Polymorphisms in O-methyltransferase genes are associated with stover cell wall digestibility in European maize (Zea mays L.).
BACKGROUND
OMT (O-methyltransferase) genes are involved in lignin biosynthesis, which relates to stover cell wall digestibility. Reduced lignin content is an important determinant of both forage quality and ethanol conversion efficiency of maize stover.


RESULTS
Variation in genomic sequences coding for COMT, CCoAOMT1, and CCoAOMT2 was analyzed in relation to stover cell wall digestibility for a panel of 40 European forage maize inbred lines, and re-analyzed for a panel of 34 lines from a published French study. Different methodologies for association analysis were performed and compared. Across association methodologies, a total number of 25, 12, 1, 6 COMT polymorphic sites were significantly associated with DNDF, OMD, NDF, and WSC, respectively. Association analysis for CCoAOMT1 and CCoAOMT2 identified substantially fewer polymorphic sites (3 and 2, respectively) associated with the investigated traits. Our re-analysis on the 34 lines from a published French dataset identified 14 polymorphic sites significantly associated with cell wall digestibility, two of them were consistent with our study. Promising polymorphisms putatively causally associated with variability of cell wall digestibility were inferred from the total number of significantly associated SNPs/Indels.


CONCLUSIONS
Several polymorphic sites for three O-methyltransferase loci were associated with stover cell wall digestibility. All three tested genes seem to be involved in controlling DNDF, in particular COMT. Thus, considerable variation among Bm3 wildtype alleles can be exploited for improving cell-wall digestibility. Target sites for functional markers were identified enabling development of efficient marker-based selection strategies.
Department of Agronomy, Iowa State University, Agronomy Hall, Ames, IA 50011, USA.
Everton A
EA
Brenner
Imad
I
Zein
Yongsheng
Y
Chen
Jeppe R
JR
Andersen
Gerhard
G
Wenzel
Milena
M
Ouzunova
Joachim
J
Eder
Birte
B
Darnhofer
Uschi
U
Frei
Yves
Y
Barrière
Thomas
T
Lübberstedt
D002473:Cell Wall / Q000737:chemistry*; D018744:DNA, Plant / Q000235:genetics; D056726:Genetic Association Studies; D005838:Genotype; D054643:INDEL Mutation; D008031:Lignin / Q000096:biosynthesis*; D015810:Linkage Disequilibrium; D016015:Logistic Models; D008780:Methyltransferases / Q000235:genetics*; D008957:Models, Genetic; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics
D018744:DNA, Plant; D008031:Lignin; D008780:Methyltransferases; C019608:caffeate O-methyltransferase