**4. Conclusion**

Beyaz et al. [32] reported that permanent production of antioxidant enzymes and proline in M1 plants of sainfoin (*Onobrychis viciifolia* Scop.) under *in vitro* conditions. In the study conducted by Beyaz et al. [32], the aim was to investigate effects of gamma radiation on physiological responses of the M1 sainfoin plants. Seeds of sainfoin ecotype 'Koçaş' were exposed to 0, 400, 500, and 600 Gy from a 60Co source at a dose rate of 0.483 kGy h−1. Irradiated and unirradiated seeds were sown into culture vessels containing MS-basal medium to be cultured for 30 days under *in vitro* conditions. At the end of this period, seedlings, which germinated from the radiated and unirradiated seeds, were transferred into pots in a growth chamber for 30 days more. Chlorophyll contents, activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR), as well as contents of malondialdehyde (MDA) and proline were examined in unirradiated and irradiated 60-day-old seedlings. Overall, the activities of the antioxidant enzymes (SOD, CAT, and GR) and contents of chlorophyll and proline in the leaves tended to increase after irradiation in a dose-dependent manner. By contrast, the activity of APX decreased. The lipid peroxidation characterized by the MDA content remained unchanged, except after irradiation to 500 Gy. The highest CAT activity and the highest proline content were observed after irradiation to the highest dose of 600 Gy. The highest SOD and GR activities were observed after irradiation to the lowest tested dose of 400 Gy. This is the first study that provided basic information on the impact of gamma radiation on physiological responses of sainfoin and its radiosensitivity. These findings will be useful in development of a mutation breeding program of sainfoin. Also Zaka et al. [33] query the same questions in their investigation and reported that the low chronic ionizing radiation provide genetically transmissible gene expression of antioxidant enzymes such as (SOD, GR, CAT, POD, and GPDH) to the progeny of Spila capillata (Poaceae), which grown two contaminated areas (5.4 and 25 μSv h−1) on the Semipalatinsk nuclear test site in Kazakhstan. They considered evolutionary point of view and answered their observation with the natural populations that can change their genetic structure under environmental constraints and facilitates adaptation. The selective pressure of low radioactive contamination levels (leading to gamma-irradiation dose rates as low as 4.5 and 25 μSv h−1) may have played an important role during 50 years. However, Çelik et al. [25] reported that a high level of ascorbate peroxidase activity (APX) in the leaves generated from irradiated soybean seeds, compared to the unirradiated group. The APX activity increased in the unirradiated group over the experimental period and was increased by 3.6-fold at 14 days and 3.8-fold at 21 days after irradiation (P ≤ 0.05). Kim et al. [34] found that gene expression of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD) can be induced depending on increasing gamma-irradiation dosage level in Triticeae species. Plant cells change their protein metabolism under main stress conditions. Resistant or stress proteins are induced in response to gamma-irradiation stress, and this defense mechanism change patterns of gene expression, especially stress-inducible gene expression, which produces qualitative and quantitative changes in total soluble protein [34, 35]. The different gene expression

40 Plant Engineering

pattern of antioxidant enzymes can be observed in the irradiated plant species [36].

According to Mohammed et al. [37], a substantial variation of the protein patterns of cowpea seeds occur by gamma rays induced, and this variation has occurred because of the new expression of some polypeptide, the silence of others, and overexpression of a third class polypeptides. Aly and El-Beltagi [38] showed that increase in GST, CAT, SOD, and POD It is estimated that the population of the world will be 9.1 billion, which is compared to 34% today, in 2050. Populations of developing countries will be the biggest in this increase. Urbanization will continue at an increasing rate and the majority of the world's population (~70%) will live in urban (compared to 49% today) [49]. However, food production is not increasing parallel to the human population and a large part of the population of today's world is not already well fed. Therefore, humanity has two critical problems such as controlling population growth and increasing food production. It is important for food safety that people are economically and easily accessible to food. For the food security, physical availability and affordability of food are the most important criteria. Induced mutations have a vital role in increasing world food security, because of induced mutations provide new food crop varieties, contributed to the significant increase in crop production and supplied directly accessible of food for the locations people [8]. Mutagenesis has become widespread again in plant breeding during the last decades. Plant mutagenesis, which creates new variation in crop plants, coupled with *in vitro* selection and plant biotechnology methods allows breeders to select for characters that were tough obtain in breeding for only a few decades ago [1]. This is a viable option that increases productivities via "smart" plant varieties that can produce more yield. However, the genetic similarities among crop varieties or unvarying parental materials, which are weaker than the same stress, are limited to uncover new alleles of genes in cropping systems. Therefore, creating new combination of genes causes to break yield plateaux and enhance tolerance. Induced mutation uncovers novel alleles that are used to breed superior crop varieties [50]. The uncovering of new genetic variation in inbred elite cultivars supplies a unique possibility to characterize novel traits, while the lines protect their excellence in the agriculture. Depending on the increasing technology such as whole-genome sequencing and high-resolution analytical techniques, we accumulate more genetic information from a wide range of crop plants and also gain both money and time compared to traditional breeding techniques. However, generated markers in this process offer to the stack of the useful characters, paving the way for developing complex multigenic characters such as abiotic stress resistance [1].

As a results of biotic and abiotic stress factors, the production of reactive oxygen species (ROS) lead to increase in plant cells and cause oxidative stress. Scavenging mechanisms such as antioxidant enzymes keep plants from adverse effect of oxidative stress [30]. If we succeed supplying permanent gene expression of antioxidant enzymes and osmoprotectants such as proline and glycine-betaine by gamma radiation in the plant cell, we can provide tolerances of plants to almost adverse environmental stress factors. For the future, it seems that mutagenic crops continue their important role in plant breeding.
