Induction of new clones of Egyptian garlic (Allium sativum cv. Elbalady) by using chemical mutagens and somatic embryogenesis

Abstract

The present study aims to induce new clones of Egyptian garlic cv. Elbalady by using chemical mutagenesis and somatic embryogenesis and determine the genetic diversity in these clones.

The field treatments of our study was carried out, in Kaha vegetable research farm, Qalyubia governorate, Egypt on garlic, to investigate the influence of chemical mutagens type (ethyl methane sulfonate, sodium azide and colchicine), soaking periods (6 and 12 h) and concentrations (0.01, 0.05 and 0.1%) on vegetative growth and yield characteristics. The results showed that sodium azide at concentration 0.01% achieved the lowest vegetative growth and yield characteristics values at first and second seasons but increased in the third season, while the concentrations 0.05 and 0.1% led to non-germinated cloves confirming that they are lethal doses. Ethyl methane sulfonate and colchicine had positive effects on vegetative growth and yield characteristics. Five new clones were obtained from these treatments, and the clones were evaluated as well as control during the years following to confirm the stability of the new traits.

The in vitro part of our study was performed in Tissue Culture Research Laboratory, Vegetable Research Departments, Horticulture Research Institute, Giza, Egypt to induce genetic variation through somatic embryogenesis of garlic cv. El Balady. Root tips cultured on MS medium supplemented with various concentrations of 2,4-D ( 0, 1, 2, 3, and 4 mg/l) to callus formate. The formed callus subcultured into MS medium supplemented with a combination of 2,4-D and BA at concentrations (0, 1 and 2 mg/l) for callus differentiation. The results show that 2,4- D at concentration 1 mg/l gave the highest callus formation traits and BA obtained the highest callus differentiation traits. Obtained embryos subcultured into fresh medium to produce micro bulbs. Four new clones were obtained from in vitro which adapted and cultivated in the greenhouse for evaluation.

By using two dominant molecular marker techniques Start Codon Targeted (SCoT) polymorphism and sequence-related amplified polymorphism (SRAP) to find the genetic distance among the nine different treated clones in comparison with the untreated one which is used as a control.

 Two sets of ten SCoT primers and ten SRAP primers were deployed to examine the genetic variation among the new clones compared with control. Out of 88 amplified fragments were scored by using SCoT marker, a total of 34 polymorphic fragments were detected at molecular size ranging from 100 to 3500 bp. Out of 78 amplified fragments were scored by using SRAP marker, a total of 42 polymorphic fragments were detected at molecular size ranging from 100 to 4000 bp. The genetic similarity percentages of genomic DNA using SCoT marker ranged from 89% to 57%. While, the genetic similarity percentages of genomic DNA using SRAP marker ranged from 95% to 45%. These results revealed 92% genetic similarity between clones 8 and 10 and 68% between clones 4 and10. They were clustered into two major groups based on the UPGMA analysis where, the clone 4 was the most related clone to the first cluster as agronomic trait and the second cluster as somatic embryogenesis trait. So, the current study increased the genetic diversity base of garlic somatic embryogenesis and mutagenesis.