Changes Of Hormones In Carrot Seeds During Germination

Carrot(Daucus carota L.)belonging to Apiaceae family,is one of the most important vegetable crops in the world and cultivate extensively.Carrots obtaining high nutritional value,have varous edible way and can be planted widely.The carrots have important economic and edible value.Carrot seeds are small and have leather qualitative outside.Therefore,water permeability is poor,the seeds have slow and irregular germination,which has a greater impact on the production of carrots.Carrot seed germination is a complex process including structural changes,material accumulation and gene regulation.At present,it is not clear that the regulation of plant hormones in the process of germination of carrot seeds.The aim of our study was to investigate the changes of hormone content during the germination of carrot seeds with different germination stages.Isolate of differentially expressed genes from carrot seeds by high throughput sequencing,in order to study the expression levels of hormone-related genes during seed germination.The effect of gibberellin on the germination of carrot seed was studied by using different concentration of gibberellin solution.The main results are as follows:1.In order to study the regulation and content changes of various hormones during the germination of carrot seeds,the contents of GA3,GA4,ABA,IAA and MeJA of the carrot seeds with different germination stages were determined.'The study found that:pretreatment could break the dormancy of seeds,promote the absorption and germination of carrot seeds.Carrot seeds had hypocotyl on the 3 d,the cotyledon expansion on the 8 d.With the germination of seeds,the content of GA3 decreased firstly,then increased and then decreased.GA4 had the highest content of 6 d in germination.IAA content increased gradually,the content of ABA decreased gradually,while the content of MeJA increased gradually.The results showed that the germination of carrot seeds was regulated by various hormones and may be regulated by more complex regulatory networks.2.The carrot seeds at 3 germination stages were used as the test materials.The transcriptome was sequenced,transcribed and sequenced,and 78,837 total unigene were assembled.The total length was 70,665,005 bp,with an average length of 896 bp.A total of 1,787 differentially expressed unigenes were found at different stages of germination,and 745 differentially expressed genes related to hormones were found.Hormone regulation of carrot seed germination has a distinct phase characteristic.Finally,the differentially expressed genes related to gibberellin were detected by fluorescent quantitative expression,and it was found that the genes related to gibberellin synthesis had the characteristics of phasic differential expression.3.Carrot seeds were treated with different concentrations of GA3 solution,and the working concentration was 0,50,100,200,250,300,350 mg/L,respectively.After soaking,the seeds were washed with distilled water and placed in the incubator.The seed germination rate was measured at 6 d after germination,and the root activity and chlorophyll content of the seedlings were measured for 10 d.The results shows that seeds treated by 200 and 250 mg/L GA3 solution had the highest germination rate,and seeds treated by 250 mg/L GA3 solution had highest seedling root vigor,seeds treated by 300 mg/L GA3 solution had the highest chlorophyll content.The results showed that soaking seeds with 200?300 mg/L GA3 solution could improve the carrot seed germination rate and growth vigor.