Cutinsomes of Malus Mill. (Rosaceae) leaf and pericarp: genesis, localization, and transport.

New data were obtained on specific bionanostructures, cutinsomes, which are involved in the formation of cuticles on the surface of leaf blades and pericarp of Malus domestica Borkh (Malus Mill., Rosaceae)introduced to the mountains at the altitudes of 1200 and 1700 m above sea level. Cutinsomes, which are electron-dense structures of spherical shape, have been identified by transmission electron microscopy. It was demonstrated that plastids can be involved in the synthesis of their constituent nanocomponents. The greatest number of nanoparticles was observed in the granal thylakoid lumen of the chloroplasts in palisade mesophyll cells and pericarp hypodermal cells. The transmembrane transport of cutinsomes into the cell wall cuticle proper by exocytosis has been visualized for the first time. The plasma membrane is directly involved in the excretion of nanostructures from the cell. Nanoparticles of cutinsomes in the form of necklace-like formations line up in a chain near cell walls, merge into larger conglomerates and are loaded into plasmalemma invaginations, and then, in membrane packing, they move into the cuticle, which covers both outer and inner cell walls of external tissues. The original materials obtained by us supplement the ideas about the non-enzymatic synthesis of cuticle components available in the literature and expand the cell compartment geography involved in this process.

Investigating the Physiological and Molecular Responses of Solanum lycopersicum hp Mutants to Light of Different Quality for Biotechnological Applications.

The effect of the light of different spectral compositions, white fluorescent light (WFL), red light (RL, 660 nm), blue light (BL, 450 nm), green light (GL, 525 nm), and white LED light (WL, 450 + 580 nm), on the physiological parameters of Solanum lycopersicum 3005 hp-2 (defective for a DET1 gene) and 4012 hp-1w; 3538 hp-1; 0279 hp-1.2 (defective for a DDB1a gene) photomorphogenetic mutants was studied. The parameters of the primary photochemical processes of photosynthesis, photosynthetic and transpiration rates, the antioxidant capacity of low-molecular weight antioxidants, the content of the total phenolic compounds, including flavonoids, and the expression of the genes involved in light signaling and biosynthesis of secondary metabolites were determined. Under BL, the 3005 hp-2 mutant showed the highest nonenzymatic antioxidant activity, which occurred to a greater extent due to the increase in flavonoid content. At the same time, under BL, the number of secretory trichomes on the surface of the leaves of all mutants increased equally. This suggests the accumulation of flavonoids inside leaf cells rather than in trichomes on the leaf surface. The data obtained indicate the possibility of using the hp-2 mutant for biotechnology to increase its nutritional value by enhancing the content of flavonoids and other antioxidants by modulating the spectral composition of light.

Micromorphology of the leaf surface in some species of Dryadoideae (Rosaceae).

The leaf surface of 5 species of the subfamily Dryadoideae (Rosaceae) was studied for the first time by cryoscanning electron microscopy. In the studied representatives of Dryadoideae, some signs of micromorphology were found that are characteristic of other Rosaceae. In Dryas drummondii and D. x suendermannii, cuticular folding was found on the cell surface of the adaxial leaf side. Stomatal dimorphism was found in Cercocarpus betuloides. A representative of the genus Cercocarpus had pronounced differences from the species of the genus Dryas in less pubescence of the abaxial surface with shorter and thicker trichomes, in small elongated stomata, and in smaller cells of the adaxial epidermis. Glandular trichomes and long multicellular outgrowths (possibly emergences) were found on veins in D. grandis. Structures resembling hydathodes or nectaries have also been noted on the leaf margin in this species.

Effect of Phytochrome Deficiency on Photosynthesis, Light-Related Genes Expression and Flavonoid Accumulation in Solanum lycopersicum under Red and Blue Light.

The effect of red (RL, 660 nm) and blue (BL, 450 nm) light on phy mutant tomato plants was studied. The rates of photosynthesis (Pn) and transpiration, the efficiency of the primary photochemical processes of photosynthesis, the contents of flavonoids and phenolic compounds, the low-molecular-weight antioxidant capacity (Trolox equivalent antioxidant capacity (TEAC)) of leaf extracts, and the expression of light-dependent genes were evaluated. Under RL, BL, and white fluorescent light (WFL), the Pn values decreased in the order: WT > phyb2 > phyaphyb2 > phyaphyb1phyb2, except for the Pn in phyb2 on BL. Phyb2 also had a larger number of stomata under BL and, as a result, it reached maximum transpiration. The noticeable accumulation of flavonoids and phenolic compounds was observed only in the phyb2 and phyaphyb2 mutants upon irradiation with BL, which agrees with the increased TEAC in the leaf extracts. We suggest that the increased antioxidant activity under PHYB2 deficiency and the maintenance of high photosynthesis under BL are based on an increase in the expression of the early signaling transcription factors genes BBX, HY5. The largest decrease in the content of flavonoids and TEAC was manifested with a deficiency in PHYB1, which is probably the key to maintaining the antioxidant status in BL plants.

Outer and internal cuticle in the leaves of Malus (Rosaceae) in mountains and plains.

The outer and internal cuticles in apple (Malus domestica Borkh.) leaves on the plain and in the mountains was studied using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). The outer cuticle consisted of lamellate and homogeneous layers of the cuticle proper and cuticular layer containing electron-transparent plates and electron-dense dendrites. Blue fluorescence predominated in the cell wall. The cuticle fluoresced green and red. The intensity of the red part of the spectrum in the cuticle increased with altitude, and the number of electron-transparent plates increased within the cuticular layer. The cell wall on both leaf sides was the thinnest in the arid conditions (300 m). At an altitude of 600 m, under favorable temperature and rainfall conditions, the cuticle thickness increased due to the cuticular layer adjacent to the cell wall. The internal cuticle was distinguished by intense yellow or red autofluorescence, similar in color and spectrum to the outer cuticle. The outer and internal cuticles had cuticular folds. The average distance between the ridges of the internal cuticle was almost the same in the samples at different altitudes. The ridge height was maximum at 600 m. RESEARCH HIGHLIGHTS: The altitudinal effects on outer and internal cuticles in apple leaves were studied. In the forest-mountain zone, the cuticle thickness increased due to the cuticular layer adjacent to the cell wall. The cell wall was the thinnest in arid conditions.

The features of the fatty acid composition of Pyrus L. total lipids are determined by mountain ecosystem conditions.

The composition of fatty acids (FAs) of total lipids of pericarp, seeds, and leaves of Pyrus caucasica Fed. and Pyrus communis L. growing in mountain ecosystems at different altitudes (300, 700 and 1200 m) was studied. It was found that the greatest differences in the relative content of FAs within a species, depending on the altitudes above sea level, were characteristic of the outer tissues of the pericarp (peel) and leaves, which were in direct contact with the external environment. Pericarp parenchyma to a lesser extent, and seeds practically did not differ in FA composition at different heights. At altitudes with increased UV radiation, conjugated octadecadienoates: rumenic acid (9,11-18:2) and 10,12-18:2 were registered in the pericarp and leaf of Purys L., the functions of which in plants were practically not studied. The wild P. caucasica at all growing altitudes was characterized by more very-long-chain FAs (VLCFAs) than the P. communis cultivar. At 700 m, most likely when exposed to fungal infections, the relative number of VLCFAs increased significantly, and new species of individual odd-chaine FAs appeared in their composition in both representatives. It was especially worth noting the appearance in peel and leaf melissic acid (30:0), which was rarely recorded in the plant. A characteristic feature of only P. communis at an altitude of 700 m was the large number of unsaturated individual VLCFAs. Based on the data obtained, a scheme of possible pathways for VLCFA biosynthesis in P. communis were proposed.

Polyunsaturated and Very-Long-Chain Fatty Acids Are Involved in the Adaptation of Maloideae (Rosaceae) to Combined Stress in the Mountains.

One of the mechanisms of plant adaptation to combined stress under conditions of altitudinal zonation is changing the lipid fatty acid (FA) composition. The main changes in the FA composition occurred in the outer cell layers of the pericarp, but not in the parenchyma. Adaptation was found to be species-specific. In Cydonia oblonga Mill. and Malus domestica Borkh., the ratio of polyunsaturated 18:2 and 18:3 lipid FAs changed with increasing height, while a constitutive level of the unsaturation index (UI) and low contents of very-long-chain fatty acids (VLCFAs) were maintained. Mespilus germanica L. was characterized by a higher level of VLCFAs due to the high content of 20:0. The sum of VLCFAs in medlar increased by up to 16 % with changing altitude, which was accompanied by the changes in the ultrastructure of chloroplasts and a noticeable decrease in the UI. We attribute the differences in the adaptive strategies in C. oblonga, M. domestica and M. germanica to specific structural features of the pericarp peel. Despite different adaptation mechanisms, the studied species can grow equally successfully at the altitudes from 300 to 1200 m.