The rhizosheath is a belowground area that acts as a communication hub at the root–soil interface to promote water and nutrient acquisition. Certain crops, such as white lupin (Lupinus albus), acquire large amounts of phosphorus (P), owing partially to exudation of acid phosphatases (APases). Plant growth-promoting rhizobacteria also increase soil P availability. However, potential synergistic effects of root APases and rhizosheath-associated microbiota on P acquisition require further research. In this study, we investigated the roles of root purple APases (PAPs) and plant growth-promoting rhizobacteria in rhizosheath formation and P acquisition under conditions of soil drying (SD) and P treatment (+P: soil with P fertilizer; –P: soil without fertilizer). We expressed purple acid phosphatase12 (LaPAP12) in white lupin and rice (Oryza sativa) plants and analyzed the rhizosheath-associated microbiome. Increased or heterologous LaPAP12 expression promoted APase activity and rhizosheath formation, resulting in increased P acquisition mainly under SD–P conditions. It also increased the abundance of members of the genus Bacillus in the rhizosheath-associated microbial communities of white lupin and rice. We isolated a phosphate-solubilizing, auxin-producing Bacillus megaterium strain from the rhizosheath of white lupin and used this to inoculate white lupin and rice plants. Inoculation promoted rhizosheath formation and P acquisition, especially in plants with increased LaPAP12 expression and under SD–P conditions, suggesting a functional role of the bacteria in alleviating P deficit stress via rhizosheath formation. Together, our results suggest a synergistic enhancing effect of LaPAP12 and plant growth-promoting rhizobacteria on rhizosheath formation and P acquisition under SD–P conditions.

We use the two-atom concurrence and the visibility of interference fringes of photons to characterize a quantum phase transition for a hybrid system consisting of an array of coupled cavities and each cavity doped with a two-level atom. We compare them with the total excitation number fluctuation. Analytical and numerical simulation results show quantum critical phenomena similar to the Mott insulator to superfluid transition. Here, the contour lines of the atomic concurrence, the visibility of interference fringes of photons, and the excitation number fluctuation in the phase diagram are consistent in the vicinity of the nonanalytic locus of the atomic concurrence.

The rhizosheath, the layer of soil tightly attached to the roots, protects plants against abiotic stress and other adverse conditions by providing a bridge from the plant root system to the soil. It reduces the formation of air gaps between the root and soil and facilitates the transportation of water at the root–soil interface. It also serves as a favourable niche for plant-growth-promoting rhizobacteria in the surrounding soil, which facilitate the absorption of soil water and nutrients. This review compares the difference between the rhizosheath and rhizosphere, and summarises the molecular and physiological mechanisms of rhizosheath formation, and identifying the causes of rhizosheath formation/non-formation in plants. We summarise the chemical and physical factors (root hair, soil-related factors, root exudates, and microorganisms) that determine rhizosheath formation, and focus on the important functions of the rhizosheath in plants under abiotic stress, especially in drought stress, phosphorus deficiency, aluminium stress, and salinity stress. Understanding the roles played by the rhizosheath and the mechanisms of its formation provides new perspectives for improving plant stress tolerance in the field, which will mitigate the increasing environmental stress conditions associated with on-going global climate change.

Understanding the mechanisms that regulate plant root growth under soil drying is an important challenge in root biology. We observed that moderate soil drying promotes wheat root growth. To understand whether metabolic and hormonic changes are involved in this regulation, we performed transcriptome sequencing on wheat roots under well-watered and moderate soil drying conditions. The genes upregulated in wheat roots under soil drying were mainly involved in starch and sucrose metabolism and benzoxazinoid biosynthesis. Various plant hormone-related genes were differentially expressed during soil drying. Quantification of the plant hormones under these conditions showed that the concentrations of abscisic acid (ABA), cis-zeatin (CZ), and indole-3-acetic acid (IAA) significantly increased during soil drying, whereas the concentrations of salicylic (SA), jasmonic (JA), and glycosylated salicylic (SAG) acids significantly decreased. Correlation analysis of total root length and phytohormones indicated that CZ, ABA, and IAA are positively associated with wheat root length. These results suggest that changes in metabolic pathways and plant hormones caused by moderate soil drying help wheat roots grow into deeper soil layers.