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Garlic (Allium sativum L.) is one of the crops whose economic importance has increased considerably in recent years in Brazil. The use of plant growth-promoting bacteria (PGPB) is a useful alternative for reducing the cost of agricultural inputs and, consequently, for increasing productivity. Therefore, the main objective of this work was to isolate and evaluate potential growth promoters in plants and plant pathogenic fungi growth inhibitors using endophytic bacteria from garlic roots and bacteria from the Agricultural Microbiology Culture Collection at the Federal University of Lavras. Besides verifying improvements in the growth and physiology of garlic meristems grown in vitro under the action of PGPB. Forty-eight endophytic bacteria were identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry based on the protein profile of each isolate. Four isolates were chosen according to their ability to fix nitrogen, to produce auxin and solubilize phosphate. The cultivation of garlic meristems in tissue culture with these bacteria was established at a population level of 10 6 CFU/mL. The evaluated criteria were: (1) the colonization capacity of the bacteria inside the garlic plants determined through scanning electron microscopy; (2) the chlorophyll content; and (3) the growth of garlic plants in vitro post-PGPB inoculation. Volatiles emitted by those isolates inhibited fungi growth. The inoculation of garlic meristems with Enterobacter cloacae and Burkholderia cepacia promoted an improvement in the growth and physiological attributes of garlic, indicating the feasibility of their application as plant growth promoters for commercial cultivation., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Limitation to root growth results from forces required to overcome soil resistance to deformation. The variations in individual particle forces affects root development and often deflects the growth trajectory. We have developed transparent soil and optical projection tomography microscopy systems where measurements of growth trajectory and particle forces can be acquired in a granular medium at a range of confining pressures. We developed image-processing pipelines to analyse patterns in root trajectories and a stochastic-mechanical theory to establish how root deflections relate to particle forces and thickening of the root. Root thickening compensates for the increase in mean particle forces but does not prevent deflections from 5% of most extreme individual particle forces causing root deflection. The magnitude of deflections increases with pressure but they assemble into helices of conserved wavelength in response linked to gravitropism. The study reveals mechanisms for the understanding of root growth in mechanically impeding soil conditions and provides insights relevant to breeding of drought-resistant crops., (© 2019 The Authors New Phytologist © 2019 New Phytologist Trust.)

Live imaging is now a central component for the study of plant developmental processes. Currently, most techniques are extremely constraining: they rely on the marking of specific cellular structures which generally apply to model species because they require genetic transformations. The biospeckle laser (BSL) system was evaluated as an instrument to measure biological activity in plant tissues. The system allows collecting biospeckle patterns from roots which are grown in gels. Laser illumination has been optimized to obtain the images without undesirable specular reflections from the glass tube. Data on two different plant species were obtained and the ability of three different methods to analyze the biospeckle patterns are presented. The results showed that the biospeckle could provide quantitative indicators of the molecular activity from roots which are grown in gel substrate in tissue culture. We also presented a particular experimental configuration and the optimal approach to analyze the images. This may serve as a basis to further works on live BSL in order to study root development.