Wrobel, M. | bioRxiv Science

bioRxiv2022

Foliar application of preparations as a method of protecting plants from the penetration of lead

Due to the contamination of soil with lead, there is still a danger of lead penetrating into our diet through crops. So far, no method has been developed to reduce the concentration of this toxic element in plants and to prevent it from entering the biological cycle. In this paper, an attempt was made for the first time to reduce lead concentrations in plants by using foliar calcium preparations. This was based on the hypothesis that an increased amount of calcium in the plant would lead to the reduction in the amount of lead as the entry routes of calcium and lead are similar; therefore, an increase in the amount of calcium will result in the saturation of the routes through which lead enters cells (e.g. calcium channels). It should be clarified that the research was experimental. Three crop species (Linum usitatissimum L., Solanum lycopersicum L., Cucumis sativus L.) were tested at the organismal level, whereas the epidermis of Allium cepa L. was used to conduct tests at the cellular level. The InCa calcium transport activator (by Plant Impact) was selected for the test, followed by calcium nitrate. The preparations were administered foliarly. Lead, on the other hand, was applied to roots before adding lead nitrate into the mineral medium. The plants were cultivated hydroponically. The growth and development of seedlings, the concentration of lead in roots and shoots and the microscopic visualisation of lead in plant organisms and cells were studied. Ultimately, the InCa activator administered foliarly was shown to reduce the concentration of lead in plant organs by approximately 44%. Further findings revealed that the mechanism of this process mainly resulted from the supply of calcium nitrate to plant leaves. A commercial calcium foliar fertiliser also showed a similar effect. The potential to reduce the uptake of lead by crops by approximately 44% is a very satisfactory result. In addition, spraying plants with InCA biostimulant and calcium nitrate is environmentally friendly. This is cutting-edge research that was described for the first time in the present paper.

plant biology↗

bioRxiv2021

ESCRT-I controls lysosomal membrane protein homeostasis and restricts MCOLN1-dependent TFEB/TFE3 signaling.

Within the endolysosomal pathway in mammalian cells, ESCRT complexes facilitate degradation of proteins residing in endosomal membranes. Recent studies revealed that yeast ESCRT machinery also sorts ubiquitinated proteins from the vacuolar membrane for degradation in the vacuole lumen. However, whether mammalian ESCRTs perform a similar function at lysosomes remained unknown. Here, we show that ESCRT-I restricts the size of lysosomes and promotes degradation of proteins from lysosomal membranes, including MCOLN1, a Ca2+ channel protein. Upon ESCRT-I depletion, the lysosomal accumulation of non-degraded proteins coincided with elevated expression of genes annotated to cholesterol biosynthesis and biogenesis of lysosomes, indicative of response to lysosomal stress. Accordingly, the lack of ESCRT-I promoted abnormal cholesterol accumulation in lysosomes and activated TFEB/TFE3 transcription factors. Finally, we discovered that in contrast to basal TFEB/TFE3 signaling that depended on the availability of exogenous lipids, the stress-induced activation of this pathway was Ca2+-MCOLN1-dependent. Hence, we provide evidence that ESCRT-I is crucial for maintaining lysosomal homeostasis and we elucidate mechanisms distinguishing basal from lysosomal stress-induced TFEB/TFE3 signaling.

cell biology↗