshkoly» (N 55.9666666667, E 92.6166666667, 287 meters above sea level). Initially, five plus trees growing in Irkutsk (60/24) and Novosibirsk regions (98/62, 102/66, 106/70 and 110/74) for reproduction among certified plus trees by seed productivity were selected. The growing conditions and indicators of plus trees from the certificate drawn up by the commission during their certification are given. Cones from these trees were collected, then seeds were sown and planting material was grown, which was transplanted to the site of the arboretum of Reshetnev University. In 2018, 2021 and 2022, the number of cones and microstrobiles in early reproductive development semis by using binoculars was determined. The variability by early reproductive development of half-sibs in the formation of cones both between families of plus trees (7.8-25.3 psc.), and within families (60/24 – 2-22 psc.; 98/62 – 2-115 psc.; 102/66 – 4-45 psc.;106/70 – 1-54 psc.; 110/74 – 1-15 psc.) is noted. The selection of specimens by the size of the cones was not carried out. Some specimens formed both cones and pollen: 82-7, 85-10 and 87-13 in the family of the plus trees 60/24; 72-11, 79-2, 79-3, 79-4, 79-8, 80-3, 81-4, 85-22 (family 98/62); 83-1,83-6, 83-9, 84-2, 84-4, 86-9, 86-1 (family 102/66); 78-3, 78-9, 81-8, 81-9, 81-10, 85-19 (family 106/70); 79-9, 84-12, 86-5 (family 110/74). Selected specimens have a huge value and can be widely used in their vegetative reproduction and the creation of high-yielding plantations of early reproductive development.

Cytogenetic and Biochemical Characteristics of Callus <i>Pinus sylvestris</i> L.

A comprehensive assessment was carried out of the changes occurring during the darkening of the callus obtained from vegetative buds of 40-year-old Scots pine treesPinus sylvestrisL. Based on biometric assessment of callus (intensity of callus formation, proportion of light callus, callus mass) from 32 analyzed trees (16 genotypes represented by two clones), two genotypes with high callus-forming ability were singled out. Analysis of mitosis showed that, although the proportion of aberrant cells in the callus does not exceed the rate of spontaneous mutation forP. sylvestris, the range of violations at the stage of meta-, ana-, and telophase in the callus culture was wider compared to that in the seed progeny of the same pine trees. Darkening of the callus was accompanied by a decrease in sucrose metabolism in the cell (decrease in cytoplasmic, vacuolar invertase and sucrose synthase) and a significant decrease in peroxidase activity. At the same time, the activity of apoplast invertase was maintained at a constant level. The activity of superoxide dismutase, catalase, polyphenol oxidase, and phenylalanine ammonia lyase, on the contrary, was higher in dark callus. The possible use of the studied enzymes as biochemical markers of the transition to darkening callus pine crops is discussed.

Norway spruce somatic embryogenesis benefits from proliferation of embryogenic tissues on filter discs and cold storage of cotyledonary embryos.

Vegetative propagation opens opportunities for the multiplication of elite tree progeny for forest regeneration material. For conifers such as Norway spruce (Picea abies) the most efficient vegetative propagation method is seed multiplication through somatic embryogenesis. Efficient culture methods are needed for somatic embryogenesis to be commercially viable. Compared to culturing as clumps, filter disc cultures can improve the proliferation of embryogenic tissue (ET) due to more even spread and better developmental synchronization. In this study, ET proliferation on filter discs was compared to proliferation as clumps. The study comprised 28 genotypes in four trials. The benefits of adding a pre-maturation step and the selection of fresh ET for the subculture were evaluated. Pre-maturation on hormone-free media before maturation did not significantly improve embryo yield but improved greenhouse survival from 69% to 80%, although there was high variation between lines. Filter disc cultivation of ET did result in better growth than in clumps but was more dependent on ET selection and the amount of ET than the clump cultivation method. Filter proliferation also favors certain lines. Post-maturation storage can be used to change the storage compound composition of the produced mature embryos. The embryo storage compound profile was analyzed after post-maturation cold storage treatments of 0, 4, 8, 31, and 61 weeks and compared to that of the zygotic embryos. Cold storage made the storage compound profile of somatic embryos closer to that of zygotic embryos, especially regarding the raffinose family oligosaccharides and storage proteins. Sucrose, hexose, and starch content remained higher in somatic embryos even through cold storage. Prolonged storage appeared less beneficial for embryos, some of which then seemed to spontaneously enter the germination process.

Genetic variability of traits of the laticiferous system and association with rubber yield in juvenile and adult rubber tree progenies

The objectives of this study were to investigate genetic variation and association of the traits of the laticiferous system with rubber yield in young and adult rubber tree progenies Hevea brasiliensis, and compare the traits of the laticiferous system at different heights of the adult trees. The genetic material is composed of progenies from open pollination from the rubber tree breeding program of IAC, evaluated in the experimental field of UNESP in Ilha Solteira, SP, Brazil, in the young and adult phases, and in the Polo Regional Alta Mogiana of the Agência Paulista de Tecnologia do Agronegócio in Colina, SP, Brazil in the young phase. A randomized block experimental design was used with 30 treatments (progenies), three replications, and 10 plants per plot. The following traits were evaluated: rubber yield (RY), virgin bark thickness (BT), number of rings of laticiferous vessels (NR), and mean distance between consecutive rings of the laticiferous vessels (MD). The individual statistical analyses and repeated measurements were performed through mixed linear models using the REML/BLUP (Restricted Maximum Likelihood/Best Linear Unbiased Prediction) procedure. Genetic and phenotypic correlations were also estimated. The accuracy estimates (Aˆc) for the traits in the two locations were higher (> 0.7), indicating good perspectives in a breeding program. The coefficient of genetic variation (CVg %) showed low variation between the sites: BT (4.5–7 %), NR (14.1–18.3 %), and MD (15–18.2 %). The NR expressed higher heritabilities and was therefore the best trait of the laticiferous system for predicting genetic values; it showed expressive genetic correlations with RY, and may be used in indirect selection. BT did not show progeny × height interaction, indicating that the classification of the progenies was the same, regardless of the tree height at collection. To select progenies in common in the young and adult ages, using analysis of measurements repeated in time, the most suitable height for collection of samples in the adult progenies for the traits of the laticiferous system was up to 80 cm. The traits of the laticiferous system collected at 30 cm in young progenies are associated with RY, both in the youth phase and in the adult phase. They can be used to assist in early or indirect selection of rubber tree progenies.

Status of Nitrogen in Different Parts of Cupuassu Tree in Oriental Amazon

Despite the socio-economic importance of the cupuassu tree for the Amazon region, a few studies have aimed to evaluate the nutritional status of nitrogen in cupuassu plantations, especially in the different vegetative parts. Thus, this research aimed to quantify the content and accumulation of nitrogen in vegetative parts of two progenies of cupuassu trees in the Amazon region. The experiment was carried out in an area of intercropping cupuassu tree x açai palm x banana, at Embrapa Amazônia Oriental, located in Belém, in the state of Pará from 2003 to 2007. The experimental design adopted was completely randomized in a 2 x 4 x 4 factorial scheme with two progenies (PMI 186 (Codajás) and a PMI 215 (Manacapuru)) x four years of evaluation and four plant components (leaves, stems, primary branches and secondary branches) with five replications, in which each experimental unit was composed of a plant from each progeny. The two PMI(s) present nitrogen storage in the secondary branches, but the PMI 186 presented higher N accumulation than the PMI 215. N content was higher in the leaves in both progenies independent of the plant age, with values over 50% of the total content. Therefore, Cupuassu tree progenies under intercropping showed satisfactory N accumulations throughout the study. It can be concluded that it is being viable options in intercropping in agroforestry systems.

Цитогенетическая характеристика семенного потомства клонов плюсовых деревьев сосны обыкновенной в Карелии

The article describes the cytogenetic parameters of seed progeny of Pinus sylvestris plus trees growing in the Petrozavodsk seed orchard of the first order. P. sylvestris normal trees from the natural pine phytocenosis in the Pryazha region (Karelia) were taken as a control. The following indicators were considered: relative DNA content, number of chromosomes, frequency and types of mitosis pathologies at the metaphase, anaphase and telophase stages (in % of the total number of dividing cells at the same stages). It was found that the root meristem of the P. sylvestris seed progeny contains 24 chromosomes in the diploid set. Single aneuploid cells (2n = 23; 2n = 25) were found in the studied plants. The most frequent is monosomy (2n = 23). It made up 81 % of the total number of aneuploid cells. The relative DNA content in the young needles of pine seedlings of plus clones and normal trees was 42.07±0.21 and 42.95±0.04 pg, respectively, and the difference between the two was statistically significant (U-test, p ˂ 0.01). Cytogenetic analysis revealed 7 types of mitosis pathologies: chromosome fragmentation, chromosome bridges, chromosome overlap, isolation of chromosomes and groups of chromosomes, chromosome lagging, multipolar mitosis and complex abnormalities. Chromosome overlap was the most common pathology in the general mitotic disorders spectrum. Comparison of mitosis pathologies in two general samples of normal trees and plus tree clones showed that they significantly differ by the following mitosis abnormalities: overlap and isolation of chromosomes in metaphase, fragmentation, lagging, bridges and multipolar mitosis in the anaphase and telophase. The study shows that the proportion of cells with mitosis abnormalities in the seed progeny of normal trees was about 1.5 times higher than of plus tree clones, and is equal 3.44±0.32 and 2.38±0.14 % (U-test, p = 0.05), respectively. The data obtained demonstrate the cytogenetic stability of the seed progeny of P. sylvestris clones from the Petrozavodsk seed orchard of the first order, which in turn may indicate the high quality of the seed material. For citation: Ignatenko R.V., Ershova M.A., Galibina N.A., Raevsky B.V. Cytogenetic Characteristics of Seed Progeny of Scots Pine Plus Tree Clones in Karelia. Lesnoy Zhurnal [Russian Forestry Journal], 2022, no. 1, pp. 9–22. DOI: 10.37482/0536-1036-2022-1-9-22

Stability of Transgene Inheritance in Progeny of Field-Grown Pear Trees over a 7-Year Period.

Breeding woody plants is a very time-consuming process, and genetic engineering tools have been used to shorten the juvenile phase. In addition, transgenic trees for commercial cultivation can also be used in classical breeding, but the segregation of transgenes in the progeny of perennial plants, as well as the possible appearance of unintended changes, have been poorly investigated. We studied the inheritance of the uidA gene in the progeny of field-grown transgenic pear trees for 7 years and the physical and physiological parameters of transgenic seeds. A total of 13 transgenic lines were analyzed, and the uidA gene segregated 1:1 in the progeny of 9 lines and 3:1 in the progeny of 4 lines, which is consistent with Mendelian inheritance for one and two transgene loci, respectively. Rare and random deviations from the Mendelian ratio were observed only for lines with one locus. Transgenic seeds’ mass, size, and shape varied slightly, despite significant fluctuations in weather conditions during cultivation. Expression of the uidA gene in the progeny was stable. Our study showed that the transgene inheritance in the progeny of pear trees under field conditions occurs according to Mendelian ratio, does not depend on the environment, and the seed vigor of transgenic seeds does not change.

Cytogenetic characteristics of seed progeny of old-aged trees of Pinus pallasiana and Picea abies (Pinaceae)

Information on cytogenetic changes in the seed offspring of old-aged trees is insufficient and inconsistent. In our studies, 150–200-year old trees of Picea abies and Pinus pallasiana were used. We analyzed peculiarities of their karyotype, nucleus-forming region, and nucleolus in the cells of seedlings of P. abies and P. pallasiana emerged from seeds in natural populations and plantations of introduced plants. As a result, age-dependent cytogenetic disorders were observed, such as the chromosome bridges, lag, premature segregation, and agglutination. Peculiarities with regard to number and structure of secondary chromosome constriction are demonstrated. The identified properties of the cell structure of seeds of old-aged trees of P. abies and P. pallasiana indicate that more resources are needed to maintain their protein synthesis at a normal level. The increased number of abnormalities indicates a significant impact of accumulated intracellular metabolites and cytopathological phenomena in mother plants on the quality of seed offspring.

Genome-wide high-resolution mapping of DNA methylation reveals epigenetic variation in the offspring of sexual and asexual propagation in Robinia pseudoacacia.

We detected the genome-wide pattern of DNA methylation and its association with gene expression in sexual and asexual progenies of mature Robinia pseudoacacia trees. DNA methylation plays an important role in plant reproduction and development. Although some studies on sexual reproduction have been carried out in model plants, little is known about the dynamic changes in DNA methylation and their effect on gene expression in sexual and asexual progeny of woody plants. Here, through whole-genome bisulfite sequencing, we revealed DNA methylation patterns in the sexual and asexual progenies of mature Robinia pseudoacacia to understand the regulation of gene expression by DNA methylation in juvenile seedlings. An average of 53% CG, 34% CHG and 5% CHH contexts was methylated in the leaves of mature and juvenile individuals. The CHH methylation level of asexually propagated seedlings was significantly lower than that of seed-derived seedlings and mature trees. The intergenic regions had the highest methylation level. Analysis of differentially methylated regions (DMRs) showed that most of them were hypermethylated and located in the gene upstream and introns. A total of 24, 108 and 162 differentially expressed genes containing DMRs were identified in root sprouts (RSs), root cuttings (RCs) and seed-derived seedlings (SSs), respectively, and a large proportion of them showed hypermethylation. In addition, DMRs were enriched within GO subcategories including catalytic activity, metabolic process and cellular process. The results reveal widespread DNA methylation changes between mature plants and their progenies through sexual/asexual reproduction, which provides novel insights into DNA methylation reprogramming and the regulation of gene expression in woody plants.

Application of retrotransposon-based Inter-SINE Amplified Polymorphism (ISAP) markers for the differentiation of common poplar genotypes

On the basis of retrotransposon-insertion polymorphisms, molecular markers were developed for the identification and differentiation of poplar (Populus spp.) genotypes. For this purpose, short interspersed nuclear elements (SINEs) in the genome sequence of Populus tremula L. were identified and assigned to different SINE families. For families with high copy number and high identity values, primers were developed to amplify inter-SINE amplified polymorphisms (ISAPs) with polymerase chain reaction. The resulting fragments produce genotype-specific fingerprints. This molecular approach utilizes standard laboratory equipment and is therefore easy to use for the verification of plant material. We demonstrate the functionality of three distinct ISAP primer combinations in comparison with 10 simple sequence repeat markers to differentiate 23 poplar genotypes. Already by using a single ISAP primer combination, all genotypes could be clearly distinguished. Furthermore, the cluster analysis based on three primer combinations divided clones according to their genetic background into two subclusters (by a bootstrap value of 98). Our results clearly demonstrate the usability of ISAP markers to differentiate genotypes and trace progenies of poplar trees.

Calidad de plántula de árboles seleccionados de leucaena esculenta en sistema agroforestal

En condiciones de invernadero se evaluó la calidad de plántulas de progenies selectas de Leucaena esculenta. En este sentido, durante 2017 se estudió el crecimiento de plantas en función de progenies de árboles y edad después de la siembra (DDS) realizando análisis de varianza y pruebas de medias (Duncan, 0.05). Las progenies y los DDS mostraron separadamente diferencias significativas (p ≤ 0.0001) en las variables morfológicas y área foliar. Los índices de calidad fueron diferentes entre árboles (progenies) y DDS, donde el árbol 9 tuvo el valor mayor (4.54 ± 3.03) en el Índice de Dickson. Con los indicadores de calidad de planta se concluye que las progenies del árbol 7 fueron las de mejor calidad con valores mayores de las variables morfológicas.

Cupuaçu tree genotype selection for an agroforestry system environment in the Amazon

Abstract: The objective of this work was to select cupuaçu (Theobroma grandiflorum) tree progenies and individuals based on their agronomic traits, and, indirectly, to identify those adapted to an agroforestry system (AFS) environment in the Brazilian Amazon. For this purpose, 25 full-sib progenies were planted and tested in consortium with black pepper (Piper nigrum), banana (Musa spp.), and bacuri (Platonia insignis) trees. The experiment was carried out in a randomized complete block design, with five replicates and three plants per plot, from 2005 to 2019. For the statistical analyses, the phenotypic averages for production and incidence of witches’ broom disease, evaluated during 11 harvests, were used. Superior progenies and individuals were identified using the mixed model methodology (REML/BLUP), which led to the selection of ten plants from five families with superior agronomic traits. Cupuaçu tree progenies 6, 36, 37, 49, and 52 are the ones that best adapt to the environment of a multispecies AFS in the Amazon region because of their agronomic traits under competitive conditions. Ten matrices show agronomic potential and indirect adaptation to the AFS and can be used as clonal cupuaçu cultivars in this environment.