An Integrated Multilevel Approach Unveils Complex Seed-Nanoparticle Interactions and Their Implications for Seed Priming

Nanotechnology has the potential to revolutionize agriculture with the introduction of engineered nanomaterials. However, their use is hindered by high cost, marginal knowledge of their interactions with plants, and unpredictable effects related to massive use in crop cultivation. Nanopriming is an innovative seed priming technology able to match economic, agronomic, and environmental needs in agriculture. The present study was focused on unveiling, by a multilevel integrated approach, undisclosed aspects of seed priming mediated by iron oxide magnetic nanoparticles in pepper seeds (Capsicum annuum), one of the most economically important crops worldwide. Inductively coupled plasma atomic emission mass spectrometry and scanning electron microscopy were used to quantify the MNP uptake and assess seed surface changes. Magnetic resonance imaging mapped the distribution of MNPs prevalently in the seed coat. The application of MNPs significantly enhanced the root and vegetative growth of pepper plants, whereas seed priming with equivalent Fe concentrations supplied as FeCl3 did not yield these positive effects. Finally, global gene expression by RNA-sequencing identified more than 2,200 differentially expressed genes, most of them involved in plant developmental processes and defense mechanisms. Collectively, these data provide evidence on the link between structural seed changes and an extensive transcriptional reprogramming, which boosts the plant growth and primes the embryo to cope with environmental challenges that might occur during the subsequent developmental and growth stages.

Active vs. Passive Thermal Imaging for Helping the Early Detection of Soil-Borne Rot Diseases on Wild Rocket [Diplotaxis tenuifolia (L.) D.C.]

Cultivation of wild rocket [Diplotaxis tenuifolia (L.) D.C.] as a baby-leaf vegetable for the high-convenience food chain is constantly growing due to its nutritional and taste qualities. As is well known, these crops are particularly exposed to soil-borne fungal diseases and need to be effectively protected. At present, wild rocket disease management is performed by using permitted synthetic fungicides or through the application of agro-ecological and biological methods that must be optimized. In this regard, the implementation of innovative digital-based technologies, such as infrared thermography (IT), as supporting systems to decision-making processes is welcome. In this work, leaves belonging to wild rocket plants inoculated with the soil-borne pathogens Rhizoctonia solani Kühn and Sclerotinia sclerotiorum (Lib.) de Bary were analyzed and monitored by both active and passive thermographic methods and compared with visual detection. A comparison between the thermal analysis carried out in both medium (MWIR)- and long (LWIR)-wave infrared was made and discussed. The results achieved highlight how the monitoring based on the use of IT is promising for carrying out an early detection of the rot diseases induced by the investigated pathogens, allowing their detection in 3-6 days before the canopy is completely wilted. Active thermal imaging has the potential to detect early soil-borne rotting diseases.

A molecular dynamics approach to the structural characterization of amyloid aggregation

A novel computational approach to the structural analysis of ordered beta-aggregation is presented and validated on three known amyloidogenic polypeptides. The strategy is based on the decomposition of the sequence into overlapping stretches and equilibrium implicit solvent molecular dynamics (MD) simulations of an oligomeric system for each stretch. The structural stability of the in-register parallel aggregates sampled in the implicit solvent runs is further evaluated using explicit water simulations for a subset of the stretches. The beta-aggregation propensity along the sequence of the Alzheimer's amyloid-beta peptide (Abeta(42)) is found to be highly heterogeneous with a maximum in the segment V(12)HHQKLVFFAE(22) and minima at S(8)G(9), G(25)S(26), G(29)A(30), and G(38)V(39), which are turn-like segments. The simulation results suggest that these sites may play a crucial role in determining the aggregation tendency and the fibrillar structure of Abeta(42). Similar findings are obtained for the human amylin, a 37-residue peptide that displays a maximal beta-aggregation propensity at Q(10)RLANFLVHSSNN(22) and two turn-like sites at G(24)A(25) and G(33)S(34). In the third application, the MD approach is used to identify beta-aggregation "hot-spots" within the N-terminal domain of the yeast prion Ure2p (Ure2p(1-94)) and to design a double-point mutant (Ure2p-N4748S(1-94)) with lower beta-aggregation propensity. The change in the aggregation propensity of Ure2p-N4748S(1-94) is verified in vitro using the thioflavin T binding assay.