Construction Of Mutant Population And Screening And Analysis Of Dwarf Mutants In Pepper Through EMS Mutagenesis

Pepper(Capsicum annuum L.)is one of the main vegetable crops and favoured by people all over the world.However,the narrow genetic background limited pepper's yield and quality improvement in recent years.To improve the genetic property of peppers and functional genes study,the inbred line 6421 was selected and treated with different concentrations of mutagen(ethyl methane sulfonate(EMS))to study the effect of EMS treatments on seeds germination and some biochemical characteristics of seedlings,to construct mutant library and analyze the phenotypic traits.At the same time,certain dwarf mutants were chosen in mutant population for agronomic characters,photosynthetic pigment content determination and genetic analysis.The results showed that:(1)Treated with 1.0% EMS,the germination rate and seedling survival rate were 45.2% and 40.22%,respectively,which were close to those with LD50,the seedlings had the highest enzyme activities of superoxide dismutase(SOD,246.45 U/g),peroxidase(POD,33.99 U/g)and catalase(CAT,158.10 U/g/min),and the malondialdehyde(MDA,37.99 ?mol/g)content of seedlings was 1.85 times as much as the control.(2)10,000 LD50 of treated seeds were sowed to construct mutant population.562 mutant lines were identified in 2015,and classified into five categories: leaf,stem,fruit,fertility and growth period mutations,which were accounting for 12.73%,21.56%,6.92%,45.33% and 13.46% of the total mutation respectively.(3)The plant height,plant width,diameter of main-stem,length of main-stem,and the number of main-stem nodes of lines E29,E58,E142 and E312 were all significantly lower than that of the wild-type plant 6421.Dwarf mutant E29 had extremely short internodes with wide,thick,dark green leaf blades,whose Chl a,Chl b,Car and total Chl content were all significantly higher than that of the wild-type plant,While E312 had extremely short internodes with light green leaves and its Chl a,Chl b,Car and total Chl were all significantly lower than that of the wild-type plant;The Chl a,Chl b,Car and total Chl of E58 and E142 were different from that of the wild-type plant but had no significant difference.(4)We used EMS-induced plant morphology mutants(E29,E58,E142 and E312)as the parental plants to reciprocally cross with the control plants.F1 progeny did not have segregation.In F2 progeny,the number of normal plants of E29,E58 and E312 was near a 3:1 ratio by ?2-test.The results indicated that mutation was controlled by a single recessive gene.The study first created a mutant population from the pepper inbred line 6421,which provides not only the germplasm resources for further breeding but also direct and effective materials for genomic study of the pepper.