Gene Mapping Of Rice Brown Hull And Analysis Of Its Transcriptome And Metabolome

As an important part of rice spikelets,rice hull have the functions of protecting flower organs and seeds from insects and germs,and resisting the penetration of ultraviolet rays,etc.,so they play an important role in affecting rice yield and quality.Generally,the rice hull is green and turned light yellow after maturation;brown hull is usually caused by the accumulation of flavonoid.Flavonoids have antioxidant properties and are widely involved in the plant’s anti-stress reaction,and they can also attract pollinators,such as insects,to help pollination.Therefore they are one of the most important secondary metabolites in plant.CN88S is a photoperiod-/thermo-sensitive sterile rice variety with brown rice hull.In this study,we analyzed the pigmentation of rice hull of CN88S by using the method of map-based cloning,transcriptome and metabolome.The main research results are as follows:1)By using the F2 generation of CN88S/R600 to perform Map-based cloning and BSA-seq,we successfully mapped a key gene that regulates the color of rice hull,and named the gene Os BH24.Os BH24,which encoding a kelch repeat-containing F-box protein,is an allele of rice hull color genes ibf1 and osfbx310.Phylogenetic analysis showed that Os BH24 is a homologous gene of KFB^CHS.KFB^CHS encodes a kelch repeat-containing F-box protein and regulates flavonoids biosynthesis by mediating the ubiquitination and hydrolysis of chalcone synthetase.2)A transcriptome analysis of rice hull of CN88S revealed that the differential genes were significantly enriched in the flavonoid metabolism pathway.Most genes related to flavonoids synthesis and transcription factors regulating flavonoids metabolism were significantly up-regulated during pigmentation,and Os BH24 was also significantly up-regulated.3)The flavonoids metabolome analysis was performed on the rice hull of CN88S,and a total of 270 flavonoid metabolites were detected,of which a total of 49 flavonoid metabolite contents were significantly different.and 44 of them increased significantly,5 of them decreased significantly.The flavonoids with significant differences are mainly flavones and flavonols.Based on the of genome,transcriptome,metabolome and related research,it is speculated that Os BH24 which encoding a kelch repeat-containing F-box protein is involved in the post transcriptional regulation of flavonoid pathway in rice.The mutation of Os BH24 resulted in a significant accumulation of flavonoids in the rice hull and eventually made the hull of CN88S become brown.