The Study On Lignification Of Two Varieties Of Bamboo Shoots And The Preservation Of Melatonin During Cold Storage

In our study,the shoots of high bamboo?Phyllostachys prominens?and moso bamboo?Phyllostachys heterocycla cv pubescens?were chosen as the exprimented materials.To study the lignification of different varieties of bamboo shoots under the room and cold temperature,we investigated changes on the appearrance quality,lignin and cellulose contents,PAL and POD activities,and the relative expressions of transcription factors?TFs?:MYB20,MYB42,MYB43,MYB63,MYB85,SND2,NST1,VND7,and KNAST7.And then,we analysed the correlation between the expression of TFs and lignin and cellulose contents.In order to explore the protective effect of melatonin on bamboo shoots,we studied the above indicators and firmness,chroma,SOD,APX and CAT activities.The results showed as follows:1.Under the room temperature,the high bamboo shoots have been yellowed and putrefied,losed the edible value on the 6th day.However,moso bamboo shoots can be stored until the 9th day.Comrared within 6 days,the firmness of high bamboo shoots and moso bamboo shoots increased1.49kg·cm^-2 and 1.35kg·cm^-2.Meanwhile,the content of lignin and cellulose increased 8.22%and6.24%in high bamboo shoots,and increased 7.5%and 5.94%in moso bamboo shoots.Compared the activity of PAL and POD,it was higher in high bamboo shoots than in moso bamboo shoots.The above conclusions shows that the rate of lignification in high bamboo shoots is faster than moso bamboo shoots.2.The relative expressioon of MYB20,MYB43,MYB63 and MYB85 were positively correlated with the lignin content,and the expression of MYB85 was positively correlated with the content of cellulose in different varieties of bamboo shoots.The relative expression of MYB20,MYB43 and MYB63 were positively correlated with the cellulose synthesis.There was a positive correlation between the expression of MYB42 and cellulose content in high bamboo shoots.On the contrary,there was a negative correlation in moso bamboo shoots.There was a negative correlation between the expression of KNAST7,which is NAC transcription factor,and the content of lignin and cellulose.NST1 only plays a regulating role in lignification in moso bamboo shoots.3.Exogenous melatonin can significantly reduce the degree of lignification of two varieties of bamboo shoots which were stored at low temperature.Under the melatonin(1mmol·L^-1)treament,the activity of PAL and POD were significantly reduced and inhibited the synthesis of lignin.The high activity of SOD,APX and CAT maintained high content of lignin and cellulose.Thus reduced the degree of lignification,and maintained the quality of bamboo shoots.4.Under the low temperature,the relative expression of MYB42 and MYB43 of high bamboo shoots without melatonin was reduced,and it has a negative correlation with the content of lignin and cellulose.After exogenous application of melatonin in high bamboo shoots,the relative expression level of MYB20,NST1 and VND7 has significant correlation with the synthesis of ligniin and cellulose.In moso bamboo shoots,the trend of MYB42 was same as trend of NST1 in the relative expression,and the relative expression of MYB42 and NST1 have positive connection with the amount of lignin and cellulose.However,the relative expression of KNAST7 has a negetive correlation.Without melatonin,the relative expression of MYB42 has unremarkable connection with content of lignin and cellulose,after application of melatonin,there has a significant positive correlation.In conclusion,those transcription factor has regulatory effect on lignin and cellulose.