Effect Of Diurnal Variability And Mineral Nutrition Elements On Accumulation Of Patchouli Alcohol In Pogostemon Cablin

Patchouli alcohol, one of the major components of patchouli oil and one of the active ingredients of Pogostemon cahlin, has been the index component for evaluating patchouli medicinal materials and patchouli oil quality in all of China Pharmacopoeia. Patchouli alcohol has widely been used in pharmaceuticals, food, cosmetics and daily necessities because of its antibacterial and antiviral activities, unique pleasant smell and make flavor last longer. In nature, patchouli alcohol primarily in the patchouli oil. however, It was reported that the content of patchouli alcohol was very little, which limits its large-scale production and exploitation. Therefore, it is necessary to study the biosynthesis and accumulation rules of patchouli alcohol. In this study, effect of diurnal variability and mineral elements on formation and accumulation of patchouli alcohol was studied. The content of patchouli oil, patchouli alcohol and other volatile oil components under diurnal variability and mineral elements treatments was quantitative analysis by GC-MS. Moreover, the PTS and HMGR gene expression patterns of the corresponding treatment were tested by qRT-PCR. Results were as follows:(1) During diurnal variation process, the content of patchouli oil (mean value is 0.83%) reached the maximum level at 15:00; the content of patchouli alcohol (mean value is 31.36%) peaked at 12:00; the content of ?-patchoulene (mean value is 2.50%) and farnesol (mean value is 3.83%) reached maximum levels at 3:00 and 9:00 respectively; ?-elemene(mean value is 0.75%), caryophyllene (mean value is 2.38%) and humulus (mean value is 0.96%) contents showed a similar accumulation trend, reached the maximum at 6:00; there was the almost identical dynamic change trends among the content of ?-guaiene (mean value is 6.73%), seyehellene (mean value is 4.68%) and a-bulnesene (mean value is 9.54%), and peaked at 18:00.(2) The content of patchouli oil were significantly higher with applying once low concentrations of Mn (1?M), twice high concentration of Mg (10mM) and twice Co of medium to high concentrations (0.5mM and 1mM), once application of the same concentration can significantly promote the accumulation of patchouli alcohol. ?-Guaiene and humulene contents reached the highest value with three times application of high concentration of Mg (10mM), caryophyllene and farnesyl contents were obviously inereased at applying twice of medium concentration of Mn (10?M), seyehellene and a-bulnesene contents reached maximum levels at applying once of high and low concentrations of Mg (10mM and 1mM) respectively, moreover, the highest content of ?-patchoulene and ?-elemene reached at three times application of medium concentration of Mn (10?M) and twice application of high concentration of Co (1mM).(3) Partial sequences of HMGR gene were cloned in this study with the lengths of 449bp, encoding 143 amino acids. Sequence alignment revealed a high similarity comparison to the previously published sequences in GenBank, thus, the sequence can be determined. In addition, the HMGR gene was expressed at the highest level in the roots among the three patchouli parts, but there is no significant differences in leaf and stems.(4) A study of PTS and HMGR gene expression patterns under diurnal variability by qRT-PCR showed that PTS gene transcription accumulated in the night until it reached a peak before dawn (3:00), then gradually decreased. The relative expression of HMGR gene showed the trend of low in afternoon and high at night, peaked at 12:00, the time point matched with the highest patchouli alcohol content.(5) The PTS and HMGR gene expression patterns of the corresponding Mg, Mn, and Co treatment were studied, results showed that:the expression of PTS gene were improved to different extent with applying of three concentrations of Mg, Mn, and Co. The effects of Mg, Mn, and Co on expression of HMGR were different, low concentration of Mg element (1mM) and three concentrations of Co (1?M,10?M and 100?M) had obvious promoting effect on expression of HMGR. The best treatment was high concentrations of Co.