Anthocyanin Synthesis And Nitrogen Metabolism Interact In Crabapple Under Low Nitrogen Stress

Under low-nitrogen conditions,the color of some crabapple tissues turned red and the accumulation of anthocyanin also increased,and the metabolism levels of different forms of nitrogen were different.In this paper,the tissue culture seedlings of crabapples were used as plant materials.First,fully stretched leaves of the green-leaf crabapple were taken and induced on culture medium with different nitrogen content.3 Samples with obvious different phenotypic expression were chosen for transcriptome sequencing analysis.Key genes with significant different expression related to anthocyanin synthesis and nitrogen metabolism were selected through gene function annotation analysis,enrichment analysis,and differential gene expression.At the same time,high performance liquid chromatography were used to detect the content of anthocyanins and other flavonoids in different treated leaves.Finally,fluorescence quantitative PCR analysis was used to explore the expression of related genes in crabapple leaves under different nitrogen stress.Key genes were identified to explore the relationship between nitrogen metabolism and anthocyanin synthesis in plants,and provide clues for their mechanism of material metabolism.The results of the study are as follows:(1)Low nitrogen environment can stimulate flavonoid synthesis pathway,which is negatively correlated with anthocyanin synthesis.The most obvious changes of leaf color induced by different degrees of nitrogen stress were from 100% MS,25% MS and 20% MS,respectively.The results showed that nitrogen content could affect the synthesis of flavonoids by affecting phenylalanine metabolism.(2)The results of HPLC showed that low nitrogen stress did affect anthocyanin synthesis,and promoted the increase of naringenin,which was the intermediate product of anthocyanin production.It provided the substrate for the downstream anthocyanin synthesis,and then affected the color of plant tissues.It is speculated that the change of nitrogen content in the culture environment leads to different material distribution mechanisms in different metabolic pathways in plants.(3)qPCR analysis showed that the expression of anthocyanin pathway related genes CHI F3H,DFR,ANS and transcription factor MYB10 were positively correlated with anthocyanin synthesis under low nitrogen stress.Meanwhile,it was found that MsMYB59,MsbHLH106 and MsbHLH137 could also positively regulate anthocyanin synthesis under low nitrogen stress.MsTAT,MsPCKA and MsleuD genes,which are related to amino exchange in phenylalanine metabolism and nitrogen metabolism,may play a negative role in the regulation of anthocyanin synthesis.Two LBD genes were found to be positively correlated with anthocyanin synthesis.These genes can be used as the correlation factors between anthocyanin synthesis and nitrogen metabolism.