Ea. Barlaan et al., Molecular mapping of the cnx2 locus involved in molybdenum cofactor biosynthesis in rice (Oryza sativa L.), THEOR A GEN, 102(4), 2001, pp. 540-544
Molybdenum cofactor (Moco) is essential for nitrate reductase (NR), xanthin
e dehydrogenase (XDH), and aldehyde oxidase to perform their catalytic func
tions in plants. Moco biosynthesis is a complex process involving many gene
s. Little is known about the genetics and molecular aspects of Moco biosynt
hesis in plants and other eukaryotes. In rice, we previously isolated a Moc
o mutant C25 with a mutation in the CNX2 gene from a mutagenized indica cul
tivar IR30 and characterized its biochemical properties. This mutant was cr
ossed with a japonica cultivar, Norin 8, to investigate the linkage of cnx2
to restriction fragment length polymorphism (RFLP) and cleaved amplified p
olymorphic sequence (CAPS) markers. Chlorate resistance was used to trace t
he cnx2 mutation because of its cosegregation with the loss of NR and XDH a
ctivities observed earlier. RFLP and CAPS analyses show the location of the
cnx2 locus on the long arm of chromosome 4. It is mapped between RFLP mark
ers C513 and C377 with a distance of 9.5 and 13.1 cM, respectively. It is a
lso linked with CAPS marker RA0738 at a distance of 30.3 cM.