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The characterization of nutrient and biostimulant effects in crops is complex and needs rigorous evaluations. In this study, we evaluated morphological and molecular responses induced by microalgae (Chlorella vulgaris and Scenedesmus quadricauda) extracts in Beta vulgaris L. The two microalgae extracts were firstly characterized by CNS, Fourier transform infrared spectroscopic analysis (FT-IR), and carbon-13 nuclear magnetic resonance (13C NMR). Seedlings were grown in Hoagland’s solution under controlled conditions. After 5 days of growth, 2 mL L−1 (1 mg Corg L−1) and 4 mL L−1 (2 mg Corg L−1) of the two microalgae extracts were added to the Hoagland solution. Roots were sampled 36 h after treatments. Inductively coupled plasma spectrometry (ICP-OES) and nanofluidic real-time PCR (OpenArray system) were used for sample profiling. Fifty-three sugar beet genes putatively involved in sulfate starvation were tested in treated and untreated samples. Root morphological traits were measured by means of a scanner-based image analysis system. Multivariate statistical analysis revealed no significant changes in the ionomic profile of Hoagland’s solutions treated with the two microalgae extracts with respect to that of the untreated solution. At the molecular level, microalgae extract supplies upregulated many of the evaluated genes. Functional categorization revealed these genes to be related to various biological pathways and processes including primary and secondary metabolism and intracellular transport. At the morphological level, the treated seedlings showed significantly higher values for root traits related to soil exploration and nutrient uptake, such as total root length, fine root length (diameter < 0.5 mm), and number of root tips, than the untreated plants. These data indicate that microalgae extracts have biostimulant effects on the expression of root traits and genes related to nutrient acquisition in sugar beet. [ABSTRACT FROM AUTHOR]

In this study, a system based on omics profiling was set-up for sugar beet ( Beta vulgaris L. subsp. vulgaris ) evaluation after changes in sulfate availability. Seedlings were grown on sulfate-deprived Hoagland solution. Six days after germination, 100 μM MgSO 4 was added to the solution. Root samples were collected 36 h after treatments. WinRHIZO root-scanning approach was used for the automated image analysis of plant root morphology. Inductively Coupled Plasma Spectrometry (ICP-OES) and quadrupole-time-of-flight mass spectrometry (Q-TOF) were used for ionomic and metabolic analysis, respectively. Nanofluidic real-time PCR (OpenArray system) was used for molecular profiling. OpenArray chips were designed with TaqMan probes for 53 sugar beet genes putatively involved in sulfate nutrition. At morphological level treated seedlings showed significantly higher values ( P < 0.01) than untreated plants for root traits related to soil exploration and nutrient uptake, such as total root length, fine roots length and root tips number. ICP-OES, Q-TOF and transcriptomic data revealed changes due to sulfate availability in sugar beet samples. Two key results are highlighted in sulfate-supplied roots and leaves. Firstly, high expression levels of auxin efflux carrier component 1 (PIN) and 5-phosphoribosyl-anthranilate, precursor of tryptophan and auxin synthesis, were observed in roots. Secondly, high levels of 2-Cys peroxiredoxin BAS1, chloroplastic, thioredoxin reductase (NADPH) and cysteine synthase, chloroplastic/chromoplastic, O- acetylserine sulfhydrylase, involved in protection against oxidative stress and cysteine synthase activity, respectively, were observed in leaves. Based on our findings, the combination of evaluated omics approaches could become a key system for the evaluation of the nutritional status of sugar beet under different nutrient availability conditions.