The Zea mays mutants opaque2 and opaque16 disclose lysine change in waxy maize as revealed by RNA-Seq

• Published in: Scientific reports Vol. 9; no. 1; p. 12265
• Main Authors: Wang, Wei, Niu, Suzhen, Dai, Yi, Wang, Mingchun, Li, Yan, Yang, Wenpeng, Zhao, Degang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22-08-2019
• Subjects: 38; 38/91; 631/1647/2017; 631/1647/2163; Alleles; Amylopectin - biosynthesis; Amylopectin - genetics; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Gene Expression Regulation, Plant; Humanities and Social Sciences; Inbreeding; Lysine - genetics; Lysine - metabolism; multidisciplinary; Plant Proteins - genetics; Plant Proteins - metabolism; RNA-Seq; Science; Science (multidisciplinary); Transcription Factors - genetics; Transcription Factors - metabolism; Zea mays - genetics; Zea mays - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-48478-6

In maize,
opaque2
(
o2
) and
opaque
16
(
o16
) alleles can increase lysine content, while the
waxy
(
wx
) gene can enhance the amylopectin content of grains. In our study,
o2
and
o16
alleles were backcrossed into waxy maize line (
wxwx
). The
o2o2o16o16wxwx
lines had amylopectin contents similar to those of waxy line. Their nutritional value was better than waxy line, but the mechanism by which the
o2
and
o16
alleles increased the lysine content of waxy maize remained unclear. The
o2o2o16o16wxwx
lines and their parents on kernels (18th day after pollination) were subjected to RNA sequencing (RNA-Seq). The RNA-Seq analysis revealed 272 differentially expressed genes (DEGs). Functional analyses revealed that these DEGs were mainly related to biomass metabolism. Among them, in
o2o2o16o16wxwx
lines, 15 genes encoding α-zein were down-regulated, which resulted in the reduction of α-zein synthesis and increased lysine content;
lkr/sdh1
and
Zm00001d020984.1
genes involved in the lysine degradation pathway were down-regulated, thereby inhibited lysine degradation;
sh2
,
bt2
and
ae1
genes involved in starch metabolism were upregulated, leaded to wrinkling kernel and farinaceous endosperm. Our transcriptional-level identification of key genes responsible for increased grain lysine content and farinaceous endosperm formation following introgression of
o2
and
o16
alleles should promote molecular breeding for maize quality.