| Seeds are one of the most important food sources for human beings.Study on the mechanism of regulating seed size can provide important theoretical basis for high yield of crops.The formation of seeds requires double fertilization,that is,one sperm combines with egg cells to form embryos,and the other sperm combines with central cells to form endosperm.Among them,endosperm is the main transport and storage medium of nutrients in seed.In Arabidopsis thaliana,a model plant,the early stage of endosperm development is accompanied by a rapid process of nucleus division,and a large number of endosperm nuclei were formed in a short time.When the embryo developed to the heart-shaped stage,it started from the cells around the embryo,and the endosperm initiates a process of cellularization,which is one of the key factors to determine the seed size.It has been shown that many genetic and environmental factors are involved in the regulation of seed development.Epigenetic modification is also involved in controlling seed size.H3K27me3 is one of the key epigenetic inhibition modifications,which has been found to play an important role in regulating the expression of key genes for seed development and final seed size.However,it has not been reported whether and how the enzyme responsible for the demethylation of H3K27me3 participates in the regulation of seed size.There are six JMJD proteins in Arabidopsis thaliana,and five of them have been reported to have the function of histone demethylation.In this study,through the analysis of the mutants of ref6,elf6,jmj13,it was found that these H3K27me3 demethylases may be involved in the control of pod and seed size of Arabidopsis thaliana.JMJ13 showed obvious large seed phenotype after mutation.In this paper,JMJ13 gene is the main research object,and the mutants of ref6,elf6,jmj13 are also preliminarily studied.Through genetic and transcriptome analysis,it was found that JMJ13 was involved in the regulation of seed size,which may be controlled by an endosperm-specific gene SKS8.After JM13 mutation,it showed obvious big seed phenotype,and the pod and root of jm13 mutant became longer.After analyzing and observing its expression pattern,it was found that JM13 was expressed in the seed coat.After RNA-Seq analysis,it was found that the endosperm-specific expression gene SKS8 was down-regulated in jm13 mutant,and after overexpressing SKS8,its seed became smaller.Therefore,we believe that JMJ13 regulates the development of endosperm by regulating the seed coat and the communication between seed coat and endosperm,and finally affects the seed size.This paper provides a new perspective for studying how epigenetics inheritance in seed growth and development.The main results of this paper are summarized as follows:1.Under normal growth conditions,jmj13 mutant showed obvious large seed phenotype,but after JMJ13 was over-expressed,the seed became obviously smaller,which indicated that JMJ13 gene regulated the seed size2.We constructed the p JMJ13::Ω-H2B-Clover fluorescent vector,and obtained JMJ13 nuclear localization report vector transgenic material.The fluorescent confocal microscope showed that the reporter gene was mainly expressed in seed coat.This suggests that JMJ13 may control seed size by regulating the development of seed coat.3.Transcriptome analysis of 3-day-old seeds of jmj13 mutant,showed that SKS8 gene was down-regulated obviously in jmj13 mutant.Although SKS8 gene was specifically expressed in endosperm at the early stage of fertilization,the seed size of sks8 homozygous mutant performed no obvious seed phenotype.In this study,we found that the double mutant of jmj13/sks8 showed a larger seed phenotype than the two single mutants.4.SKS8 was overexpressed in sks8 mutant,and it was found that it showed obvious small seed phenotype. |
