The uptake of alkaloids by plants from the soil is determined by rhizosphere pH

Metabolic Toxification of 1,2-Unsaturated Pyrrolizidine Alkaloids Causes Human Hepatic Sinusoidal Obstruction Syndrome: The Update

“…On theoretical grounds, there are two conditions, whereby plants can acquire PAs: first, plants biosynthesize PAs using chemical intermediates as precursors and enzymes catalyzing the synthesis [ 24 ], and second, those plants that primarily cannot synthesize and therefore do not contain PAs may acquire PAs through soil or water contaminated with PAs [ 137 , 138 , 139 , 140 , 141 , 142 ]. Despite these promising data supporting the new concept of horizontal natural product transfer of PAs [ 137 , 138 , 139 , 140 , 141 , 142 ], a recently published study questioned the relevance of this phenomenon for PAs under field conditions [ 143 ], although many reports provided enough evidence that that horizontal tranfer is well functioning under field conditions for PAs [ 130 , 136 ] and various compounds such as heavy metals [ 144 , 145 , 146 , 147 , 148 ]. Indeed, the uptake of toxins by plants is known for heavy metals found to be severely contaminating soil, for instance, the vegetable Ipomoea aquatica consumed by nearby villagers [ 144 ].…”

“…With respect to PAs, much progress has been achieved within the last few years on the issue of their interactions with plants and the environment [ 137 , 138 , 139 , 140 , 141 , 142 ]. These conditions are real challenges, also recognized by the USP (United States Pharmacopeia) [ 149 ], and can help understand HSOS outbreaks from PAs in Ethiopia [ 68 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 ] and other subtropical and tropical countries [ 4 ].…”

“…These conditions are real challenges, also recognized by the USP (United States Pharmacopeia) [ 149 ], and can help understand HSOS outbreaks from PAs in Ethiopia [ 68 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 ] and other subtropical and tropical countries [ 4 ]. The various facets of this fascinating PA concept, called horizontal natural product transfer, has been presented in publications since 2015 [ 137 ] und subsequently expanded [ 138 , 139 , 140 , 141 , 142 ], and is briefly summarized: (1) it was suggested that chemicals such as PAs may undergo translocation from a rotting PA-containing plant via soil into a nearby plant through uptake by its roots [ 137 ]; (2) the transfer of PAs was investigated using various herbs as acceptor plants, which had been mulched with dried plant material from the PA-containing Senecio jacobaea as providing plants, leading to high amounts of PAs in the nearby acceptor plants and confirming the horizontal transfer of PAs [ 142 ]; (3) the transfer occurs also from vital providing plants and is not limited to rotting plants, while the uptake by the roots of the acceptor plant proceeds through simple diffusion without an active transporter system, and, most importantly, the chemical imported may undergo modification in the acceptor plant [ 143 ]; (4) studies using co-cultures of the PA-containing Senecio jacobaea with parsley as an acceptor plant, which lacks its own PA biosynthesis, showed significant amounts of PAs in acceptor plants growing near the Senecio plants, of more than 200 μg/kg dry weight, previously synthesized by the Senecio donor plants [ 140 ]; and finally, (5) the uptake of PAs from the soil by the acceptor plant is variably determined by the rhizosphere pH, the concentration of protonated and unprotonated PAs in the soil, and the transpiration rate of the plant leaves [ 142 ].…”

“…The proposed system of horizontal natural product transfer has substantially enlarged our knowledge of PA interactions in plants acquiring PAs through contaminated soil, and allows for identifying mechanistic steps, with focus on plant roots and rhizomes responsible, for PA uptake [ 137 , 138 , 139 , 140 , 141 , 142 ], and containing PAs in addition to aerial plant parts [ 56 , 133 , 150 ]. According to published evidence and illustrations [ 137 , 138 , 139 , 140 , 141 , 142 ], it seems that most of vital plants can act as acceptor plants, receiving, through their roots and rhizomes, PAs released from vital donor-PA plants or rotted donor-PA plants ( Figure 5 ).…”

Nano Zero Valent Iron (nZVI) as an Amendment for Phytostabilization of Highly Multi-PTE Contaminated Soil

“…Many authors have drawn attention to the role of pH in taking up PTEs for plants and shaping their mobility in the soil [ 36 , 37 , 38 ]. When the pH is low, cation of PTEs forms, which influences the easy migration of these elements into the soil and facilitates their availability to plants [ 39 ].…”