| Chinese cabbage(Brassica rapa ssp.pekinensis)is an important vegetable crop that originated in China and is widely planted in China and East Asia.In the process of Chinese cabbage planting,early bolting will lead to early transition from vegetative growth to reproductive growth,affecting the yield and quality of leaf bulbs;In the process of Chinese cabbage seed collection,late bolting will lead to difficulty in seed breeding.Therefore,it is of great significance to study the bolting and flowering of Chinese cabbage.In this experiment,the double haploid pure line ’FT’ of Chinese cabbage was used as the test material,and a stable genetic early bolting mutant ebm7 was obtained by the EMS mutagenesis method of germinated seeds.Based on the analysis and identification of bolting characteristics and genetic characteristics of mutant ebm7,the early bolting mutant gene Brebm7 was located by using MutMap and KASP technology,and the candidate gene was cloned,sequenced and expressed.The results are as follows.1.Bolting characteristics and genetic characteristics of the early bolting mutant ebm7 in Chinese cabbageThe bolting index,5 cm days of stalk length,10 cm days of stalk length,flowering time,and plant height on the day of flowering were measured for wild-type ’FT’ and mutant ebm7 materials.The results showed that the early bolting mutant ebm7 flowered significantly earlier than the wild type ’FT’.Genetic analysis showed that the early bolting character of ebm7 was controlled by a single recessive nuclear gene.2.Mapping of the early bolting mutant gene Brebm7 in Chinese cabbageThrough MutMap sequencing analysis,the mutant gene Brebm7 was located in the4.32 Mb region of A07 chromosome.There were 7 SNP mutations in the mapping region,of which 5 were non synonymous mutations and 2 formed stop codons.BraA07g040740.3C was identified as a candidate gene for early bolting mutant gene Brebm7 according to the annotation information of Chinese cabbage genome and the results of KASP genotyping.3.Sequence variation characteristics of the candidate gene BraA07g040740.3CThe candidate gene BraA07g040740.3C was cloned and sequenced.The results showed that the candidate gene BraA07g040740.3C had a C-to-T base substitution at 6745 bp in the17 th exon,which caused the amino acid to change from tryptophan to terminator.4.Expression characteristics of the candidate gene BraA07g040740.3CThe expression of candidate gene BraA07g040740.3C in different tissues of wild type’FT’ and mutant ebm7 was analyzed by real-time PCR.The results showed that the expression level of BraA07g040740.3C in mutant ebm7 was significantly lower than that in wild type’FT’.The Arabidopsis homologous gene of BraA07g040740.3C is SDG8,so the candidate gene is named BrSDG8. |
