Organ‐specific responses of tomato growth and phenolic metabolism to nitrate limitation

Abstract

Phenolic compounds are secondary metabolites involved in plant innate chemical defence against pests and diseases. Their concentration varies depending on plant tissue and also on genetic and environmental factors, e.g. availability of nutrient resources. This study examines specific effects of low (LN) and high (HN) nitrogen supply on organ (root, stem and leaf) growth and accumulation of major phenolics [chlorogenic acid (CGA); rutin; kaempferol rutinoside (KR)] in nine hydroponically grown tomato cultivars. LN limited shoot growth but did not affect root growth, and increased concentrations of each individual phenolic in all organs. The strength of the response was organ-dependent, roots being more responsive than leaves and stems. Significant differences were observed between genotypes. Nitrogen limitation did not change the phenolic content in shoots, whereas it stimulated accumulation in roots. The results show that this trade-off between growth and defence in a LN environment can be discussed within the framework of the growth-differentiation balance hypothesis (i.e. GDBH), but highlight the need to integrate all plant organs in future modelling approaches regarding the impact of nitrogen limitation on primary and secondary metabolism.

Nitrogen and water limitations in tomato plants trigger negative bottom-up effects on the omnivorous predator Macrolophus pygmaeus

“…Nutritional treatment design was adapted from Han et al (2014); it was based on previous knowledge acquired on the tomato plant (see Le Bot et al 2009;Larbat et al 2012Larbat et al , 2014 and established from optimal conditions ensuring maximal growth of tomato plants in our lab conditions (see details in Han et al 2014). From DAS 8, a full nutrient solution adjusted to pH 5.5 was supplied daily to plants in a fully crossed design combining two nitrogen levels (optimal nitrogen [ON] vs. insufficient nitrogen [IN]) with two water levels (optimal water [OW] vs. drought [DT]).…”

Phytochemical profiling of tomato roots following treatments with different microbial inoculants as revealed by IT-TOF mass spectrometry

“…Other empirical formulae were assigned to cinnamic acid-like structures (CI1-3) by similarity with the CH backbone, although the presence of nitrogen suggested the presence of a primary amide derivative ( Table 2). Formation of amides with other amines, namely putrescine and spermidine, is well established in the literature for carboxylic acid metabolites in tomato extracts [16,17], thus explaining the hydrolysis of these secondary metabolites leading to the formation of CI1-3 ( Table 2). The semiquantitative distribution of CO and CI metabolites was not highly abundant, nor significantly different in root extracts derived from different bioeffector treatments and from control.…”

“…In particular, CY2 and H5 differentiate from control all roots treated with bioeffectors except B4 for the former and B1 for the latter, which strengthens the hypothesis that the inoculation of plant roots modifies their metabolism. This triggers a decreased response to stress that is ordinarily induced by either a phytopathogen attack or in the absence or scarcity of nutrients [17,18,[24][25][26][27][28]. Other variables in this axis may be seen as markers to differentiate B2 from control (U1 and U2) and from B1 (CY1, L11 and L13) (Fig.…”

“…While a current consensus holds that phenolic compounds are the main factors involved in adaptability of tomato plants to stress [16,17], it is not yet clear which metabolic pathways are influenced in roots by microorganisms when they act as biostimulants [18].…”

Effects of nitrogen and potassium fertilization on the susceptibility of tomatoes to post-harvest proliferation of Salmonella enterica

“…2). The mechanism behind this observation is not yet known, however, it has been reported that tomato varieties responded to varying levels of nitrogen nutrition by producing different levels of flavonoids and related phenolics (Larbat et al, 2012).…”