The first gene involved in the biosynthesis of xylan was revealed on xylem mutants (irx) in Arabidopsis thaliana because of some mutation affecting xylan biosynthesis genes. As a result, abnormal plant growth due to thinning and weakening of secondary xylem cell walls was seen. Arabidopsis mutant irx9 (At2g37090), irx14 (At4g36890), irx10/gut2 (At1g27440), irx10-L/gut1 (At5g61840) showed defect in xylan backbone biosynthesis.
The initial gene involved in xylan biosynthesis was discovered on xylem mutants (irx) in Arabidopsis thaliana due to a mutation affecting genes related to xylan synthesis. This led to abnormal plant growth resulting from weakened secondary xylem cell walls, characterized by thinning and weakening.