Protein hydrolysates are an emerging class of crop management products utilized for improving nutrient assimilation and mitigating crop stress. They generally consist of a mixture of peptides and free amino acids derived from the hydrolysis of plant or animal sources. The present work was aimed at studying the effects and the action mechanisms of a protein hydrolysate derived from animal residues on maize root growth and physiology in comparison with the effects induced by either free amino acids or inorganic N supply. The application of the protein hydrolysate caused a remarkable enhancement of root growth. In particular, in the protein hydrolysate-treated plants the length and surface area of lateral roots were about 7 and 1.5 times higher than in plants treated with inorganic N or free amino acids, respectively. The root growth promoting effect of the protein hydrolysate was associated with an increased root accumulation of K, Zn, Cu, and Mn when compared with inorganic N and amino acids treatments. A microarray analysis allowed to dissect the transcriptional changes induced by the different treatments demonstrating treatment-specific effects principally on cell wall organization, transport processes, stress responses and hormone metabolism.

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Plant lipid-transfer proteins (LTPs) are small basic secreted proteins, which are characterized by lipid-binding capacity and are putatively involved in lipid trafficking. LTPs play a role in several biological processes, including the root nodule symbiosis. In this regard, the Medicago truncatula nodulin 5 (MtN5) LTP has been proved to positively regulate the nodulation capacity, controlling rhizobial infection and nodule primordia invasion. To better define the lipid transfer protein MtN5 function during the symbiosis, we produced MtN5-downregulated and -overexpressing plants, and we analysed the transcriptomic changes occurring in the roots at an early stage of Sinorhizobium meliloti infection. We also carried out the lipid profile analysis of wild type (WT) and MtN5-overexpressing roots after rhizobia infection. The downregulation of MtN5 increased the root hair curling, an early event of rhizobia infection, and concomitantly induced changes in the expression of defence-related genes. On the other hand, MtN5 overexpression favoured the invasion of the nodules by rhizobia and determined in the roots the modulation of genes that are involved in lipid transport and metabolism as well as an increased content of lipids, especially galactolipids that characterize the symbiosome membranes. Our findings suggest the potential participation of LTPs in the synthesis and rearrangement of membranes occurring during the formation of the infection threads and the symbiosome membrane.

Protein hydrolysates (PHs) are a class of plant biostimulants used in the agricultural practice to improve crop performance. In this study, we have assessed the capacity of a commercial PH derived from bovine collagen to mitigate drought, hypoxic, and Fe deficiency stress in Zea mays. As for the drought and hypoxic stresses, hydroponically grown plants treated with the PH exhibited an increased growth and absorption area of the roots compared with those treated with inorganic nitrogen. In the case of Fe deficiency, plants supplied with the PH mixed with FeCl3 showed a faster recovery from deficiency compared to plants supplied with FeCl3 alone or with FeEDTA, resulting in higher SPAD values, a greater concentration of Fe in the leaves and modulation in the expression of genes related to Fe. Moreover, through the analysis of circular dichroism spectra, we assessed that the PH interacts with Fe in a dose-dependent manner. Various hypothesis about the mechanisms of action of the collagen-based PH as stress protectant particularly in Fe-deficiency, are discussed.

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Life sciences such as medical, nutritional, and those related to agrarian biotechnologies are experiencing a constant increase. Therefore, food consumption is today related to health state. Aiming to create an innovative spinneret system that defines the tight correlation between high nutritional and nutraceutical value of foods and their beneficial effects on consumer's health state, we tested the effects related to the administration of 40 g of the Tonda Gentile Romana Italian hazelnut cultivar (Viterbo, Italy). To this end, we enrolled 24 subjects for a period of 14 weeks, based on a crossover design. Although several papers and reviews on hazelnut intake benefits are available, few studies have investigated the effects of hazelnut-enriched diet on plasma key parameters commonly used to ascertain the individual's well-being status. The primary endpoint of the trial was to assess LDL change related to hazelnut administration, which resulted in significant beneficial effects on cholesterol parameters (LDL dropped from 133.09 mg/dl to 119.18 mg/dl). Interestingly, despite within the normal ranges, uric acid and serum creatinine mean values significantly decreased after hazelnut intake. A significant increment was also observed for ALT (from 30.9 U/L to 35.22 U/L, P = 0.01), while GGT significantly decreased from 38.04 mg/dl at T0 to 35.27 mg/dl at T1 (P = 0.001). No significant changes were also observed in azotemia, serum iron, glycemia, AST, total bilirubin, Hb, WBCs, RBCs, platelet count, and total plasma proteins. All the blood parameters analyzed appeared to be reversible after 6 weeks from the end of the treatment. Mann-Whitney U test did not show any 634significant differences in T0 -T1 Δ% LDL considering gender, age and baseline LDL. These findings may be of help in the development of strategies for personalized nutrition and diseases management.

Protein hydrolysates (PHs) are plant biostimulants consisting of oligopeptides and free amino acids exploited in agriculture to increase crop productivity. This work aimed to fractionate a commercial collagen-derived protein hydrolysate (CDPH) according to the molecular mass of the peptides and evaluate the bioactivity of different components. First, the CDPH was dialyzed and/or filtrated and analyzed on maize, showing that smaller compounds were particularly active in stimulating lateral root growth. The CDPH was then fractionated through fast protein liquid chromatography and tested on in vitro grown tomatoes proving that all the fractions were bioactive. Furthermore, these fractions were characterized by liquid chromatography–electrospray ionization–tandem mass spectrometry revealing a consensus sequence shared among the identified peptides. Based on this sequence, a synthetic peptide was produced. We assessed its structural similarity with the CDPH, the collagen, and polyproline type II helix by comparing the respective circular dichroism spectra and for the first time, we proved that a signature peptide was as bioactive as the whole CDPH.

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