Necessary for the hydroxylation of but-3-enyl glucosinolate to 2-hydroxybut-3-enyl glucosinolate, which is toxic to insects, bacteria and nematodes, inhibits seed germination and produces bitter flavors. AH2 + gluconapin + O2 = A + H2O + progoitrin Binds 1 Fe(2+) ion per subunit. Expressed in leaves and seeds. All cultivars with seed-only-functional allele have low to non-detectable GSL-OH expression in the leaves. Cv. Adb-0, cv. Ag-0, cv. Ang-0, cv. Bla-10, cv. Bs-1, cv. Bur-0, cv. Cal-0, cv. Cnt-1, cv. Columbia, cv. Di-1, cv. Edi-0, cv. Ei-2, cv. Ema-1, cv. Et-0, cv. Ge-0, cv. Lc-0, cv. Lo-2, cv. Mir-0, cv. Mrk-0, cv. Mt-0, cv. Pog-0, cv. Rd-0, cv. Rou-0, cv. Sf-1, cv. Tac-0, cv. Wei-0 and cv. Yo-0 contain a leaf- and seed-functional allele. Cv. Di-0, cv. Kas-1, cv. Lip-0, cv. Landsberg erecta, cv. Sha, cv. Sorbo, cv. Tsu-1 and cv. Wassilewskija contain a seed-only-functional allele. Cv. Cvi-0, cv. Hodja-Obi-Garm and cv. Kon contain a null allele. The null allele in cv. Cvi-0 is produced by 5 amino acid substitutions while the one in cv. Kon or cv. Hodja-Obi-Garm is produced by a substitution generating a stop codon at position 132. Plants exhibit a complete absence of 2-hydroxybut-3-enyl glucosinolate accumulation and a decreased resistance to generalist herbivory. Belongs to the iron/ascorbate-dependent oxidoreductase family. Truncated N-terminus.