Extracellular DNA: Insight of a Signal Molecule in Crop Protection.

Agricultural systems face several challenges in terms of meeting everyday-growing quantities and qualities of food requirements. However, the ecological and social trade-offs for increasing agricultural production are high, therefore, more sustainable agricultural practices are desired. Researchers are currently working on diverse sustainable techniques based mostly on natural mechanisms that plants have developed along with their evolution. Here, we discuss the potential agricultural application of extracellular DNA (eDNA), its multiple functioning mechanisms in plant metabolism, the importance of hormetic curves establishment, and as a challenge: the technical limitations of the industrial scale for this technology. We highlight the more viable natural mechanisms in which eDNA affects plant metabolism, acting as a damage/microbe-associated molecular pattern (DAMP, MAMP) or as a general plant biostimulant. Finally, we suggest a whole sustainable system, where DNA is extracted from organic sources by a simple methodology to fulfill the molecular characteristics needed to be applied in crop production systems, allowing the reduction in, or perhaps the total removal of, chemical pesticides, fertilizers, and insecticides application.

Effect of hydric stress-related acoustic emission on transcriptional and biochemical changes associated with a water deficit in Capsicum annuum L.

At specific vibration frequencies like ones generated by insects such as caterpillar chewing and bee's buzz-pollination turn on the plants secondary metabolism and their respective pathways gets activated. Thus, studies report that vibrations and sound waves applied to plants improves their fitness performance. Commonly, acoustic treatments for plants have used arbitrarily random frequencies. In this work, a group of signals obtained from hydric-stressed plants was recorded as vibrational patterns using a laser vibrometer. These vibration-signals were classified as representative of each condition and then externally applied as Acoustic Emission Patterns (AEP). The present research hypothesized that specific vibration frequencies could "emulate" a plant signal through mechanical energy based on tplant's ability to recognize vibration pattern similarity to a hydric status. This investigation aimed to apply the AEP's as characteristic vibrations classified as Low hydric stress (LHS), medium hydric stress (MHS), and high hydric stress (HHS) to evaluate their effect on healthy-well watered plants at two developmental stages. In the vegetative stage, the gene expression related to antioxidant and hydric stress responses was assessed. The LHS, MHS, and HHS acoustic treatments up-regulated the peroxidase (Pod) (~2.8, 1.9, and 3.6-fold change, respectively). The superoxide dismutase (Mn-sod) and phenylalanine ammonia-lyase (Pal) genes were up-regulated by HHS (~0.23 and ~0.55-fold change, respectively) and, the chalcone synthase (Chs) gene was induced by MHS (~0.63-fold-change). At the fructification stage, the MHS treatment induced a significant increase in Capsaicin content (5.88-fold change), probably through the at3and kas gene activation. Findings are correlated for a better understanding of plant responses to different multi frequency-signals tones from vibrations with potential for agricultural applications.

Elicitores: implicaciones bioéticas para la agricultura y la salud humana / Elicitors: bioethical implications for agriculture and human health / Elicitores: implicações bioéticas para a agricultura e a saúde humana

Resumen Los compuestos agroquímicos se han utilizado en la agricultura en las últimas décadas para evitar pérdidas por plagas, nutrir la tierra, aumentar el rendimiento y la calidad de los cultivos. Sin embargo, el uso de estas sustancias en muchas ocasiones representa una fuente de contaminación ambiental y riesgos a la salud. Por ello, han surgido nuevas alternativas en la producción alimentaria, como el uso de elicitores, para consolidar una agricultura más sostenible y sin efectos adversos a la salud del consumidor. Los elicitores pueden estimular el metabolismo propio de las plantas para producir compuestos que resultarán en rasgos agronómicos deseados, como metabolitos secundarios de uso nutracéutico. En el presente artículo se muestra la perspectiva científica y ética de proyectos de investigación en los cuales se emplean diferentes elicitores para sustituir el uso de agroquímicos.

Abstract In recent decades, agrochemicals have been used in agriculture to increase crop yields and quality and avoid losses due to pests. However, the use of these substances often imply environmental contamination and potential health risks. To move towards a more sustainable agriculture with less undesirable effects to human health, a novel line of research has recently emerged, proposing alternatives for the use of agrochemicals, such as elicitors. Elicitors, either biotic or abiotic, can stimulate plants biochemical mechanism to produce compounds that will result in desired agronomic traits, such as secondary metabolites to be used as nutraceuticals. This article shows the scientific and the ethic perspective of research projects evaluating the role of different elicitors in replacing the use of agrochemicals.

Resumo Nas últimas décadas, compostos agroquímicos têm sido utilizados na agricultura para evitar pragas, nutrir o solo e aumentar a produtividade e a qualidade das plantas. No entanto, o uso dessas substâncias muitas vezes contamina o meio ambiente e traz riscos à saúde. Por isso, novas alternativas, como os elicitores, surgiram na produção alimentar a fim de consolidar uma agricultura mais sustentável, sem efeitos adversos para a saúde do consumidor. Os elicitores podem estimular o próprio metabolismo das plantas para produzir compostos que resultarão em características agronômicas desejadas, como metabólitos secundários para uso nutracêutico. Este artigo mostra a perspectiva científica e ética de projetos de pesquisa em que diferentes elicitores substituem agroquímicos.

Effects of hydric stress on vibrational frequency patterns of Capsicum annuum plants.

Plants that experience a lack of sufficient irrigation undergo hydric stress, which causes the modification of their mechanical properties. These changes include a complex network of chemical and physical signals that interact between plant-plant and plant-environment systems in a mechanism that is still not well understood, and that differs among species. This mechanical response implies different levels of vibration when the plant experiences structural modifications from self-hydraulic adjustments of flux exchange at specific frequencies, with these carrying behavioral information. To measure these signals, highly sensitive instrumentation that allows the decoding of displacement velocity and displacement of plants, which is possible through calibrated equipment such as 3D scanning laser vibrometers, is necessary. Laser vibrometry technology allows for noninvasive measurements in real-time. Physiological changes could reasonably affect the biomechanical condition of plants in terms of the frequency (hertz) and intensity of the plant's vibration. In this research, it is proposed that the frequency changes of a plant's vibration are related to the plant's hydric condition and that these frequency vibrations have the ecological potential to communicate water changes and levels of hydric stress. The peak of the velocity of plant displacements was found to vary from 0.079 to 1.74 mm/s, and natural frequencies (hertz) range is between 1.8 and 2.6 Hz for plants with low hydric stress (LHS), between 1.3 and 1.6 Hz for plants with medium hydric stress (MHS), and between 6.7 and 7.8 Hz for plants with high hydric stress. These values could act as preliminary references for water management using noninvasive techniques and, knowledge of the range of natural frequencies of hydric stress risk in chili pepper crops can be applied in precision agriculture practices.