Effects Of Salt Stress On Transcriptome And Metabolism Of Seedings Of Dendrocalamopsis Oldhami And Phyllostachys Heterocycla

Bamboo is an important forest resource plant in China,which has high economic value and ecological value.Some of the bamboo growing along the coast has salt tolerance,which can bring economic and ecological benefits to the region.In this paper,the salt tolerance mechanism of bamboo was studied by transcriptome and metabonomics,providing a theoretical basis for identifying salt tolerant bamboo species and studying the salt tolerance mechanism of bamboo.According to the results of previous tests,Dendrocalamopsis oldhami were used as salt tolerant materials and Phyllostachys heterocycla were used as lower salt tolerant materials.After 21 days salt treatment,the control group and the treatment group of Dendrocalamopsis oldhami seeding and Phyllostachys heterocycla seeding was sequenced with the transcriptomics and metabonomics of the seedlings were detected by HPLC-MS.The difference of salt tolerance between two species of bamboo was studied by two omics.In Dendrocalamopsis oldhami seedlings,2797 differentially expressed genes were detected by using no-reference transcriptome,including 614 up-regulated genes and 2183 down-regulated genes.In Phyllostachys heterocycla 562 differentially expressed genes were identified by transcriptome analysis,including 114 up-regulated genes and 448 down regulated genes.In the screening of differential metabolites,there were 58 different metabolites in Dendrocalamopsis oldhami,13 up-regulated and 45 down-regulated;Phyllostachys heterocycla had 29 different metabolites,11 up-regulated and 18 down-regulated.After salt stress,the transcripts of the two seedling plants significantly enriched the functions and pathways of photosynthesis related genes.The results of transcriptome analysis showed that,Effects of salt treatment on light absorption of photosystem I in Dendrocalamus oldhami system were significantly down regulated;The genes related to Phyllostachys heterocycla photosystem I,photosystem II and dark reaction process were significantly downregulated.The photosynthesis of Phyllostachys heterocycla was more affected by salt stress.The results showed that there was a Significant difference in tryptamine metabolism between Dendrocalamus oldhami and Phyllostachys heterocycla.The content of 5-hydroxytryptamine in seedlings of Dendrocalamopsis oldhami decreased significantly and it increased significantly in Phyllostachys heterocycla after salt treatment.In the flavonoid biosynthesis,there were significant differences between the two kinds of seedlings.In Dendrocalamopsis oldhami seedlings,Flavonoid 3 ’-monooxygenase(EC 1.14.14.82),flavanone 4-reductase(EC: 1.1.1.219 1.1.1.234)and shikimate o-hydroxycinnamoyltransferase(EC: 2.3.1.133)were significantly up-regulated;The expression of shikimate o-hydroxycinnamoyltransferase(EC: 2.3.1.133)gene was down regulated.In Dendrocalamopsis oldhami seedlings,flavonoid biosynthesis was significantly enriched,but not in the Phyllostachys heterocycla.The content of chlorogenic acid and caffeic acid increased in the two seedlings after salt treatment,and the content in Phyllostachys heterocycla was higher than that in Dendrocalamopsis oldhami.Under high concentration salt treatment(≥ 0.75%),the growth of Dendrocalamopsis oldhami was not significantly inhibited,while the growth of Phyllostachys heterocycla was significantly inhibited,and the embryo does not germinate normally.Compared with Phyllostachys heterocycl seedlings,Dendrocalamopsis oldhami seedlings were more active in the metabolism of tryptamine and flavonoids.These metabolites can improve the antioxidant activity of plants,which is consistent with the results of previous studies that the membrane damage of Dendrocalamopsis oldhami seedlings is lower than that of Phyllostachys heterocycla.Salt stress forced Dendrocalamopsis oldhami to improve its antioxidant activity and chloroplast membrane stability by increasing the content of antioxidant metabolites,This makes Dendrocalamopsis oldhami have stronger photosynthetic efficiency than Phyllostachys heterocycla under salt stress,and improves its survival ability under salt stress.