| Tobacco is an important economic crop in our country.Today,the aroma and safety of cigarette products are mentioned first.Utilization of heterosis is one of the effective ways to improve tobacco quality.Although the heterosis of tobacco has created enormous economic benefits in production and application,people still have very limited understanding of the mechanism of heterosis,especially the research on the heterosis of tobacco quality traits.Therefore,there is an urgent need to study the heterosis performance of quality traits and the synthetic pathways that form this quality.Polyphenolic compounds as a class of secondary metabolites in flue-cured tobacco are mainly derived from the phenylpropanoid metabolism pathway.Polyphenols have an important influence on tobacco quality,color,and smoke physiological intensity,and are an important factor in measuring tobacco quality.The higher the polyphenol content,the higher the grade of tobacco products.Polyphenol compounds also have a great influence on the growth and development of tobacco plants,resistance to pests and diseases,and stress resistance,which can increase the yield of tobacco leaves.Therefore,this study provided a theoretical basis for the improvement of tobacco quality traits and the utilization of heterosis by analyzing the agronomic traits,polyphenols content and heterosis performance of hybrid combinations,and differential expression analysis of related genes in phenylpropanoid pathways.The results of the study are as follows:1.The results of the heterosis of agronomic traits showed that the heterosis showed great differences due to the difference in traits and hybrid combinations.All four agronomic traits showed some positive mid-parent advantage and super parent advantage,among which plant height had stronger middle parent and super parent,followed by leaf width,leaf length and leaf number.Va116×TN90,GDH88×VA116,Florda301×GDH94 showed a strong heterosis in plant height,leaf length and leaf width.Va116×TN90 had the highest heterosis in plant height,Va116×TN90 and GDH94×Florda301 showed strong heterosis in leaf number.2.A method for the simultaneous determination of chlorogenic acid,caffeic acid,rutin,palatalin,quercetin and kaempferol in tobacco polyphenols was established by the optimization of ultrasonic extraction time and reagents for extraction of polyphenols.: Ultrasonic extraction for 30 min with 70% methanol.The mobile phase is water(2% glacial acetic acid)-pure methanol;the mobile phase gradient is: 0 min A:B=80:20,25 min A: B=50:50,35 min A: B=0:100,45 Min A: B=0:100;flow rate: 1ml/min;column temperature: 30° C.;injection volume: 10 ?l;detection wavelength100 nm to 600 nm.The correlation coefficient of the standard curve detected by this method is 0.99996~0.99999,the recovery rate is in the range of 95.53% to 100.62%,the coefficient of variation is less than 2%,and the RSD is between 0.13% and 1.73%,indicating that the method is accurate,reliable and reproducible.Good;can be used to detect the content of polyphenols in tobacco leaves.3.The analysis of polyphenols in the tested materials showed that the content of chlorogenic acid and rutin in tobacco is relatively high,which is the main componentof polyphenols.Hybrid F1 has certain advantages relative to its parent material in a certain polyphenol content,such as GDH88×VA116 is much higher in chlorogenic acid content than its two parent materials;VA116×TN90 also exceeds its parents in rutin content.The chlorogenic acid content was lower than its parental VA116;Florda301×GDH94 also exceeded the parents in rutin content and was lower in chlorogenic acid content than its parent GDH94.4.Correlation analysis of polyphenols content and agronomic traits found that the plant height of long-term tobacco plants was positively correlated with the content of chlorogenic acid and rutin;leaf length and leaf width were significantly positively correlated with each other..At maturity,the correlation between polyphenols accumulation and plant height was no longer significant,but leaf length was positively correlated with total polyphenols,chlorogenic acid,rutin,and pavilion content;leaf width and There was also a very significant positive correlation between chlorogenic acid and total polyphenol content,and a significant positive correlation between chlorogenic acid and rutin,and a highly significant positive correlation between chlorogenic acid,rutin,and total polyphenol content.The pavilion accumulates at the ripening stage only second to chlorogenic acid and rutin.5.Correlation analysis between polyphenols content and gene differential expression showed that there was no significant correlation between the expression levels of NtCHSA,NtSAP,NtCCoAOMT,and NtCP1 genes and the content of Eosin,chlorogenic acid,rutin,and total polyphenols.The accumulation of substances is not influenced by the expression of these genes or a certain gene,but is regulated by other genes or genes and even multiple metabolic pathways.6.The analysis of correlation between heterosis performance and gene differential expression of polyphenols content showed that there was a significant positive correlation between the dominance rate of NtSAP and NtCP1 expression and the predominance rate of rutin content in the prolonged growth genes,and the superiority of NtALDH2C4 expression and rutin content in genes.There was a very significant positive correlation between rates,and there was no significant correlation between the prevalence of other genes and the prevalence of polyphenols.There was a significant positive correlation between the expression rate of NtCCoAOMT gene in mature stage and chlorogenic acid content.There was a significant positive correlation between NtFLS1 gene and the predominance rate of caffeic acid content and a very significant positive correlation with quercetin content. |
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