| Oil palm is considered to be one of the few plants with important and potential application value,because the palm oil accumulated in the mesocarp can account for 90%of the dry weight of the tissue.It is the second most important oil raw material in the world after soybean.At present.the research on the accumulation and metabolism of plant oils has been very extensive,but the effects of light on the growth and development of oil palm mesocarp and the molecular mechanism related to the dynamic changes of lipid metabolism have not been reported.In this study,tenera oil palm were used as materials to shading the whole cycle of oil palm fruit development.Compare the total oil content of the oil palm in the shading group and the control group,the fatty acid GC-MS analysis,the transcriptome sequencing,the fluorescence quantitative experiment,etc.Analyze the light-regulated gene expression difference,oil metabolism and the molecular mechanismits of expression regulation in the oil palm.The main findings are as follows:The extraction of total oil from the oil palm mesocarp were carried out.The methyl esterification was followed by GC-MS analysis.The results showed that the total oil in the shading group accounted for about 35%of the fresh weight in the stage fourth,and the control group accounted for about 56%.In the stage fifth,the total oil in the shading group accounted for about 63%of the fresh weight,and the control group accounted for about 76%.Under the light condition,total oil content in the middle stage of the development of the mesocarp was significantly increased.The relative content of individual fatty acids did not change significantly during the stage fourth and fifth.The relative content of unsaturated fatty acids such as C18:1,C18:2,and C18:3 was significantly different in the first three stages.Secondly,in order to clarify the regulation mechanism of lipid metabolism depending on light,we extracted the total RNA from the mesocarp in the third,fourth and fifth stages for transcriptome sequencing.Ten candidate differentially expressed genes that may respond to light regulation and affect secondary metabolism during the development of mesocarp in oil palm were selected and verified by qRT-PCR in five stages of mesocarp development.Fluorescence quantification showed that the light up-regulated the expression of MYB transcription factor and MADS factor 3 in the fourth and fifth stages.There were thirty differentially expressed TF genes in the three stages,and the most frequently screened were seven MYB transcription factor and five bHLH transcription factor;transcriptome data analysis found that the molecular biological events occurred in the three stages of the shading group and the control group were more consistent.However,there are huge differences in gene expression in cells caused by light,resulting in changes in biological pathways and differences in total lipid content and relative content of individual fatty acids.Finally,through the transcriptome data,this experiment made heat maps of the differential expression of enzyme genes involved in fatty acid metabolism,sucrose metabolism,carotenoid metabolism and ethylene biosynthesis metabolism in the shading group and the control group in the third,fourth and fifth stages.In the fatty acid metabolism,the expression of FATB and LACS was up-regulated by light,the expression of PK and PFK was up-regulated by light in sucrose metabolism.The expression of PDS and AA03 was down-regulated by light in carotenoid metabolism,and the expression of ACS and ACO was down-regulated by light in ethylene biosynthesis.In the rapid accumulation of oil,light promotes the accumulation of total oil in the mesocarp by regulating these key enzymes. |
PDF Full Text Request