Transcriptome Analysis of Watermelon Responses to Low Nitrogen Stress
Nitrogen is one of the essential elements for plants,which is very important for the growth and development of watermelon.In order to elucidate the mechanism of watermelon responses to low nitrogen stress,the phenotypic changes of watermelon under continuous low nitrogen stress were analyzed,and transcriptome sequencing was performed on watermelon leaves treated with different nitrogen levels(CK,N1,N3)for 15 d using Illumina Novaseq platform.The results showed that the low nitrogen treatment promoted the underground root elongation of watermelon,but significantly inhibited the above ground plant growth.Transcriptome sequencing results showed that 121,1 184 and 516 differentially expressed genes(DEGs)were identified in CK/N1,N1/N3 and CK/N3 comparisons,respectively.A total of 12 DEGs were identified in the 3 comparisons,among which the numbers of up-regulated and down-regulated genes were 1 and 11,respectively.The down-regulated genes responded to low nitrogen stress mainly through nicotinamide synthase,bHLH transcription factor,sugar transporter,chlorophyll metabolism and other pathways,while the up-regulated gene is related to tyrosine metabolism.In conclusion,the response of watermelon growth to low nitrogen stress was a complex process,and the key genes related to nitrogen stress identified by transcripome might play an important role in improving watermelon tolerance to low nitrogen stress and improving nitrogen use ef ficiency of watermelon.Above results laid a foundation for further research on the mechanism of watermelon response to low nitrogen stress.