Abstract
Greenhouse experiment is carried out to explore the outcome of γ-radiation on physiological and genetic variation in red radish (Raphanus sativus) for two generations. Gamma rays from 60Co were used to penetrate red radish seeds with different dose levels (0.0, 10, 20, 40 and 80 Gy). Plants generated from irradiated seeds and from self-pollination of these plants, called M1 and M2 generations, respectively. Some morphological and physiological traits were then determined, and the genetic diversity of both generations was studied using Start Codon Targeted (SCoT) and Conserved DNA-Derived Polymorphism (CDDP) molecular markers. All studied morphological traits (number of leaves/plants, leave height, root diameter, and root weight) were steadily improved by raising irradiation dose rate, reaching a cumulative raise at the irradiation doe level 40 Gy and decreased at dose level 80 Gy. Photosynthetic pigments of red radish plants released a notable increase by increasing gamma rays dose level for chlorophyll (a), chlorophyll (b) and carotenoids for 40 Gy dose rate. Proline content was elevated proportionally to the irradiation dose level, with the greatest increase seen at dose level of 80 Gy. Moreover, phytochemical screening was detected for the both two generations. Fourteen SCoT primers generated a total number of banding patterns of 194 with average 13.86 and the primer SCoT-33 released the highest number banding patterns (21). The percentage mean of polymorphism for all the SCoT primers was 74.66% and was 66.49 and 63.74% for M1 and M2 respectively. Furthermore, fifteen CDDP primers generated a total number of banding patterns of 186 and the primer CDDP-5 relieved the highest number of banding patterns (20). The percentage mean of polymorphism for all the CDDP primers was 73.41% and was 64.38 and 65.91% for M1 and M2 respectively. It could be concluded that gamma irradiation exhibited an appropriate variation in red radish M1 and M2 which was detected by SCoT and CDDP molecular markers.
Highlights
Radish (Raphanus sativus) is a root vegetable that belongs to the family Brassicacea (Cruciferae), and it’s cultivated and consumed worldwide and considered to be part of the human diet even though it’s not widespread in certain cultures
The use of Start Codon Targeted (SCoT) and Conserved DNA-Derived Polymorphism (CDDP) markers for studying genetic diversity are reported here for the first time for irradiated red radish. This confirms that the combined data of SCoT and CDDP techniques were suitable for evaluating the genetic relationships among the red radish two generations because they accurate the information about genetic diversity
Some past studies made on the effects of γ-radiation in plants reported that gamma irradiation can cause variations in vegetative characteristics, flowering development, rhizome traits, as well as in maturity in both a negative or positive manner, depending on the applied dose and the radio-sensitivity of the plant being irradiated, where at low doses the plant shows a progression in growth while at high doses of radiation the opposite is seen (Taheri et al, 2014; Ambavane et al, 2015; Aly et al, 2019a)
Summary
Radish (Raphanus sativus) is a root vegetable that belongs to the family Brassicacea (Cruciferae), and it’s cultivated and consumed worldwide and considered to be part of the human diet even though it’s not widespread in certain cultures. Plant breeding uses many approaches, among them are induced mutagenesis to create new plant variants This method is seen as a fast, low-cost, and reproducible technique to speed up the process of generating and viewing crop genotypes with recovered genomics (FAO/IAEA 2017). The CDDP method for generating plants DNA markers based on the information mined for small conserved amino acid sequences present in plant proteins (Mokhtar and Atia, 2019) Such gene-targeted techniques via the use of a gene or promoter in their primers, SCoT and CDDP were created to merge the achievement of marker procedures with modern practical originality, give greater replication and declaration, by the instantaneous happening of dominant and codominant markers (Abouseadaa et al, 2020). As well as some physiological and phytochemical characteristics were determined to understand the irradiation effects on plant biochemistry characteristics were concerned
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