LED Light Quality Affects Physiological And Biochemical Traits, And Secondary Metabolism Of Houttuynia Cordata Thunb.Seedlings

Plant growth is related to several environment factors.Light is not only an essential energy source for plant but also an important regulatory signal influences plant development.With the formation of industrialized crop cultivation model,light-emitting diode(LED)is becoming a favorable novel light scource.LED can configurate specific spectra that benefit to plant development and photomorphogenesis,also,LED has showed great advantages over traditional indoor light.Lights with various spectra were captured by their corresponding receptors,and their function varied too.At the present study,we investigated the effects of different LED lights on photosynthetic characteristics,oxidative metabolism and secondary metabolism of Houttuynia cordata Thunb.We expect to provide the basis for the plant industrialization,secondary metabolites regulation,also to enrich the information forapplication of LED on plants.Our results are as follows:1.Effects of different LED light on nitrogen metabolism and photosynthetic characteristics of Houttuynia cordata Thunb.seedlingsLED white?red and blue light improved the synthesis of soluble protein,while yellow and green light suppressed.LED yellow light showed the favorable effect on soluble sugar production,while it is not case for soluble protein generation.Except LED red,the rest LED lights we used weakened the osmotic adjustment capacity,restrained the synthesis of chl a?chl b and accordingly chlorophyll content reduced.Except LED green,the others facilitated electron transportion of PS?,while LED yellow and green reduce the light energy exchanging efficiency in PS?.2.Effects of different LED light on the oxidative metabolism of Houttuynia cordata Thunb.seedlingsWith the shorten wavelength of LED light,oxidative damage was severer,where MDA and H2O2 were increasing,so were the generation rate of superoxide anion,while LED light enhanced proline accumulation in Houttuynia cordata Thunb.seedlings.The responses of SOD?POD?CAT isozymes to LED light varied.We found that SOD isozymes are rather special where Mn-SOD and Fe-SOD presented upon LED,but no Cu,Zn-SOD appeared.The quantities ofSOD and CAT isozymes altered upon LED light,while no changes of the isozymes loci.POD isozymes were more sensitive to different LED light where both the quantity and isozymes loci altered.3.Effects of different LED light qualities on the synthesis and flavonoids properties of Houttuynia cordata Thunb.seedlingsLED light accelerated the synthesis of flavonoids.Different LED light qualities have various regulatory effects on secondary metabolism in Houttuynia cordata Thunb.seedlings,leading to the changes in contents and components of flavonoids.With the shorten of LED wavelength,the antioxidant ability of flavonoids exhibited gradual decrement,including ABTS·+,DPPH and hydroxyl free radical scavenging capacity,also the contents of quercitrin,isoquercitrin and quercetin,while the chlorogenic acid content increased.We believed that the increasing of chlorogenic acid accounts for the antioxidant capacity in Houttuynia cordata Thunb.seedlings.