Biosynthesis Of Betacyanins In Suaeda Salsa Under The Combined Stress Of Low Nitrogen,Low Phosphorus And High Salt And Its Effect On Plant Salt Tolerance

Suaeda salsa L.is a typical annual euhalophyte and saline-alkali indicator plant.It can finish its life cycle under 3% salinity conditions.There are two phenotypes in nature: red type and green type.Pigments in red Suaeda salsa were identified as betacyanins.so far,the red phenotype of Suaeda salsa can not be mimicked under laboratorial conditions.Few information has been obtained concerning the accumulation regularity,Influencing factors and implication of betacyanins in Suaeda salsa under natural conditions.Hence,in this study,effects of salt,low nitrogen,salt + nitrogen,low phosphorus and salt + phosphorus treatment on betacyanins components and contents were analyzed.Furthermore,the relationship between betacyanins accumulation and salt tolerance of Suaeda salsa had been investigated.The main results were as follows:1.salt,low nitrogen and low phosphorus treatment alone could not induce a large accumulation of betacyanins in Suaeda salsa,but the treatment of salt + nitrogen and salt + phosphorus could significantly induce the accumulation of betacyanins in Suaeda salsa.The induction effect of salt + phosphorus treatment is not as good as that of salt + nitrogen treatment.2.The common components of betacyanins induced by salt + nitrogen treatment and salt + phosphorus are amaranthin,betanin,celosianin II,isocelosianin II.6'-O-malonyl-amaranthin and isobetanin were only detected in the salt + nitrogen treatment,6'-O-malonyl-celosianin II and 6'-O-malonyl-Isocelosianin II was only detected in the salt + phosphorus treatment.3.Treatment with 400 mM NaCl caused salt stress to Suaeda salsa,it inhibited the growth of Suaeda salsa.4.The treatment of salt + nitrogen could significantly alleviate the symptoms of salt stress by increasing betacyanins content instead of enhancing antioxidant enzymes activities in Suaeda salsa.The large accumulation of betacyanins may be related to its salt tolerance in Suaeda salsa.The treatment of salt + phosphorus failed to significantly alleviate the symptoms of salt stress in Suaeda salsa.It is possible that the difference in the components of betacyanins induced by the two treatments,betanin,celosianin II,and isocelosianin II.are responsive to salt stress.5.Transcriptome sequencing analysis was performed on leaves of Suaeda salsa L.treated with control,salt,low nitrogen,salt + nitrogen.A total of 110054 Unigenes were assembled by splicing,and 46066 Unigenes were annotated.There are 1500 differentially expressed genes,616 up-regulated and 884 down-regulated.The differentially expressed genes are annotated to Tyrosine metabolism,Photosynthesis,Nitrogen metabolism,and many other metabolic pathways.