干旱胁迫对不同品系藜麦内黄酮和抗氧化性的影响

Effects of Flavonoids Content and Key Enzymes and Antioxidant Activities of Flavonoids in Different Quinoa on Drought Stress

利用不同浓度的PEG溶液模拟干旱胁迫,分析了干旱胁迫下不同品系藜麦叶片中黄酮类化合物合成上游的苯丙氨酸解氨酶(PAL)、肉桂酸4-羟基化酶(C4H)及4-香豆酸辅酶A连接酶(4CL)此3个关键酶的活性以及种子内黄酮含量和清除DPPH·能力,探究干旱胁迫对不同藜麦种子内黄酮合成以及体外抗氧化活性的影响。结果表明:(1)随着干旱胁迫增加,三种酶活性均成先增后降趋势,但不同酶之间存在差异,PAL和4CL在5%PEG胁迫下达到最大,藜麦品系NK1、NK2和NK5的C4H活性在10%PEG时达到最大,但NK3和NK4在5%PEG胁迫下达到最大;在CK和5%PEG胁迫下藜麦品系NK3的3种酶活性较高,但在10%PEG和15%PEG胁迫下酶活性迅速降低。(2)随着干旱胁迫加剧,各品系藜麦种子内黄酮含量呈先上升后下降的趋势,在CK和5%PEG胁迫下,藜麦品系NK3种子黄酮含量最高分别为2.94 mg/g和3.61 mg/g,在10%PEG和15%PEG胁迫下,NK5种子黄酮含量最高分别是2.92 mg/g和2.66 mg/g。(3)抗氧化试验表明,各品系藜麦种子内黄酮对DPPH·的清除率在5%PEG胁迫处理时达到最大,NK1、NK2、NK3、NK4和NK5清除率分别是88.52%、87.65%、90.36%、86.53%和89.38%,其中NK3 IC50(半抑制浓度)最大为9.871μg/mL。本研究结果为理解藜麦体内黄酮合成体系和抗氧化剂资源的筛选提供理论依据。

Different con centrations of PEG solution were used to simulate drought stress.The activities of phenylalanine ammonia-lyase (PAL),cinnamate 4-hydroxylase (C4H)and 4-coumaric acid coenzyme A ligase (4CL)in leaves of different strains of Chenopodium triplex under drought stress were analyzed.The effects of drought stress on the content of flavonoids in different quinoa seeds were studied and their antioxidant activities in vitro were measured.The results showed that:(1)With the increase of drought stress,the activity of the three enzymes increased first and then decreased,but there were differences among different enzymes.PAL and 4CL reached the maximum under 5%PEG stress,C4H activity of quinoa strain NK1,NK2 and NK5 reached the maximum at 10% PEG but NK3 and NK4 reached the maximum under 5% PEG stress.The activity of the three enzymes of NK3 was higher at the concentrations of CK and 5% PEG but the enzyme activity was rapidly decreased at the concentrations of 10% PEG and 15% PEG.(2)With the intensification of drought stress,the content of flavonoids in all varieties of quinoa seeds first increased and then decreased.Under the stress of CK and 5% PEG,flavonoids in quinoa seeds increased firstly and then decreased.The highest flavonoids content of quinoa NK3 seeds was 2.94 mg/g and 3.61 mg/g,respectively.Under 10% PEG and 15% PEG stress,the highest fiavonoids content of NK5 seed was 2.92 mg/g and 2.66 rag/g,separately.(3)The antioxidant experiments showed that the scavenging rate offlavonoids from quinoa seeds to DPPH*reached the maximum in 5%PEG stress treatment,and NKI,NK2, NK3,NK4 and NK5 were 88.52%,87.65%,90.36%,86.53% and 89.38%,respectively.Among them,the NK3 IC50 (semi-inhibitory concentration)was 9.871 tzg/mL.The results provided theoretical basis for the identification of flavonoids synthesis system and antioxidant resources in quinoa.