No abstract

In plant breeding programs, one of the oldest methods is mutation breeding. Currently, mutation breeding has became popular among the breeders and scientists again with its use in plant biotechnology and due to some restrictions on the other techniques such as hybridization, cross breeding, and transgenic plants. Physical mutagens (X-rays, UV light, neutrons-alpha-beta particles, fast and thermal neutrons, especially gamma rays) are used more widely than chemical (ethyl methanesulfonate [EMS]) ones to artificially induce mutations (mutagenesis). However, among the physical mutagens, gamma-rays are widely used. During the irradiation of the seeds with ionizing radiation to generate mutants with desirable traits, reactive oxygen species (ROS) or free radicals can generate in cells. Although, these radicals/species generally can be very dangerous for the cell compartments, they can take an important role as a signal molecule activation of genes of antioxidant enzymes and proline, which are defense systems against these radicals in plant cells. In this chapter, usability of gamma-irradiation to provide the permanent gene expression of antioxidant enzymes and proline through the production of reactive oxygen species (ROS) is discussed.

Salt stress is one of the harmful abiotic stress factors. It makes agricultural lands especially in arid and semi-arid regions useless despite the efforts. More than six percent of total world agricultural lands are on the edge of vanishing due to salt stress. Salinity in soil occurs as a result of the factors such as lack of drainage, improper irrigation, excessive accumulation of soluble salts. Salinity limits the growth of plants. Despite the main results, some results of plants due to these limitations vary from species to species. The negative effects get morphological, biochemical and physiological reactions from plants. Slowed or stopped growth of roots and shoots, closuring of stomata, germination slowing, decreased or stopped development of seedling, deterioration of photosynthetic activity are the main reactions of plants to stress. On the other hand, plants also develop tolerance mechanisms as a result of some auxiliaries for surviving under adverse conditions. Plants have tendency to protect themselves from salinity with osmotic protectants synthesized by them such as sugars, proline, amino acids, glycine betaine. In this review, the responses of plants to salt stress were investigated and gathered.

The aim of this study was to compare seed germination percentage, seedling growth, total chlorophyll and protein content, sugar content, and root and sugar yields of sugar beet (Beta vulgaris L.) genotypes at different ploidy levels. Sugar beet seeds from cultivars "Agnessa" and "Felicita" (diploids), and lines "AD 440" and "CBM 315" (tetraploids) were obtained from the Sugar Research Institute, Etimesgut, Ankara. Seed germination percentage was recorded after 4 days, whereas seedling and root lengths were noted 4 and 14 days after the study initiation. The size of epidermal cells in length and width were determined on the upper leaf surface of 6-week-old plants. Six and 10 weeks after seed sowing, plant and root lengths, leaf length and width, plant fresh and dry weights, and total chlorophyll and protein content were measured. Data related to yield components such as sugar content, root and sugar yields were obtained from trials conducted by the Sugar Research Institute under field conditions 6 months after study initiation. In the current study, diploid genotypes showed superior responses regarding generative characteristics while tetraploids passed diploid ones vegetatively in the further stages of the development. Ten weeks after study initiation, the highest results regarding vegetative characters such as plant height, root and leaf lengths, leaf width, approximate leaf area, plant fresh and dry weights, and tissue water content were recorded from tetraploid genotypes as 35.00 cm, 43.85 cm, 18.40 cm, 9.25 , respectively.

This study was conducted to evaluate the effect of different NaCl concentrations (0, 100 and 150 mM) on the morphological and biochemical parameters of different sainfoin ecotypes ‘Koçaº’, ‘Malya,’ ‘Altýnova’ and ‘Ulaþ’ under controlled conditions. The morphological parameters included seed germination, seedling and root lengths, and seedling fresh and dry weights while the biochemical parameters included chlorophyll and proline contents, lipid peroxidation (MDA), and the activities of antioxidant enzymes (SOD, CAT, APX, and GR). The results demonstrated that increase in NaCl concentration caused an overall decrease in morphological parameters and an increase in the biochemical parameters in all ecotypes. The findings showed that among all ecotypes, ‘Koçaþ’ had higher chlorophyll and proline content, increased activity of CAT, GR, and APX, and increased fresh and dry weight in response to salt stress. To the best of our knowledge, this is the first report on the evaluation of enzymatic and non-enzymatic defense systems in sainfoin plants under salt stress.

This study was conducted to investigate the biochemical responses of the shoot and root tissues of sainfoin to drought stress under in vitro conditions. Seeds of sainfoin were cultured on MS (Murashige and Skoog) medium with addition of concentrations of PEG-6000 (50, 100, and 150 g/l). Biochemical analyzes (CAT, SOD, GR, and APX enzyme activity; proline, malondialdehyde (MDA) and chlorophyll contents) were carried out on the 35-day-old seedlings. The principal results of the study were that CAT and SOD antioxidant enzymes seemed to play a critical role in oxidative stress in both tissues of sainfoin seedlings. On the other hand, a significant decrease in GR activity and no change in APX activity detected in both tissues under stress. The contents of proline and MDA increased in both tissues while the chlorophyll contents decreased in the shoot tissue. Antioxidant enzyme activities seemed to be more active in the root tissue than the shoot tissue. Accumulation of proline was higher in the root tissue, while the MDA content was higher in the shoot tissue of the seedlings.

No abstract

Dormancy is when there is a lack of germination in seeds or tubers even though the required conditions (temperature, humidity, oxygen, and light) are provided. Dormancy is based on hard seed coat impermeability or the lack of supply and activity of enzymes (internal dormancy) necessary for germination. Dormancy is an important factor limiting production in many ield crops. Several physical and chemical pretreatments are applied to the organic material (seeds/tubers) to overcome dormancy. Physical and physiological dormancy can be found together in some plants, and this makes it diicult to provide high-frequency, healthy seedling growth, since the formation of healthy seedlings from the organic material (seeds/tubers) sown is a prerequisite for plant production. This chapter will focus on the description of four diferent methods we have not seen reported elsewhere for overcoming dormancy.