Although crop domestication has greatly aided human civilization,the sequential domestication and regulation of most quality traits remain poorly understood.Here,we report the stepwise selection and regulation of majo...Although crop domestication has greatly aided human civilization,the sequential domestication and regulation of most quality traits remain poorly understood.Here,we report the stepwise selection and regulation of major fruit quality traits that occurred during watermelon evolution.The levels of fruit cucurbitacins and flavonoids were negatively selected during speciation,whereas sugar and carotenoid contents were positively selected during domestication.Interestingly,fruit malic acid and citric acid showed the opposite selection trends during the improvement.We identified a novel gene cluster(CGC1,cucurbitacin gene cluster on chromosome 1)containing both regulatory and structural genes involved in cucurbitacin biosynthesis,which revealed a cascade of transcriptional regulation operating mechanisms.In the CGC1,an allele caused a single nucleotide change in Cl ERF1 binding sites(GCC-box)in the promoter of Cl Bh1,which resulted in reduced expression of Cl Bh1 and inhibition of cucurbitacin synthesis in cultivated watermelon.Functional analysis revealed that a rare insertion of 244 amino acids,which arose in C.amarus and became fixed in sweet watermelon,in Cl OSC(oxidosqualene cyclase)was critical for the negative selection of cucurbitacins during watermelon evolution.This research provides an important resource for metabolomics-assisted breeding in watermelon and for exploring metabolic pathway regulation mechanisms.展开更多
基金supported by the Agricultural Science and Technology Innovation Program(CAAS-ASTIP-ZFRI-07)the National Key R&D Program of China(2018YFD0100704)+5 种基金the China Agriculture Research System(CARS-25-03)the National Natural Science Fund for Distinguished Young Scholars(31625021)the National Natural Science Foundation of China(31672178,31471893)the Hainan University Startup Fund KYQD(ZR)1866Project supported by Hainan Yazhou Bay Seed Laboratory(B21Y10901)the Natural Science Foundation of Hainan Province(322RC574)。
文摘Although crop domestication has greatly aided human civilization,the sequential domestication and regulation of most quality traits remain poorly understood.Here,we report the stepwise selection and regulation of major fruit quality traits that occurred during watermelon evolution.The levels of fruit cucurbitacins and flavonoids were negatively selected during speciation,whereas sugar and carotenoid contents were positively selected during domestication.Interestingly,fruit malic acid and citric acid showed the opposite selection trends during the improvement.We identified a novel gene cluster(CGC1,cucurbitacin gene cluster on chromosome 1)containing both regulatory and structural genes involved in cucurbitacin biosynthesis,which revealed a cascade of transcriptional regulation operating mechanisms.In the CGC1,an allele caused a single nucleotide change in Cl ERF1 binding sites(GCC-box)in the promoter of Cl Bh1,which resulted in reduced expression of Cl Bh1 and inhibition of cucurbitacin synthesis in cultivated watermelon.Functional analysis revealed that a rare insertion of 244 amino acids,which arose in C.amarus and became fixed in sweet watermelon,in Cl OSC(oxidosqualene cyclase)was critical for the negative selection of cucurbitacins during watermelon evolution.This research provides an important resource for metabolomics-assisted breeding in watermelon and for exploring metabolic pathway regulation mechanisms.