Accumulation Of ?-Ainobutyric Acid In Germinated Brown Rice And Key Enzyme Geneexpression Analysis

Because of its higher nutrition than the white rice,brown rice has got more and more attention.Brown rice will germinate under the suitable temperature and humidity,macromolecular materials such as starch and protein are degraded into reducing sugar and amino acid so that they could be easily absorbed by human body,and form a variety of physiological active ingredients,such as gamma-aminobutyric acid?gamma aminobutyric acid,GABA?,glutathione and oryzanol etc.Among them,GABA is an important amino acids neurotransmitter in the central nervous system of the mammals,It can improve brain function,adjust blood pressure,calm nerves and promote long-term memory,accelerate growth hormone secretion,regulate the function of the liver,kidney,and so on.But now most of the researches for brown rice focus on optimization of the brown rice germinating conditon,as well as the changes of each nutrient during the germinaton process.Resarch reports about the GABA enrichment mechanism during the process of brown rice germination,regulating the key enzymes of GABA accumulation and its gene expression are less.This research based on the study of the changes of physiological active ingredients related to GABA enrichment during the brown rice germination,enrichment of the GABA and activity change of key enzymes such as glutamic acid Decarboxylase?L-Glutamate Decarboxylase,GDC or GAD?and gamma-aminobutyric acid transaminase?GABA transminase,GABA-T?.Analizing the key enzyme genes which influence GABA enrichment,and then illustrating the relationship between GABA and GAD,GABA and GABA-T,so as to provide technical support for regulating the enrichment of germinated brown rice.The experimental results are as follows:?1?Germinating the brown rice within the 72 hours,the content of soluble protein,free amino acids,GSH,mda and proline were detected.The content of soluble protein reduced gradually,the content of japonica rice after 72 hours has reduced 2.44 times compared with 12hours.Long grain rice after 72 hours has reduced 2.01 times compared with 6 hours.The content of free amino acid increased firstly and then decreased,two kinds of brown rices reached the maximum value at 60 h,the long grain rice is 1.86 times higher than the japonica rice.The content of Glutathione increased firstly and then decreased,the content of GSH of two kinds of brown rices reached the maximum value when germinated after 12hours.The content change of the malondialdehyde has a smaller fluctuation,at 72 hours,the content of the malondialdehyde of two kinds of brown rices reached the highest value and have a small difference.The content of proline of two kinds of brown rices went higher and higher during the germination,reaching a maximum value at 72 hours.The content of Japonica rice glutathione,malondialdehyde,proline were lower than long grain rice.It probably due to different kinds of rice have different rate of water absorption,germination rate and enzyme catalysis degree during their germination period.?2?Detected the content of GABA and the activity of the related enzyme GAD,GABA-T,glutathione reductase.The content of GABA during the brown rice germination showed a rising trend,and reached the maximum value at 72 h.The GABA content of japonica rice is 0.24mg?g^-1,long grain rice is 0.35 mg?g^-1.The GAD activity of japonica rice reached the highest value 0.025 U?g^-1 after 24 hours germination,while long grain rice reached the highest value0.033 U?g^-1 at 48 hours.After 72 hours when the germination is stopped,the activity of GABA-T was the highest by detection japonica rice was 5.43 nmol??mgpr?min?^-1,long grain rice was as high as 7.58 nmol??mgpr?min?^-1.The glutathione reductase activity of brown rice reached the highest value when germinated for 24 hours,japonica rice was 0.90 U?g^-1 rice,long grain rice was 1.58 U?g^-1.?3?Analized the expression of AB60,AB61 gene of GAD and GABA-T1,GABA-T2 gene of GABA-T in germinated brown rice by using fluorescence quantitative PCR technology.Compared with the no-germinated brown rice.At 12 h,24 h,48 h,germination long grain rice germ AB60 expression level is not high.AB61,GABA-T1,GABA-T2 had a higher expression number when germinated for 24 hours in the long gratin rice germ.In the germinated brown rice germ,The AB60,AB61 expression number at 12 h,24 h were higher than that of 48 h;The GABA-T1,GABA-T2 expression number at 24 h,48 h were higher than that of 12 h.