Xingxue
Mao^1,2†,  Jianjun Zhang^3†,  Wuge Liu^1,2†,  Shijuan Yan⁴,  Qing Liu^1,2, Hua Fu^1,2,  Junliang Zhao^1,2, Wenjie Huang⁴,  Jingfang Dong^1,2,  Shaohong Zhang^1,2,  Tifeng Yang^1,2,  Wu Yang^1,2,  Bin Liu^1,2* and Feng Wang^1,2*

Rice

Abstract

Background: Seed
dormancy directly affects the phenotype of pre-harvest sprouting, and
ultimately affects the quality and yield of rice seeds. Although many genes
controlling seed dormancy have been cloned from cereals, the regulatory
mechanisms controlling this process are complex, and much remains unknown. The
MAPK cascade is involved in many signal transduction pathways. Recently, MKK3 has been reported to be involved in
the regulation of seed dormancy, but its mechanism of action is unclear.

Results: We
found that MKKK62-overexpressing rice lines (OE) lost seed dormancy. Further
analyses showed that the abscisic acid (ABA) sensitivity of OE lines was
decreased. In yeast two-hybrid experiments, MKKK62 interacted with MKK3, and
MKK3 interacted with MAPK7 and MAPK14. Knock-out experiments confirmed that
MKK3, MAPK7, and MAPK14 were involved in the regulation of seed dormancy. The
OE lines showed decreased transcript levels of OsMFT, a homolog of a gene that
controls seed dormancy in wheat. The up-regulation of OsMFT in MKK3-knockout
lines (OE/mkk3) and MAPK7/14-knockout
lines (OE/mapk7/mapk14) indicated
that the MKKK62-MKK3-MAPK7/MAPK14 system controlled seed dormancy by regulating
the transcription of OsMFT.

Conclusion: Our
results showed that MKKK62 negatively
controls seed dormancy in rice, and that during the germination stage and the
late stage of seed maturation, ABA sensitivity and OsMFT transcription are
negatively controlled by MKKK62. Our
results have clarified the entire MAPK cascade controlling seed dormancy in
rice. Together, these results indicate that protein modification by phosphorylation
plays a key role in controlling seed dormancy.

Keywords: Rice
(Oryza sativa L.),  Pre-harvest
sprouting, Dormancy, MAPK cascade

附件：The MKKK62-MKK3-MAPK7/14 module negatively regulates seed dormancy in rice