Study On The Response Of Invasive Plant Bidens Alba And Local Related Species Bidens Biternata To Low Temperature Stress

Bidens alba(L.)DC is a plant of the composite family Bidens genus,native to tropical America and widely distributed in tropical and subtropical regions around the world.At present,Bidens alba has widely invaded the South Asian tropical regions of China,causing great harm to local agriculture,forestry,and ecological environment.However,the disaster mechanism of Bidens alba in the South Asian tropical regions of China is still unclear.Previous studies have found that the invasive plant Bidens alba has stronger cold tolerance than the native plant Bidens biternata(Lour.)Merr.Et Sherff,under low temperature stress,Bidens alba can form a competitive advantage and become an important mechanism for its successful invasion,but its cold tolerance mechanism is still unclear.In this study,Bidens alba was taken as the research object,and Bidens biternata as the control,to compare and analyze the phenotypic,physiological and biochemical,and transcriptome differences between the two species under low temperature stress,so as to clarify the physiological and biochemical mechanism and molecular regulation mechanism of Bidens alba under cold stress.The results are as follows:(1)Phenotypic differences: Compared with room temperature(30/24℃),under low temperature stress(12/6 ℃),The stem color of Bidens alba significantly turns purple,and the leaf color also turns purple;however,there was no significant change in the color of the stems of the Bidens biternata,and only slight changes in the color of the leaf veins were observed in the leaves;Under low temperature stress,there was no significant difference in plant height increment between Bidens alba and Bidens biternata,while the stem diameter increment of Bidens alba was significantly greater than that of Bidens biternata(P<0.001);The leaf and root biomass of Bidens alba was significantly higher than that of Bidens biternata(P<0.001),but there was no significant difference in stem biomass.(2)Physiological characteristics: Under low temperature stress,the Fv/Fm,Fv/Fo,and chlorophyll contents in the leaves of Bidens alba were significantly higher than those of Bidens biternata(P<0.01).The MDA content in various organs of Bidens alba was significantly lower than that of Bidens biternata(P<0.001).The soluble protein content and anthocyanin content in the leaves and stems of Bidens alba were significantly higher than those of Bidens biternata(P<0.001,P<0.01)The content of NSC in leaves and roots of Bidens alba was significantly higher than that in Bidens biternata(P<0.001),while there was no significant difference in NSC content in stems.The changes in physiological indicators indicate that Bidens alba is more resistant to cold.(3)Transcriptome differences: Under low temperature stress,10793 and 10064 differential genes were identified in the stems and leaves of Bidens alba,respectively,16910 and 10204 differentially expressed genes were identified in the stems and leaves of Bidens biternata,respectively.The pathways for gene enrichment in different species are also different.Research has found that in the photosynthesis antenna protein pathway,under low-temperature stress,there is a significant upregulation of genes in Bidens alba leaves in response to low temperature stress(P<0.05),while Bidens biternata leaves do not have a significant upregulation of genes in response;In the photosynthesis pathway,Psa N in PSⅠwas significantly upregulated only in the leaves of Bidens alba(P<0.05);In the sugar metabolism pathway,except for the galactose metabolism pathway in the stem of Bidens alba,the proportion of other up-regulated genes in Bidens alba to all genes(0.71,0.68,0.64)was higher than that in Bidens biternata(0.5,0.58,0.56);The anthocyanin synthesis pathway related to antioxidants was all upregulated in Bidens alba(P<0.05),and the proportion of upregulated genes in the carotenoid synthesis pathway in the leaves and stems of Bidens alba(0.85,0.77)was higher than that in Bidens biternata(0.8,0.72);Cold response transcription factors were expressed differently in the two species.In Bidens alba,ANS and MYB,the enzymes regulating anthocyanin synthesis,were significantly up-regulated(P<0.05),while in Bidens biternata,ANS and MYB transcription factors were not responsive;In Bidens alba,SWEET1,4,10,13,14,15,17,3B,etc.were significantly upregulated(P<0.05);In the Bidens biternata,SWEET1,2,10,14,and 15 were significantly upregulated(P<0.05).Conclusion: Under low temperature stress,the difference of growth,physiological index and many genes in the body show that the cold resistance of Bidens alba is stronger than that of Bidens biternata.