In the last few decades, incredible advances have been made in understanding the way of communication among members of kingdom plantae. Some plants fight for their existence and try to suppress the growth of other plants, while some share resources to benefit each other for their survival. During all these processes, plants use several biotic and abiotic mediums such as root exudates, volatile organic compounds (VOCs), and light for the interactions. Plant can change its physiological behaviors, such as change in gene regulation and induction of defense mechanism, when linked with neighboring plant through common mycorrhizal networks (CMNs). Root exudates are also critical in plant–plant interaction, since they share information, shape microbial community, and mediate recourse competition. Moreover, plants have been found warning their neighbors about pathogen attack and herbivory through the release of VOCs. This review will advance the understandings of roles of various communication media from the prospective of intra- and interspecific interactions as well as kin recognition.

Plants have evolved sophisticated mechanisms to detect various forms of danger. Damage-associated molecular patterns (DAMPs) are endogenous danger molecules that are released from damaged cells and activate the innate immunity. Recent evidence suggests that plant extracellular self-DNA (esDNA) can serve as a DAMP molecule. However, the mechanisms by which esDNA functions are largely unknown. In this study, we confirmed that esDNA inhibits root growth and triggers reactive oxygen species (ROS) production in a concentration- and species-specific manner in Arabidopsis (Arabidopsis thaliana) and tomato (Solanum lycopersicum L.). Furthermore, by combining RNA sequencing, hormone measurement, and genetic analysis, we found that esDNA-mediated growth inhibition and ROS production are achieved through the jasmonic acid (JA) signaling pathway. Specifically, esDNA induces JA production and the expression of JA-responsive genes. The esDNA-mediated growth inhibition, ROS production, and gene expression are impaired in the JA-related mutants. Finally, we found that the JA signaling pathway is required for the esDNA-elicited resistance against the pathogens Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000. This finding highlights the importance of JA signaling in esDNA-mediated biological effects, thereby providing insight into how esDNA functions as a DAMP.

Summary: Plant species‐rich systems tend to be more productive than depauperate ones. In agroecosystems, increasing crop plant diversity by including legumes often increases soil nitrogen (N) and improves soil fertility; however, such generality in outcomes of non‐leguminous crop mixture is unknown. Here, through a meta‐analysis of 174 individual cases, we explored the current global research trend of intercropping of exclusively non‐leguminous crops (IC_nl) and quantified its effect on agroecosystem productivity key metrics, for example crop plant health, soil chemistry, and microbial community under diverse experimental conditions. IC_nl increased plant biomass and disease suppression and provided a notable yield advantage over monocultures. In addition to phosphorus and potassium, IC_nl also increased plant‐available soil N, which, along with increased soil microbial abundance, was positively associated with increased soil organic matter. These positive effects were more pronounced in experiments with long duration (> 1 yr), field soil conditions, and soil pH > 7. IC_nl improves several crop productivity metrics, which could augment sustainable crop production, particularly when practiced for a long duration and in alkaline soils.

Sub-optimal temperatures can adversely affect tomato (Solanum lycopersicum) growth, and K⁺ plays an important role in the cold tolerance of plants. However, gene expression and K⁺ uptake in tomato in response to sub-optimal temperatures are still not very clear. To address these questions, one cold-tolerant tomato cultivar, Dongnong 722 (T722), and one cold-sensitive cultivar, Dongnong 708 (S708), were exposed to sub-optimal (15/10 °C) and normal temperatures (25/18 °C), and the differences in growth, K⁺ uptake characteristics and global gene expressions were investigated. The results showed that compared to S708, T722 exhibited lower reduction in plant growth rate, the whole plant K⁺ amount and K⁺ net uptake rate, and T722 also had higher peroxidase activity and lower K⁺ efflux rate under sub-optimal temperature conditions. RNA-seq analysis showed that a total of 1476 and 2188 differentially expressed genes (DEGs) responding to sub-optimal temperature were identified in S708 and T722 roots, respectively. Functional classification revealed that most DEGs were involved in “plant hormone signal transduction”, “phenylpropanoid biosynthesis”, “sulfur metabolism” and “cytochrome P450”. The genes that were significantly up-regulated only in T722 were involved in the “phenylpropanoid biosynthesis” and “plant hormone signal transduction” pathways. Moreover, we also found that sub-optimal temperature inhibited the expression of gene coding for K⁺ transporter SIHAK5 in both cultivars, but decreased the expression of gene coding for K⁺ channel AKT1 only in S708. Overall, our results revealed the cold response genes in tomato roots, and provided a foundation for further investigation of mechanism involved in K⁺ uptake in tomato under sub-optimal temperatures.

Extracellular DNA (eDNA), as a potential plant autotoxin, can cause soil sickness, negatively affecting plant growth and reducing crop yield. Some microbial taxa can degrade eDNA; however, the effect of these bacteria on plant growth and rhizosphere microbial communities is unknown. In this study, eDNA-degrading bacterial strains were screened from soils, and their eDNA-degrading ability and plant-growth-promoting characteristics were tested in vitro. The effects of the most potent eDNA-degrading strain on tomato plant growth were assessed, and changes in the rhizosphere bacterial community were analyzed using high-throughput amplicon sequencing. Among a total of more than 600 isolated strains, Pseudomonas sp. F204 showed the strongest eDNA-degradation capacity and exhibited phosphate solubilization, siderophore, and indole-3-acetic acid production abilities. Pot experiment showed that inoculation of Pseudomonas sp. F204 significantly altered tomato rhizosphere bacterial community structure and composition, and stimulated the growth of tomato seedlings. Overall, this study shows that eDNA-degrading bacteria can alter rhizosphere bacterial community and promote plant growth, and highlights the important role of soil microbial community in alleviating autotoxicity in continuous cropping systems.