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Plants respond to infection by accumulating many compounds some of which may function in disease resistance. These include: phytoalexins, antifungal proteins, chitinases, glucanases, esterases, proteaes, phospholipases, lipoxygenases, ribonucleases, peroxidases, phenoloxidases, lignin, callose, hydroxyproline and glycine-rich glycoproteins, phenolic cross-linked polysachcarides, melanin-like pigments, salicylic acid, jasmonic acid, ethylene, peptides, oligosaccharides, hydrogen peroxide and active oxygen species. Though specific avirulence genes, elicitors and elicitor receptors have been reported, the production of defense-related compounds is nonspecific and can be elicited by pathogens, pathogen products and many organics and inorganics. The molecular implications of this specificity/nonspecificity and their significance to disease resistance and practical disease control will be discussed.

The physiological reasons for the differences in sensitivity of C3 and C4 plant species to environmental stresses have not been thoroughly explained. In this study the effects of drought stress on the growth and selected physiological traits were examined in the seedlings of 13 single cross maize (C4 plant) hybrids and 11 spring triticale (C3 plant) breeding lines and varieties differing in drought sensitivity. For plants in the seedling stage the results demonstrated a genetic variation in dry matter accumulation of shoots and roots (DWS, DWR), number (N) and length (L) of particular components (seminal, seminal adventitious, nodal) of the root system, membrane injury by soil drought (LID), osmotic and high temperature stress (LIOS, LIHT), water potential (ψ), water loss (WL), grain germination in osmotic stress (FG, PI), and seedling survival (SS). Seedlings grown under moderate soil drought showed a decrease in dry matter of the top parts and roots and a decrease in the length of seminal, seminal adventitious and nodal roots in comparison to seedlings grown in control conditions. The observed harmful effects of drought stress were more distinct in drought sensitive genotypes. Used in this paper drought susceptibility indexes (DSIGY) were calculated in other experiment by determining the changes in grain yield (GY) under two soil moisture levels (irrigated and drought). The variation of DSIGY for maize ranges from 0.381 to 0.650 and for triticale from 0.354 to 0.578. The correlations between DSIGY and laboratory tests (LI, FG, SS) confirmed that they are good indicators of drought tolerance in plants. The highest values of genetic variation were observed in LI, DWS, SS and WL and the lowest in the measurements of ψ FG, PI, LS, LSA and LN. The correlation coefficients between LIOS and LIHT tests were, in most of the considered cases, statistically significant, which indicates that in maize and triticale the mechanisms of membrane injury caused by simulated drought or high temperature are physiologically similar. It can be concluded that an approach to the breeding of maize and triticale for drought tolerance using these tests can be implemented on the basis of separate selection for each trait or for all of them simultaneously. In that case, it would be necessary to determine the importance of the trait in relation to growth phase, drought timing and level, as well as its associations with morphological traits contributing to drought tolerance. The obtained values of the correlation coefficient between laboratory tests suggest that the same physiological traits may be applied as selection criteria in drought tolerance of maize and triticale genotypes.

Chicory (Cichorium intybus L.; Asteraceae) is a small aromatic and medicinal biennial and perennial herb that is distributed in most parts of Europe and Asia including Iran. However, little information is available about seed germination (SG) and seedling growth of this plant in response to abiotic environmental factors. Therefore, this study aimed to investigate the effect of several environmental factors such as temperature (T), water stress (ψ), salinity, pH and burial depth on SG characteristics of chicory. Results indicated that all studied traits including germination percentage (GP), germination rate (GR), germination uniformity (GU), normal seedling percentage (NSP), root length (RL), shoot length (SL) and seedling dry weight (SDW) are significantly influenced by each environmental factor. Estimated cardinal Ts were 3.5, 28.9 and 40.2 °C for the base, optimum and ceiling T, respectively, with a thermal time 330.2 °C h after fitting a beta model in water. The drought tolerance threshold value was − 0.82 MPa for GP and − 0.75 MPa for NSP. The sensitive of each trait to ψ was ranking RL > SL > GR > SDW > NSP > GP. Increasing salinity level from 0 to 250 mM declined GP, GR, NSP, RL, SL and SDW by 75, 83, 88, 85, 80 and 60%, respectively, and also GU decreased seven times compared with the control. The salt tolerance threshold value was 223 and 194 mM for GP and NSP, respectively. Although chicory seeds were able to germinate at all pH levels (84%, ranged from 2 to 10), they could not produce an equivalent normal seedling in the same condition which indicates that seedling growth is more sensitive to pH relative to SG. The best pH for germination and seedling growth was estimated to be ~ 7 for this plant. Seedling emergence increased by 25% as burial depth increased from 0.5 to 2 cm and then sharply decreased by 87% when reached to 4 cm. The best burial depth ranged from 1 to 2 cm (> 88%) for chicory. Consequently, this information could help us to adequately manage the production of this plant under different environmental factors and also to determine its geographic range expansion in the world.

The combined effects of drought and low light on biomass partition, foliar nitrogen concentration, membrane stability and active oxygen species (AOS) and antioxidant system were investigated in dragon spruce (Picea asperata Mast.) seedlings grown at two watering regimes (well-watered, 100% of field capacity and drought, 30% of field capacity) and light availabilities (HL, 100% of full sunlight and low light, 15% of full sunlight). Under high light condition drought not only reduced foliar nitrogen concentration (Nmass) and membrane stability index (MSI) but also significantly increased biomass partitioning to roots, AOS, ascorbic acid (AsA) content and antioxidant enzyme activities including superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase(GR, EC 1.6.4.2). However, no prominently drought-induced differences in biomass partitioning to root, SOD, GR activities, hydrogen peroxide (H2O2) and MSI were observed in low light seedlings. On the other hand, significant interaction of drought and low light was found on MSI, the antioxidant enzymes activities (SOD, POD, CAT, APX, GR), H2O2 and superoxide radical (O2 −). These results suggested that seedlings grown at the understory were more sensitive to drought than low light.

The chemical composition of hydrodistilled essential oils obtained from aerial parts and roots of selected Caryopteris (‘bluebeard’) species (C. incana, C. mongolica, Caryopteris × clandonensis), as well as the newly established in vitro shoot and adventitious root cultures of the above plants, was analyzed by gas chromatography–mass spectrometry. Essential oil content and composition differed significantly depending on the type of plant material analyzed. Adventitious roots were characterized by the highest essential oil yield, reaching 1.8 % V/DW in Caryopteris × clandonensis. Limonene and cedrol were the main components of the essential oil derived from aerial parts of the intact plants (11.9–16.0 and 10.7–10.9 %, respectively), whereas the volatile fractions of the in vivo roots of all species contained large amounts of 3,5-bis(1,1-dimethyl)-phenol (12.9–26.2 %). 1,8-cineole, absent in the intact plant materials, was the dominating volatile constituent of the essential oils obtained from in vitro shoots (24.8–34.2 %). The volatile oil derived from adventitious root cultures consisted primarily of 1-octen-3-ol (19.7–31.5 %) and medicinally relevant diterpenoids: abietatriene and trans-totarol, which were accumulated in considerable quantities, especially in the adventitious roots of C. clandonensis (21.6 and 29.2 %, respectively).

For centuries in Asia, Rhodiola coccinea has been used as a valuable adaptogen medicinal plant known for its remarkable resistance to various stress factors. Physiological tolerance in chloroplasts is believed to be an important factor, which affects the geographic distribution of plant species. However, there is currently no report on how the physiological tolerance in the chloroplasts of R. coccinea varies along an altitudinal gradient in a semi-arid mountain region. In this work, we investigated the physiological variations of the chloroplasts of R. coccinea plants along an altitudinal gradient in the Tianshan Mountains, which are located in northwest China. It was found that the physiological parameters of chloroplasts in R. coccinea plants, including superoxide generation, fatty acid compositions, thylakoid membrane fluidity, chlorophyll a/b ratios and photosynthetic electron transport rates (ETRs), varied nonlinearly with altitude. Indeed, an inflection point was observed at approximately 3,800 m. For altitudes were higher or lower than 3,800 m, the ETR, index of unsaturated fatty acids in the thylakoid membrane and Chl a/b ratios decreased with increasing altitude, whereas the superoxide generation and DPH polarisation of thylakoid membranes increased. In addition, variations in the AsA and GSH contents of chloroplasts could be divided into two distinct phases along the altitudinal gradient. The AsA content slowly decreased with increasing altitudes up to 3,800 m and rapidly decreased above 3,800 m. However, there was a gradual increase in the GSH content between 3,570 and 3,750 m, followed by an abrupt rise to a plateau level. These results demonstrate that the physiological tolerance of chloroplasts widely varies with altitude and have a tight relationship with the range of growth altitude of R. coccinea in Tianshan Mountains.

Heavy metals (HMs) are among the pollutants posing a significant threat to human, animal, and environmental health. Therefore, monitoring HM concentration changes, especially in the air, is crucial. This study used Corylus colurna L. (Turkish hazelnut) annual tree rings cut in 2020, and it was intended to define the 180-year variations in concentrations of Ni (nickel), Co (cobalt), and Mn (manganese) that are among the most harmful HMs. This study analyzed HMs concentrations in the wood, outer and inner bark in the north, south, east, and west directions and the seasonal variations in HM concentrations in tree rings. It was determined that, for all the three elements, the wood and barks significantly differed (P < 0.001) only in the north side, and the concentrations in wood were much lower than in the bark. The maximum concentrations were usually observed in annual rings in the west and south directions. The changes by both organ and direction can be related to the iron and steel factory and the highway, which are defined as HM sources. The results also revealed that the relocation of Co, Ni, and Mn in the wood of C. colurna tree remained at a limited level. The results suggest that C. colurna annual tree rings are very useful in tracking the variation of Ni, Co, and Mn concentrations.

Gentiana dahurica Fisch is one of four important commercial Radix Gentianae stipulated by the Chinese Pharmacopoeia. We have established a rapid and effective regeneration system using zygotic embryo-derived callus of G.dahurica Fisch. Using this regeneration system, Agrobacteriumtumefaciens-mediated transformation of G. dahurica Fisch has been developed. Zygotic embryo-derived callus was infected with an A.tumefaciens strain (GV3130) harboring a pBI121 vector that contained an nptII selective marker gene. In a total of 60 zygotic embryo-derived calli assayed, frequency of calli with nptII gene PCR-positive transgenic plantlets is 5%. Transient glucuronidase (GUS) expression was observed from these transgenic plantlets. Frequency of GUS-positive transgenic plantlets (4/78) was approximately consistent with that of PCR assay (3/60). Our data indicate that we have successfully established a stable G. dahurica Fisch transformation system by A.tumefaciens. In general, this transformation system we have established might be useful for modifying physiological, medicinal and horticultural traits.