When working on barley plants, two researchers independently identify a short-plant mutation and develop homozygous recessive lines of short plants. Careful measurements of the height of mutant short plants versus normal tall plants indicate that the two mutant lines have the same height. How would you determine if these two mutant lines carry mutation of the same gene or of different genes?

Key Concepts

Homozygosity and Recessive Traits

Homozygosity refers to having two identical alleles for a particular gene, which can be either dominant or recessive. In this context, the short-plant mutation is recessive, meaning that the phenotype (short height) is expressed only when both alleles are recessive. Understanding homozygosity is crucial for determining the genetic basis of the observed traits in the barley plants.

Genetic Complementation Test

A genetic complementation test is used to determine whether two mutations that produce similar phenotypes are in the same gene or in different genes. By crossing the two mutant lines and observing the phenotype of the offspring, researchers can infer whether the mutations complement each other (indicating different genes) or fail to complement (indicating the same gene). This test is a fundamental method in genetics for analyzing gene function.

Phenotypic Analysis

Phenotypic analysis involves studying the observable characteristics of organisms, such as height in barley plants. By comparing the phenotypes of the mutant lines and their offspring, researchers can gather evidence about the genetic basis of the traits. This analysis is essential for understanding how mutations affect plant characteristics and for drawing conclusions about the underlying genetic mechanisms.