The multiple-cluster mutation complex in mutagenesis with higher plants

Area of Science:

• Plant genetics
• Mutation breeding
• Agricultural science

Background:

• Understanding mutation induction is crucial for crop improvement.
• Barley (Hordeum vulgare) is a vital cereal crop.
• Mutagenesis research explores genetic variation for breeding.

Purpose of the Study:

• To investigate the effects of different mutagens (gamma-rays, EMS, NEU, EI) on mutation types in barley.
• To evaluate the impact of seed pre-soaking on mutation frequency and types.
• To characterize new and existing mutation types in barley.

Main Methods:

• Barley seeds (dry and pre-soaked) were treated with gamma-rays, ethyl methanesulfonate (EMS), N-ethyl-N-nitrosourea (NEU), and ethylenimine (EI).
• Mutation frequencies (total, cluster, multiple) were analyzed in M1 and M2 generations.
• Chimera size was assessed based on segregation ratios of seedling mutations.

Main Results:

• EMS and NEU treatments resulted in higher frequencies of multiple mutations.
• Gamma rays and NEU treatments led to a greater number of cluster mutations.
• Pre-soaking seeds reduced the frequency of total, cluster, and multiple mutations.
• Mutation frequency was independent of mutagen type and treatment stage for specific seedling mutations.
• Chimera size varied among mutation types, with largest sizes in albina and eceriferum, and smallest in viridis.

Conclusions:

• Mutagen type and seed hydration influence mutation induction and types in barley.
• Seed pre-soaking generally reduces mutation frequency, possibly due to lower effective doses or later developmental stage of mutation.
• Observed variations in chimera size may relate to premutation stability, dominant mutations, or lethal interactions.