Uncovering Pathways Highly Correlated to NUE through a Combined Metabolomics and Transcriptomics Approach in Eggplant

Abstract

Nitrogen (N) fertilization is one of the main inputs to increase crop yield and food production. However, crops utilize only 30–40% of N applied; the remainder is leached into the soil, causing environmental and health damage. In this scenario, the improvement of nitrogen-use efficiency (NUE) will be an essential strategy for sustainable agriculture. Here, we compared two pairs of NUE-contrasting eggplant (Solanum melongena L.) genotypes, employing GC-MS and UPLC-qTOF-MS-based technologies to determine the differential profiles of primary and secondary metabolites in root and shoot tissues, under N starvation as well as at short- and long-term N-limiting resupply. Firstly, differences in the primary metabolism pathways of shoots related to alanine, aspartate and glutamate; starch, sucrose and glycine; serine and threonine; and in secondary metabolites biosynthesis were detected. An integrated analysis between differentially accumulated metabolites and expressed transcripts highlighted a key role of glycine accumulation and the related glyA transcript in the N-use-efficient genotypes to cope with N-limiting stress. Interestingly, a correlation between both sucrose synthase (SUS)- and fructokinase (scrK)-transcript abundances, as well as D-glucose and D-fructose accumulation, appeared useful to distinguish the N-use-efficient genotypes. Furthermore, increased levels of L-aspartate and L-asparagine in the N-use-efficient genotypes at short-term low-N exposure were detected. Granule-bound starch synthase (WAXY) and endoglucanase (E3.2.1.4) downregulation at long-term N stress was observed. Therefore, genes and metabolites related to these pathways could be exploited to improve NUE in eggplant.

Transcriptome and Metabolome Analyses Reveal Mechanisms Underlying the Response of Quinoa Seedlings to Nitrogen Fertilizers

“…Mauceri et al found that under nitrogen-deficient conditions, the levels of L-aspartic acid and L-asparagine in eggplants increased, and those of particle-bound starch synthase (WAXY) and endonuclease decreased. However, in the present study, we did not observe a significant difference in L-aspartic acid and L-asparagine content [54]. GLUD1_2 is a mitochondrial enzyme that not only catalyzes the synthesis of glutamate from 2-oxoglutarate and ammonia but also catalyzes the reversible oxidative deamination of glutamate into 2-oxoglutarate, which presents a carbon skeleton for the TCA cycle and has a central function in ammonia metabolism [55,56].…”

Evaluation of three sets of advanced backcrosses of eggplant with wild relatives from different gene pools under low N fertilization conditions

“…Previous studies evaluated NUE by conducting hydroponic culture in different Solanaceae species, including tomato [ 40 , 41 ], potato [ 42 , 43 ], and eggplant [ 36 , 39 ]. Other works investigated NUE using soil cultivation methods [ 31 , 44–46 ] or combining different abiotic stresses [ 47–49 ].…”

Enhancement of Growth and Secondary Metabolites by the Combined Treatment of Trace Elements and Hydrogen Water in Wheat Sprouts

“…The expression of particular genes involved in secondary metabolites production can be influenced by the level of TCA cycle metabolites, such as acetyl-CoA, succinyl-CoA, and OAA [46]. According to a study, there was a strong correlation between the glyoxylate and dicarboxylate metabolism of two pairs of genotyped eggplants that had different nitrogen usage efficiency in secondary metabolite production [47]. Our study revealed that the effect of mixture treatment altered various metabolic pathways such as the citrate cycle, glyoxylate and dicarboxylate metabolism, and pyruvate metabolism.…”