生长和烘烤过程中烟叶抗性淀粉含量的变化

Variations of resistant starch contents in tobacco leaves during growth and curing

为降低烤后烟叶淀粉含量(质量分数)和调控烟叶抗性淀粉的合成,以云烟87为试验材料,分析了烟叶抗性淀粉含量的变化趋势、抗性淀粉含量与直链淀粉含量的相关性以及烟叶淀粉合成相关基因的表达量。结果表明:在烟草生长发育过程中,烟叶总淀粉、抗性淀粉含量整体呈上升趋势,其中烟草生长发育中后期是抗性淀粉积累的主要时期。烟叶抗性淀粉含量与直链淀粉含量呈极显著正相关(r=0.992^(**),P<0.01);在烘烤过程中,变黄期是烟叶中抗性淀粉和非抗性淀粉降解的主要时期。烘烤过程中抗性淀粉的降解比例较低,烟叶抗性淀粉和直链淀粉含量呈显著正相关(r=0.918^(*),P<0.05);在烟草生长发育过程中淀粉合成相关基因AGPS2、AGPS3、AGPL、SS2、SBE1、ISA3、GBSS和SBE2的表达量基本呈现稳定或持续增加的趋势,其中GBSS和SBE2基因的表达量变化趋势与直链淀粉和抗性淀粉含量的变化趋势一致。GBSS1和SBE2可能是调控直链淀粉和抗性淀粉含量的关键基因。

To reduce the starch contents(mass fraction)in cured tobacco leaves and regulate the synthesis of resistant starch in tobacco leaves,the leaves of tobacco cv.Yunyan 87 were analyzed for the variations of resistant starch contents,the correlation between resistant starch contents and amylose contents,and the gene expression levels related to starch synthesis in the tobacco leaves.The results showed that the contents of total starch and resistant starch in the tobacco leaves presented an increasing trend generally during the growth of tobacco,in which the middle to late growth stage was the main accumulation period of resistant starch.There was a significant positive correlation between the resistant starch content and amylose content(r=0.992^(**),P<0.01).In the curing process,yellowing stage was the main degradation stage of resistant starch and non-resistant starch in the tobacco leaves,and the degradation proportion of resistant starch was lower.There was a significant positive correlation between resistant starch content and amylose content during curing(r=0.918^(*),P<0.05).During the growth and development of tobacco,the expression levels of starch synthesis-related genes AGPS2,AGPS3,AGPL,SS2,SBE1,ISA3,GBSS and SBE2 were basically stable or increased continuously;among them,the variation trends for GBSS and SBE2 were consistent with the variation trends of amylose content and resistant starch content.GBSS1 and SBE2 might be the key genes regulating amylose and resistant starch contents.