Sorghum () Gene Links Lignin Biosynthesis to Folate Metabolism.

Genetic analysis of brown midrib sorghum () mutant lines assembled in our program has previously shown that the mutations fall into four allelic groups, , , or . Causal genes for allelic groups , and , have since been identified. In this report, we provide evidence for the nature of the mutation. This was accomplished by introgressing each of the four alleles into nine different genetic backgrounds. Polymorphisms from four resequenced bulks of sorghum introgression lines containing either mutation, relative to those of a resequenced bulk of the nine normal midrib recurrent parent lines, were used to locate their respective causal mutations. The analysis confirmed the previously reported causal mutations for and but failed in the case of -bulk due to a mixture of mutant alleles at the locus among members of that mutant bulk. In the -bulk, a common G → A mutation was found among all members in . This gene encodes a putative folylpolyglutamate synthase with high homology to maize The brown midrib phenotype co-segregated with this point mutation in two separate F populations. Furthermore, an additional variant allele at this locus obtained from a TILLING population also showed a brown midrib phenotype, confirming this locus as .