Abstract
Lignin, cellulose and hemicellulose are the three main components of the plant cell wall and can impact stalk quality by affecting cell wall structure and strength. In this study, we evaluated the lignin (LIG), cellulose (CEL) and hemicellulose (HC) contents in maize using an association mapping panel that included 368 inbred lines in seven environments. A genome-wide association study using approximately 0.56 million SNPs with a minor allele frequency of 0.05 identified 22, 18 and 24 loci significantly associated with LIG, CEL and HC at P < 1.0×10−4, respectively. The allelic variation of each significant association contributed 4 to 7% of the phenotypic variation. Candidate genes identified by GWAS mainly encode enzymes involved in cell wall metabolism, transcription factors, protein kinase and protein related to other biological processes. Among the association signals, six candidate genes had pleiotropic effects on lignin and cellulose content. These results provide valuable information for better understanding the genetic basis of stalk cell wall components in maize.
Highlights
Maize (Zea mays L.) is one of the three most important staple crops, providing protein, lipids and vitamins for billions of people around the world
With the association mapping population including 368 diverse inbred lines, the extent of the phenotypic variations was estimated for all three cell wall components, LIG, CEL and HC
The correlation among each trait revealed that HC had a weak correlation with both LIG and CEL (r = 0.24 and 0.26, P < 0.01), while CEL was positively correlated with LIG (r = 0.85, P < 0.01)
Summary
Maize (Zea mays L.) is one of the three most important staple crops, providing protein, lipids and vitamins for billions of people around the world. Along with silage maize, serves as an important energy resource for ruminant animal. The energy value of forage plants is lower and more variable[1], their stover is highly useful in animal husbandry. Improving the feeding value of forage crops is key target of silage maize breeding. Plant cell walls make a large contribution to forage utilization [2], whereas, the limited digestion of fiber in the rumen makes the feeding value of forage lower than grain [1, 3]. In breeding programs, selecting for high stalk strength and resistance to corn border causes an increase in the cell wall components [11, 12].
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