Analysis of Differences in Nitrogen Metabolism and Carotenoid Metabolism among Different Varieties of Flue-cured Tobacco

Abstract

【Objective】High-quality flue-cured tobacco varieties are important guarantees for showcasing the quality characteristics of tobacco producing areas. Exploring the differences in nitrogen metabolism and carotenoid metabolism characteristics between high-quality flue-cured tobacco varieties and conventional main varieties during the field growth period in Jiangxi tobacco region, and analyzing the common physiological metabolism characteristics of high-quality flue-cured tobacco varieties can provide theoretical and technical support for in-depth exploration of variety characteristics and optimization of variety matching cultivation techniques.【Method】The Minyan 312, Minyan 12 with good sensory quality and the conventional variety of Yunyan 87 (CK) were used as materials. The changes in the contents of related substances and gene expression levels in middle leaves of different varieties during key growth periods were analyzed.【Result】In terms of carotenoid metabolism, the contents of lutein and β-carotene in Minyan 312 and Minyan 12 were 3.27-6.14 mg/g and 0.67-1.59 mg/g respectively during the budding stage to foot leaf mature period, which were significantly lower than those in Yunyan 87. However, the contents of lutein in the middle leaf maturity of the two varieties were 2.31 mg/g and 2.58 mg/g, respectively, which were significantly higher than those in Yunyan 87 (0.17 mg/g and 0.44 mg/g). The peak expression of carotenoid synthesis-related genes mainly occurred in the vigorous growing period to budding stage. The relative expression of PSY and other carotenoid synthesis-related genes in Minyan 312 and Minyan 12 were higher than those in Yunyan 87 before the maturity of waist leaf, with a maximum difference of 2.53. In terms of nitrogen metabolism, the total nitrogen content (1.58%-3.36%) and protein content (7.14%-14.81%) in Minyan 312 and Minyan 12 were significantly lower than those in Yunyan 87 during the budding stage to foot leaf mature period. The expression levels of NR, NIR1 and GS1-5 genes in Minyan 312 and Minyan 12 were higher than those in Yunyan 87 during the vigorous growing period to foot leaf mature period, while the expression levels of GS1-5 genes were lower during the waist leaf mature period. In terms of correlation analysis, there was a significant or extremely significant positive correlation between NIRI, GS1-5, PSY, CRTISO and other genes, lutein and β-carotene.【Conclusion】There was a significant correlation between nitrogen metabolism and carotenoid metabolism. Compared with Yunyan 87, the middle leaves of high-quality flue-cured tobaccos Minyan 312 and Minyan 12 exhibited stronger activity of carotenoid synthesis related genes before maturity and higher lutein content during maturity in terms of carotenoid metabolism. In addition, the Minyan 312 and Minyan 12 had higher nitrogen absorption and assimilation ability before maturity, and had lower nitrogen utilization ability at maturity in terms of nitrogen metabolism.

Keywords

• flue-cured tobacco
• variety
• carotenoid
• nitrogen metabolism
• gene expression
• quality