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#complementation table

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Gene Dissection and Complementation

In complementation table, (–) indicates

Minus in complementation matrix denotes failure to restore wild-type phenotype indicating persistent mutant trait in trans heterozygote despite diploidy. Both chromosomes carry defective alleles at same locus so no functional gene product available for pathway. Such negative result classifies mutants as allelic belonging to same complementation group and same gene. Consistent scoring requires recessive mutations and controlled conditions where wild-type growth easily distinguished from auxotrophy. Accurate plus/minus assignment underlies construction of cistron map and determination of gene number from mutant collections in formal genetics.

Ref: Pierce, Genetics: A Conceptual Approach, 7th ed., Chapter 8: Interpreting Minus as No Complementation

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Gene Dissection and Complementation

In complementation table, (+) indicates

Standard complementation tables score growth or phenotype of trans heterozygote using plus symbol to indicate appearance of wild-type trait meaning successful complementation and functional restoration. Plus signifies both parental genomes together provide functional products compensating recessive defects restoring enzymatic flux or structural function. Mutations producing plus when paired belong to different complementation groups and different genes. Convention originates from microbial auxotroph studies where plus denotes growth on minimal medium and minus denotes failure now extended to Drosophila cis-trans tests and somatic hybrids.

Ref: Griffiths et al., Introduction to Genetic Analysis, 12th ed., Chapter 7: Scoring Complementation Plus Means Wild Type

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