فصلنامه زیست شناسی گیاهی ایران
سال نهم شماره 1 (پیاپی 31، بهار 1396)

This experiment was performed in order to study on ageing mechanisms of chickpea seeds (Cicer arietinum L.) in natural storage and accelerated ageing conditions in seed laboratory of Gorgan Agricultural Science and Natural Resources, Gorgan, Iran at 2015. Experiment was in completely randomized design arrangement with four replications. Treatments were 2 and 4 years natural storage and 1-5 days of accelerated ageing with control treatment. The results showed that with increasing of natural storage and accelerated ageing duration, germination percentage was decreased. Increasing of ageing duration decreased soluble sugars, non-reducing sugars and soluble proteins but lipid peroxidation, reducing sugars, protein carbonylation and Amadori and Millard reaction were increased. In natural storage condition lipid peroxidation was more than sugar hydrolysis but in accelerated ageing condition sugar hydrolysis was more than lipid peroxidation. These results show that the main reason of Amadori and Millard reaction in chickpea seeds in natural storage condition is lipid peroxidation and in accelerated ageing condition is sugar hydrolysis. Also, the results showed that Amadori reaction in natural storage condition was more than Amadori reaction and in accelerated ageing condition Millard reaction was more than Amadori reaction. The results of the present study showed that sever Millard reaction after Amadori reaction induced higher damage on seed and results to more decrease of seed viability and reduce of seed germination percentage in accelerated ageing than natural storage.

Collecting plant specimens and the continuation of this gathering lead to a better understanding of ecosystems, raising awareness about biodiversity and it is criterion for evaluating the genetic erosion over time. Ghalaei-Kashkan covers an area about 30,000 km² and is located in the central Zagros Mountains. Herbarium specimens of the area were collected based on common methods of regional floristic studies during years 1991 to 2013, and named by the Floras of Iran and neighboring countries. In this research, 551 species belonging to 355 genera and 73 families were determined. The chorology of species showed that the highest percentage of the species belonging to the Irano-Turanian region. Permanent Kashkan river caused a strip of the wetland plants have been presented in the northern part of the Ghalaei -Kashkan. Quercus infectoria and Cercis siliquastrum belonging to sub-mountain element that grow in the northern parts. In southern parts of the Ghalaei -Kashkan, particular plant species have been distributed at different altitudes and is divided into Alpine and sub-mountain types. Alpine vegetation type includes mountain Bromegrass, onions (Allium jesdianum), Smyrnium cordifolium, Rheum ribes, and also thorn-cushion vegetations such as: Astragalus spp., Acantholimon spp., Onobrychis spp. and Acanthophyllum spp.. In mountainous type, Oak forests associations are formed. Impact of human on sub-mountain ranges is the main cause of degradation. Genetic erosion in the area implies that the three level of biodiversity: ecosystems, species and populations are under serious threat.

In the present study leaf anatomical and micro morphological characters of 5 species of Geum L. belonging to two subgenera Orthostylus and Geum were studied using light (LM) and scanning electron microscopy (SEM). For anatomical analysis, cross section of basal leaves and their petioles were prepared. The best sections were selected for staining and their photograph were taken. For micro morphological study, leaf and petiole pieces were washed and dried, then prepared for scanning electron microscope. Anatomical and micro morphological characters were carefully examined and measured. The result revealed taxonomically valuable anatomical (glandular hairs, number of epidermal cell around stoma and types of vascular bundle in blade; shape of crust cell, vascular bundle pattern and shape of cross section in petiole) and micro morphological evidences (trichome length, epicuticular was sculpturing, distribution of wax on outer, inner and peristomatal rim and stomata ledge aperture in blade; presence or absence of hairs and their direction, epicuticular was sculpturing types of petiole). These characters are useful for separating the two subgenera and their species. Our findings support the current classifications. An identification key was presented based on the diagnostic studied characters.

High light damages photosynthetic machinery, primarily photosystem II (PSII), and causes photoinhibition that can limit plant photosynthetic activity, growth and productivity. To address this issue, we investigated the basic photoprotection mechanisms including ROS scavenging activity and phenolic compounds production in wheat (Triticum aestivum L.), as a C3 plant, after treatment with low temperature (4°C) and high irradiance (450 and 850 μmol m-2 s-1). Results indicated that wheat plants showed more tolerance to low temperature. Increased tolerance in cold-treated plants was achieved through enhancement in antioxidant system activity. Plants treated with light intensity at 850 μmol m-2 s-1 showed the highest level of stress leading to lower maximal quantum yield of photosystem II (PSII) (Fv/Fm) values. In contrast, the light intensity at 450 μmol m-2 s-1 did not reduce significantly the maximal quantum yield of PSII. This may be attributed to the enhancement of catalase (CAT) activity and anthocyanin synthesis (screening of photoradiation in epidermis cells), and consequently further protection of PSII from photodamage.

Transient gene expression experiments are especially useful to confirm the efficiency of promoters used for expression of foreign molecule in plants. In this study, the expression of the hepatitis B surface antigene (HBsAg) under the control of the CaMV35S and fruit tissue-specific (E8 and 2A11) promoters were studied in the leaf tissues of tobacco and tomato plants and tomato fruits using agroinfilteration technique. The results showed that fruit-specific promoters as the constutative CaMv35S promoter cause over-expression of the antigen in tomato plant fruits. However, HBsAg antigen was expressed in the leaf tissues, but its rate was lower than the fruits. Ethylene produced by the wounded leaf parts may induce fruit-specific promoter, which in turn is related antigen expression. The results show that the tomato fruit specific promoters (E8 and 2A11) can be used as for efficient expression of HBsAg antigen in transgenic tomato plants.

Salinity is one of the most important abiotic stresses that affect plant growth and development. In order to study the effects of salinity stress on oat (Avena sativa L.), salinity treatments including 0 (control), 50, 100, and 150 mM sodium chloride and nitric oxide in form of sodium nitroprusside in three concentrations (0, 25 and 50 µM) were applied. The changes of chlorophyll fluorescence were analyzed using the JIP-test. Results of this experiment showed that concentrations of 50 and 100mM of Nacl did not have a remarkable effects on chloropyll a fluorescence. Significant increase in chlorophyll a fluorescence was observed in highest salinity (150 mM of Nacl). Furthermore, results of this study also revealed that the application of nitric oxide van alleviates the harmful effects of salinity on photosynthetic electron transport chain where application of sodium nitroprusside in concentration of 50 mM, led to decrease in chlorophyll a fluorescence intensity compared to non-treated plant under salinity stress.