Genome-wide expression profiling of leaves and roots of watermelon in response to low nitrogen

Abstract

BackgroundNitrogen (N) is a key macronutrient required for plant growth and development. In this study, watermelon plants were grown under hydroponic conditions at 0.2 mM N, 4.5 mM N, and 9 mM N for 14 days.ResultsDry weight and photosynthetic assimilation at low N (0.2 mM) was reduced by 29 and 74% compared with high N (9 mM). The photochemical activity (Fv/Fm) was also reduced from 0.78 at high N to 0.71 at low N. The N concentration in the leaf, stem, and root of watermelon under low N conditions was reduced by 68, 104, and 108%, respectively compared with 9 mM N treatment after 14 days of N treatment. In the leaf tissues of watermelon grown under low N conditions, 9598 genes were differentially expressed, out of which 4533 genes (47.22%) were up-regulated whereas, 5065 genes (52.78%) were down-regulated compared with high N. Similarly in the root tissues, 3956 genes were differentially expressed, out of which 1605 genes were up-regulated (40.57%) and 2351 genes were down-regulated (59.43%), compared with high N. Our results suggest that leaf tissues are more sensitive to N deficiency compared with root tissues. The gene ontology (GO) analysis showed that the availability of N significantly affected 19 biological processes, 8 cell component metabolic pathways, and 3 molecular functions in the leaves; and 13 biological processes, 12 molecular functions, and 5 cell component metabolic pathways in the roots of watermelon. The low affinity nitrate transporters, high affinity nitrate transporters, ammonium transporters, genes related with nitrogen assimilation, and chlorophyll and photosynthesis were expressed differentially in response to low N. Three nitrate transporters (Cla010066, Cla009721, Cla012765) substantially responded to low nitrate supply in the root and leaf tissues. Additionally, a large number of transcription factors (1365) were involved in adaptation to low N availability. The major transcription factor families identified in this study includes MYB, AP2-EREBP, bHLH, C2H2 and NAC.ConclusionCandidate genes identified in this study for nitrate uptake and transport can be targeted and utilized for further studies in watermelon breeding and improvement programs to improve N uptake and utilization efficiency.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-4856-x) contains supplementary material, which is available to authorized users.

Genome-wide identification and analysis of GDSL-type esterases/lipases in watermelon (Citrullus lanatus)

“…In view of the importance of nitrogen (N) as the primary inorganic nutrient in plant growth and development, especially for crops requiring large quantities of fertilizers, such as watermelon, and the key roles of GDSL lipases in regulating plant growth and development, the expression patterns of GDSL genes in the leaf and root of watermelon under optimal nitrogen (ON) and low nitrogen (LN) conditions were investigated in this study based on the available transcriptome data published previously [39]. According to the analysis of gene expression profiling, the watermelon GDSL genes showed diverse expression patterns (Fig.…”

“…The RNA-seq data were downloaded in "fastq" format from the public database (https://www.ebi.ac.uk/), and the accession number of the study was PRJNA422970, which included 12 run accessions (SRR6389278-SRR6389289). Details about the transcriptome data and analysis of watermelon leaves and roots under low nitrogen were described and carried out in a 14 previous study [39]. Additional File Legend Table S1.…”

Nitrogen Use Efficiency of Watermelon Grafted onto 10 Wild Watermelon Rootstocks under Low Nitrogen Conditions

“…However, the response of these rootstocks on reproductive behavior and fruit quality parameters requires further investigations. Additionally, genome-wide transcriptome analysis may help understand the underlying genetic regulation mechanisms [46] involved in N uptake and its utilization.…”

Exogenous Application of Amino Acids Improves the Growth and Yield of Lettuce by Enhancing Photosynthetic Assimilation and Nutrient Availability

“…Nitrogen is an essential element for lettuce plants, an integral component of protein, phospholipid, and chloroplast [5,6]. Nitrogen uptake, assimilation, and utilization play essential roles in plant growth and development [7,8].…”