Regulation Of GABA And NaCl On Lutein Accumulation In Broccoli Sprouts

Lutein is an oxygen-containing carotenoid without vitamin A activity.It is widely found in vegetables,flowers,fruits and some algae organisms.Its unique structure makes it possess a variety of physiological functions.Broccoli is a high-fiber vegetable,rich in many nutrients,and plays an important role in preventing cancer and chronic diseases.In this subject,broccoli seeds with the variety ’Qingfeng’ were used as experimental materials and germinated,and the effects of different concentrations of NaCl treatment on the physiological and biochemical,lutein content,and antioxidant enzyme activities of broccoli sprouts were studied.The optimal culture conditions for lutein accumulation in broccoli sprouts were optimized by spraying exogenous GABA,and the effects of GABA combined with NaCl treatment on carotenoids and other nutrients in broccoli sprouts were further explored,and finally the relative expression of key enzyme genes in the lutein synthesis pathway were analyzed at the genetic level.The regulation mechanism of exogenous GABA combined with NaCl on the enrichment of lutein in broccoli sprouts was preliminarily clarified,which laid a theoretical foundation for the production of broccoli sprouts with good quality and rich in lutein.The main research contents are as follows:(1)By comparing the accumulation of lutein in broccoli sprouts under different light and temperature,it was screened that temperature of 25℃ and 16h light/8h dark cycle were suitable conditions for the accumulation of lutein in sprouts.Broccoli seeds were sprayed with different concentrations of NaCl.The sprouts sprout length increased significantly under 50 and 100 mmol/L NaCl,while the 200-300 mmol/L NaCl significantly inhibited the elongation of sprouts.With the increase of NaCl concentration,the content of malondialdehyde and proline in the sprouts increased gradually.The content of lutein in the sprouts reached 546.25 μg/g when the NaCl was 100 mmol/L,which was 37.54%higher than that of the control,and its soluble protein,reducing sugar content and antioxidant enzyme activity were also significantly higher than those of the control.(2)By optimizing the culture conditions for the accumulation of lutein in broccoli sprouts,the NaCl concentration of 83.91 mM,GABA concentration of 1.18 mM and germination at room temperature for 4.38 days were obtained.The lutein content in the sprouts was 641.45 μg/g DW measured by simulating this condition,which was close to the predicted value and verified the validity of the model.In addition,the antioxidant capacity of lutein in the sprouts was significantly higher than that of the control group.The contents of neoxanthin,violaxanthin,lutein,α-cryptoxanthin,β-cryptoxanthin,α-carotene,andβ-carotene were respectively higher than those of the control,approximately increased by 68.76%,50.41%,43.49%,18.10%,11.65%,40.89%,27.34%.(3)Exogenous GABA treatment can promote the growth of broccoli sprouts and the accumulation of lutein.Under the treatment of GABA and NaCl,the fresh weight,dry weight and sprout length of broccoli sprouts increased significantly,which increased by 43.52%,83.76%,and 30.88%compared with the control,respectively.Compared with NaCl treatment alone.GABA combined with NaCl treatment increased the content of lutein and other carotenoids,glucosinolates,isothiocyanates,carotenoids and antioxidant enzyme activities in sprouts effectively.Under the combined treatment conditions,the contents of lutein and sulforaphane in leaves were significantly increased by 16.66%and 46.58%compared with the control,and the glucosinolate content in the stems was increased by 62.81%compared with the control.(4)RT-qPCR technology was used in this study to analyze the gene expression levels of key enzymes of PSY,LCYB,LCYE,HYD,ZEP,VDE,CCD1,CCD7 in the lutein metabolism pathways of broccoli sprouts under the treatment of GABA and NaCl.Compared with the treatment of NaCl alone,the expression levels of LCYB,LCYE,and VDE genes were significantly increased by 79.64%,10.14%,and 43.99%under GABA combined with NaCl treatment,and the CCD1 gene expression was significantly decreased by 25.06%.There were no significant difference in the expression levels of PSY,HYD,ZEP,and CCD7 genes.