Comparative transcriptome analysis between high- and 1 low-growth genotypes of Eucalyptus in response to nutrient 2 stress

15 Background: The role of macro and micro nutrients have been reported in various 16 plant. However, in perennial trees, the function of multiple elements to different 17 genotypes remain to be elucidated. This study aimed at deciphering the genetic 18 architecture of physiological differences under different nutrient levels between the 19 high- and low-growth genotypes. 20 Results: Our results showed that growth traits of both genotypes at nutrient starvation 21 treatment was much lower than that at nutrient abundant treatment, indicating that 22 nutrient is essential for plant growth. However, tree height, crown width, and fresh 23 weight of different tissues of ZQUA44 were much higher than that of ZQUB15 at the 24 three nutrient levels, implicating the genetic basis of different trees is another factor 25 that varied the phenotypic performance. The differentially expressed genes (DEGs) 26 were clustered into 6 subclusters depending on different expression pattern. 27 Functional annotation of DEGs from different subclusters showed that DEGs involved 28 in glutathione metabolism, flavonoid biosynthesis and stilbenoid, diarylheptanoid and 29 gingerol biosynthesis may responsible for nutrient starvation across different 30 genotypes, while DEGs involved in carotenoid biosynthesis and starch and sucrose 31 metabolism may have diverse function in different genotypes. The DEGs encoding 32 MYB_related may responsible for nutrient deficiency of all the genotypes, while B3 33 may play different functions in different genotypes. 34 Conclusion: Our results demonstrate that different genotypes may form different 35 metabolic pathways to coordinate plant keeping survival when they face abiotic 36 stresses. Furthermore, we elucidate DEGs that may widely responsible for nutrient 37 deficiency in different treatments and DEGs that play different functions in different 38 genotypes. Finally, our funding provide adequate nutrient supply for Eucalyptus. 39 subcluster significantly enriched in metabolic pathways, galactose diterpenoid biosynthesis, biosynthesis of secondary metabolites and fatty acid biosynthesis. DEGs of subcluster 5 were significantly enriched in ribosome and monobactam biosynthesis. The DEGs that were both activated at the two genotyppes were grouped into subcluster 6, and play important roles in cutin, suberine and wax biosynthesis, nitrogen metabolism and phenylalanine, tyrosine and tryptophan biosynthesis. The pathview was used for visualization of specific pathways. The results showed that three significant KEGG pathways were obtained, including phenylpropanoid biosynthesis, plant hormone signal transduction and plant-pathogen interaction. A total of 28 DEGs were enriched in phenylpropanoid biosynthesis pathway, with divergent expression in ZQUA44 and ZQUB15. Six of the eight hormone signal transduction pathways were identified in this study, and much more DEGs were enriched in abscisic acid and salicylic acid signal transduction. Ten DEGs were identified in the plant-pathogen interaction, including WRKY33, RBOH_F, PR1 and so on.