This study was conducted to evaluate the effects of the prepared ointments from Mentha piperita essential oil (M. piperita) on wound healing in the infected mice models. Each circular full-thickness wound was inoculated with 25 × 10 units of Staphylococcus aureus and Pseudomonas aeruginosa bacteria strains. The tissue bacterial count, histological analyses and expression levels of IL-10, TNF-α, TGF-β1, IL-1β, CCL2, CXCL1, VEGF and FGF-2 were assessed to identify the different doses of M. piperita on wound healing. Total tissue bacterial count, edema and inflammation level were declined, but the migration of fibroblasts, collagen synthesis and re-epithelization were increased in treated animals with M. piperita. The expression levels of CCL2, CXCL1, IL-1β, TGF-β1 and IL-10 genes were up-regulated in the M. piperita-treated animals compared to the control group. While the expression of TNF-α, VEGF and FGF-2 was down-regulated in comparison to the control group. This study indicated that M. piperita can be used for treatment of the infected wound.

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The chamazulene and α-(−)-bisabolol contents and quality of the chamomile oil are affected by genetic background and environmental conditions. Salicylic acid (SA), as a signaling molecule, plays a significant role in the plant physiological processes. The aim of this study was to evaluate the chemical profile, quantity, and improve the essential oil quality as a consequence of the increase of chamazulene and α-(−)-bisabol using salicylic acid under normal and heat stress conditions by the gas chromatography-mass spectrometry (GC-MS) technique. The factorial experiments were carried out during the 2011–2012 hot season using a randomized complete block design with three replications. The factors include four salicylic acid concentrations (0 (control), 10, 25 and 100 mg·L−1), and three chamomile cultivars (Bushehr, Bona, Bodegold) were sown on two different planting dates under field conditions. Fourteen compounds were identified from the extracted oil of the samples treated with salicylic acid under normal and heat stress conditions. The major identified oil compositions from chamomile cultivars treated with salicylic acid were chamazulene, α-(−)-bisabolol, bisabolone oxide, β-farnesene, en-yn-dicycloether, and bisabolol oxide A and B. Analysis of variance showed that the simple effects (environmental conditions, cultivar and salicylic acid) and their interaction were significant on all identified compounds, but the environmental conditions had no significant effect on bisabolol oxide A. The greatest amount of chamazulene obtained was 6.66% at the concentration of 10 mg·L−1 SA for the Bona cultivar under heat stress conditions, whereas the highest α-(−)-bisabolol amount attained was 3.41% at the concentration of 100 mg·L−1 SA for the Bona cultivar under normal conditions. The results demonstrated that the application of exogenous salicylic acid increases the quantity and essential oil quality as a consequence of the increase of chamazulene and α-(−)-bisabolol under normal and heat stress conditions.

SummaryTo study the effects of high temperature on the meiosis of pollen mother cells (PMCs) and to determine their relationship with grain set, two in situ experiments were conducted between 2010 and 2012 on four wheat cultivars, Kauz, Montana, M6 and Chamran, under normal (normal cultivation) and terminal heat stress (late cultivation) conditions. Due to the delay in cultivation for the cultivars under stress conditions, their flowering stage faced heat stress at the end of the growing season, and therefore, a significant (p ≤ 0.05) increase was observed in meiotic abnormalities. Cytogenetic studies discovered that the meiosis in PMCs and the pollen development are strongly influenced by heat. Based on the results, abnormalities such as precocious chromosome migration to the poles, laggard chromosomes, micronuclei, absence of metaphase plate, pyknosis, abnormal cytokines, cytomixis and abnormal tetrad were observed in different cultivars. The sensitive cultivars, M6 and Montana, had the greatest percentages of meiotic abnormalities. The meiotic abnormalities showed a significant negative correlation with the number of kernels per spike under terminal heat stress conditions (r = 0.54, n =16, p ≤ 0.01). In other words, due to increasing meiosis abnormalities under terminal heat stress, the grain set was greatly reduced, especially in the susceptible cultivars. The result of this experiment showed that studying the meiosis in PMCs can be suggested as one of the research necessary to improve commercial heat-tolerant cultivars, and to some extent, as a method for screening tolerant lines in breeding programs.

Abstract:The objective of this study was to investigate the effect of exogenous application of salicylic acid concentrations on the physiological and biochemical traits and essential oil content of chamomile under normal and heat stress conditions as induced by delayed sowing. The experiments were conducted during 2011-2012 as a factorial using a randomized complete block design with three replications, in a very hot region. The factors included five salicylic acid concentrations (0 (control), 1, 10, 25 and 100 mg¨L´1) and three chamomile cultivars (Bushehr, Bona, Bodegold). The seeds of chamomile were sown on two different sowing dates including an optimum planting date and a late planting date. The physiological traits (plant height, capitol diameter, 1000 grain weight, fresh and dried flower weight), total chlorophyll, proline and essential oil content were investigated. Analysis of variance showed that the effect of the environmental conditions (normal and heat stress) was significant on all physiological and biochemical traits with the exception of the essential oil content. The heat stress decreased physiological traits and total chlorophyll in comparison with the normal conditions but it had no significant effect on the essential oil content. Findings indicated that the application of exogenous salicylic acid improves essential oil content in chamomile cultivars under environmental heat stress conditions.