Difficulty: Easy
Correct Answer: All of these
Explanation:
Introduction / Context:Nematodes severely impact crop yields. Resistance can be introduced by several non-transgenic strategies: wide hybridization aided by embryo rescue, induced mutation breeding, and conventional selection including somaclonal variants from tissue culture.
Given Data / Assumptions:
Concept / Approach:Embryo rescue salvages hybrids from wide crosses that might otherwise abort, transferring resistance from wild relatives. Mutation breeding creates new alleles that may confer resistance. Non-recombinant DNA methods include recurrent selection, marker-assisted backcrossing if markers are available, and exploiting somaclonal variation.
Step-by-Step Solution:
Use embryo rescue to introgress resistance from wild species.Apply mutagens (physical/chemical) to generate diversity; screen progeny for resistance.Leverage non-transgenic selection pipelines to fix and stack favorable alleles.Verification / Alternative check:Greenhouse and field nematode inoculation tests validate resistance; molecular markers can track introgressed segments.
Why Other Options Are Wrong:
Common Pitfalls:Failing to pyramid resistance sources; relying on a single mechanism can lead to breakdown under field pressure.
Final Answer:All of these
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