Systemic Acquired Resistance-Mediated Control of Pine Wilt Disease by Foliar Application With Methyl Salicylate

Pine wilt disease (PWD), caused by the pinewood nematode, is the most destructive disease in pine forest ecosystems worldwide. Extensive research has been done on PWD, but effective disease management is yet to be devised. Generally, plants can resist pathogen attack via a combination of constitutive and inducible defenses. Systemic acquired resistance (SAR) is an inducible defense that occurs by the localized infection of pathogens or treatment with elicitors. To manage PWD by SAR in pine trees, we tested previously known 12 SAR elicitors. Among them, methyl salicylate (MeSA) was found to induce resistance against PWD in Pinus densiflora seedlings. In addition, the foliar applications of the dispersible concentrate-type formulation of MeSA (MeSA 20 DC) and the emulsifiable concentrate-type formulation of MeSA (MeSA 20 EC) resulted in significantly reduced PWD in pine seedlings. In the field test using 10-year-old P. densiflora trees, MeSA 20 DC showed a 60% decrease in the development of PWD. Also, MeSA 20 EC gave the best results when applied at 0.1 mM concentration 2 and 1 weeks before pinewood nematode (PWN) inoculation in pine seedlings. qRT-PCR analysis confirmed that MeSA induced the expression of defense-related genes, indicating that MeSA can inhibit and delay the migration and reproduction of PWN in pine seedlings by modulating gene expression. These results suggest that foliar application of MeSA could reduce PWD incidence by inducing resistance and provide an economically feasible alternative to trunk-injection agents for PWD management.

Influence of rutin-ammonium complex on the physiological condition of pine seedlings

In the plant body, phenolic compounds nonspecifically affect the processes of morphogenesis and perform a wide range of regulatory and protective functions. Of particular interest are the processes involved in the complexation of flavonoids as a result of their interaction with ammonium forms of nitrogen. Polar compounds, which are formed in tissues as a result of chemical transformation, are quite mobile in soil solutions and show high biological activity. The properties of phenol-ammonium complexes are of considerable interest in terms of morphogenesis, physiology of stability, as well as in the system of interaction of plants with soil microorganisms. Studies of the effect of phenol-ammonium complex were performed on seeds and seedlings of Scots pine. Quantitative indicators of germination energy and germination were determined by seed germination. Biochemical profiling of seedling tissue extracts was performed by high-performance thin layer chromatography. It has been experimentally confirmed that rutin (quercetin-3-O-rutinoside) after interaction with 10% aqueous ammonia solution forms a complex of substances, among which the chromatography revealed polar products that potentially affect the regulation of growth. At a total concentration of 15 mg/l, these substances significantly increased germination energy and seed germination. In pine seedlings, they stimulated the growth of roots and shoots. The effect of the complex of organic compounds on seedlings depended on the concentration, duration of seed treatment and had a prolonged effect. The obtained phenol-ammonium complex at a concentration of 10-15 mg/l contributed to an increase in the amount of chlorophylls, carotenoids in the tissues of seedlings, and at 20-40 mg/l increased the content of phenolic synthesis products.

The results of the use of gridless technology for the selection and sowing in a forest nursery of 1000 pieces equalized by weight and size (thickness) of Scotch pine seed fractions

The aim of our research is to analyze the quantitative composition of standard and non-standard Scots pine seedlings grown with all sowing options: calibrated small and large seeds, as well as uncalibrated seeds. As the material for the study, we used a batch of Scots pine seeds, which were divided by weight into two equal parts. Subsequently, one part was calibrated on a sieve-free separator in thickness into small and large fractions, and the second was not calibrated. The size gap in the calibrated fractions was determined experimentally based on the minimum and maximum size of the seed thickness. All the seeds obtained were sown separately from each other in the nursery areas. At the end of the second growing season, using the field method of accounting for the grown planting material, a sample of standard and non-standard seedlings was carried out. As a result, it was found that in crops with calibrated seeds of non-standard seedlings is 25 … 30% less than in crops with non-calibrated seeds. Thus, sowing with Scots pine seeds calibrated in thickness makes it possible to significantly increase the productivity of forest nursery areas in comparison with sowing with uncalibrated seeds.

Co-Infections by Fusarium circinatum and Phytophthora spp. on Pinus radiata: Complex Phenotypic and Molecular Interactions

This study investigated the complex phenotypic and genetic response of Monterey pine (Pinus radiata) seedlings to co-infections by F. circinatum, the causal agent of pine pitch canker disease, and the oomycetes Phytophthora xcambivora and P. parvispora. Monterey pine seedlings were wound-inoculated with each single pathogen and with the combinations F. circinatum/P. xcambivora and F. circinatum/P. parvispora. Initially, seedlings inoculated only with F. circinatum showed less severe symptoms than seedlings co-inoculated or inoculated only with P. xcambivora or P. parvispora. However, 30 days post-inoculation (dpi), all inoculated seedlings, including those inoculated only with F. circinatum, showed severe symptoms with no significant differences among treatments. The transcriptomic profiles of three genes encoding pathogenesis-related proteins, i.e., chitinase (PR3), thaumatin-like protein (PR5), phenylalanine ammonia-lyase (PAL), and the pyruvate decarboxylase (PDC)-encoding gene were analyzed at various time intervals after inoculation. In seedlings inoculated with single pathogens, F. circinatum stimulated the up-regulation of all genes, while between the two oomycetes, only P. xcambivora induced significant up-regulations. In seedlings co-inoculated with F. circinatum and P. xcambivora or P. parvispora none of the genes showed a significant over-expression 4 dpi. In contrast, at 11 dpi, significant up-regulation was observed for PR5 in the combination F. circinatum/P. xcambivora and PDC in the combination F. circinatum/P. parvispora, thus suggesting a possible synergism of multiple infections in triggering this plant defense mechanism.

High Seedling Mortality of Scots Pine Caused by Heterobasidion annosum s.s.

This study provides new information on the infection biology and pathogenicity of an important root-rot fungus, Heterobasidion annosum sensu stricto (Fr.) Bref., through a detailed examination of the vegetative spread of clonal individuals and their capacity to produce fruiting bodies on young pine seedlings. The seedlings were planted in a clear-cutting area (c. 1.2 ha in size) after a pine generation that showed slight external symptoms of Heterobasidion root rot. The first dead seedlings were found five years after planting and during a nine-year monitoring period; nearly 600 seedlings were killed by H. annosum s.s. in 48 individual disease centers. Based on pairing tests of 482 isolates, 117 different H. annosum s.s. genotypes were identified. On average, 2.9 genotypes occurred in a single disease center. The extensive secondary spread of genotypes within root systems (up to 48 pine seedlings infected by the same genotype) resulted in annually expanding disease centers. In addition, more than half of the seedlings killed by H. annosum s.s. produced perennial fruiting bodies thus providing air-borne inoculum. The risk of spore infection should be taken into account in any type of cutting operation in young pine stands. Moreover, new control measures directed towards the secondary spread of H. annosum s.s. in pine regeneration are urgently needed in order to maintain the productivity of the pine forest on infested sites.

The influence of growing medium composition on pine and birch seedling response during the period of simulated spring drought

Climate change increases the earliness and effect of spring dry spells. The efforts to reduce their negative effects on tree regeneration include improvement in physical properties of soil aimed at an increase in water retention and availability. Clinoptilolite from the group of zeolites belongs among such water-absorbent natural materials. The article aims to assess the effect of clinoptilolite admixture in a growing medium, along with different fertilizer concentration, on the growth of pine and birch seedlings and their development during simulated drought. A common (reference) growing medium was tested along with 4 treatments of the growing medium with clinoptilolite. The birch responded to the fertilizer concentration more intensively than to the clinoptilolite admixture and was more vulnerable to drought damage due to a closer dependence of physiological responses on a decrease in the growing medium moisture. The onset of pine withering was slowest in the reference growing medium. A positive effect of clinoptilolite addition on the growth of pine seedlings was confirmed but its unambiguously positive effect on overcoming of spring dry spells was not demonstrated. Clinoptilolite addition with higher fertilizer rate was found as fully unsuitable.

PROCESSING WASTE FROM LOGGING AND WOOD PROCESSING ENTERPRISES INTO A NON-CONVENTIONAL RECLAMATION SUBSTRATE USING ENVIRONMENTALLY FRIENDLY TECHNOLOGY

In Russia, in the field of rapidly and dynamically developing woodworking industry, the issue of recycling waste from logging and woodworking enterprises is becoming relevant. The article reflects information about a new devel-oped technology for processing waste from logging and woodworking enterprises. The developers have proposed an environmentally friendly technology for processing organic waste into a product that has an effective reclamation effect and increases the natural potential of soils. The technology proposed by the authors is based on the unique technical capabilities of the developed installation - a highly efficient mill that grinds down to nano-sized fineness, and a highly efficient mixer that makes it possible to obtain homogeneous mixtures of various materials and different fineness. The unconventional substrate obtained in this way, due to the scientifically grounded composition and ratios of the composite components of organic waste, has effective reclamation properties that increase the soil potential, as well as restoring the fertility of the humus horizon. The use of an unconventional ameliorative substrate in nurseries increased the survival rate and growth rates of Scots pine seedlings both in the open field and in the greenhouse. Thus, the installation proposed by the authors in one technological operation enables the processing of waste from logging and woodworking enterprises and ultimately obtain a product that helps to increase soil potential of degraded lands

Effect of Prunus serotina Ehrh. Volatile Compounds on Germination and Seedling Growth of Pinus sylvestris L.

In temperate European forests invaded by Prunus serotina Ehrh. (black cherry), a reduction in the spontaneous regeneration capacity of Pinus sylvestris L. (Scots pine) is observed. It could be caused by various factors, including allelopathic properties of this invasive plant. In this study the phytotoxic effect of P. serotina volatile compounds on P. sylvestris and the seasonal variation in this effect were assessed. Simple assays showed that volatiles emitted from P. serotina leaves significantly inhibited root growth of P. sylvestris seedlings. Their negative effect on stem growth was much weaker. The strongest phytotoxic effect on Scots pine seedlings was caused by the volatiles emitted from the youngest black cherry leaves. In fresh foliage of P. serotina, nineteen volatile organic compounds were identified by gas chromatography–mass spectrometry (GC–MS). The dominant compound was benzaldehyde. On the basis of tests of linalool alone, it was found that this monoterpene present in the volatile fraction has a strong allelopathic potential and inhibits germination, root elongation and shoot elongation of pine seedlings. The results of our research suggest that volatile compounds from P. serotina leaves could limited survival of P. sylvestris individuals in the seedling phase.