Search

The relative performance of rhizobial strains could depend on their resource allocation, environmental conditions, and host genotype. Here, we used a high-throughput shoot phenotyping to investigate the effects of Mesorhizobium strain on the growth dynamics, nodulation and bacteroid traits with four chickpea (Cicer arietinum) varieties grown under different water regimes in an experiment including four nitrogen sources (two Mesorhizobium strains, and two uninoculated controls: nitrogen fertilised and unfertilised) under well-watered and drought conditions. We asked three questions. Does the impact of rhizobial strains on chickpea growth change with well-watered versus drought conditions? Do Mesorhizobium strains differ in their ability to influence biomass and nodule traits of chickpea varieties under well-watered and drought conditions? Are bacteroid size and amount of polyhydroxybutyrate modified by Mesorhizobium strain, chickpea variety, water availability and their interactions? Under well-watered conditions, chickpea inoculated with CC1192 showed higher shoot growth rates than M075 and accumulated high plant biomass at harvest. Under drought conditions, however, the shoot growth rate was comparable between CC1192 and M075, with no significant difference in plant biomass and symbiotic effectiveness at harvest. Across sources of variation, plant biomass varied 3.0-fold, nodules per plant 3.9-fold, nodule dry weight 3.0-fold, symbiotic effectiveness 1.5-fold, bacteroid size 1.4-fold and bacteroid polyhydroxybutyrate 1.4-fold. Plant biomass was negatively correlated with both bacteroid size and allocation to polyhydroxybutyrate under well-watered conditions, suggesting a trade-off between plant and rhizobial fitness. This study demonstrates the need to reassess rhizobial strain effectiveness across diverse environments, recognising the dynamic nature of their interaction with host plants.

BackgroundSmarthouses capable of non-destructive, high-throughput plant phenotyping collect large amounts of data that can be used to understand plant growth and productivity in extreme environments. The challenge is to apply the statistical tool that best analyzes the data to study plant traits, such as salinity tolerance, or plant-growth-related traits.ResultsWe derive family-wise salinity sensitivity (FSS) growth curves and use registration techniques to summarize growth patterns of HEB-25 barley families and the commercial variety, Navigator. We account for the spatial variation in smarthouse microclimates and in temporal variation across phenotyping runs using a functional ANOVA model to derive corrected FSS curves. From FSS, we derive corrected values for family-wise salinity tolerance, which are strongly negatively correlated with Na but not significantly with K, indicating that Na content is an important factor affecting salinity tolerance in these families, at least for plants of this age and grown in these conditions.ConclusionsOur family-wise methodology is suitable for analyzing the growth curves of a large number of plants from multiple families. The corrected curves accurately account for the spatial and temporal variations among plants that are inherent to high-throughput experiments.

SUMMARY: Soil salinity is a major environmental stressor affecting agricultural productivity worldwide. Understanding plant responses to salt stress is crucial for developing resilient crop varieties. Wild relatives of cultivated crops, such as wild tomato, Solanum pimpinellifolium, can serve as a useful resource to further expand the resilience potential of the cultivated germplasm, S. lycopersicum. In this study, we employed high‐throughput phenotyping in the greenhouse and field conditions to explore salt stress responses of a S. pimpinellifolium diversity panel. Our study revealed extensive phenotypic variations in response to salt stress, with traits such as transpiration rate, shoot mass, and ion accumulation showing significant correlations with plant performance. We found that while transpiration was a key determinant of plant performance in the greenhouse, shoot mass strongly correlated with yield under field conditions. Conversely, ion accumulation was the least influential factor under greenhouse conditions. Through a Genome Wide Association Study, we identified candidate genes not previously associated with salt stress, highlighting the power of high‐throughput phenotyping in uncovering novel aspects of plant stress responses. This study contributes to our understanding of salt stress tolerance in S. pimpinellifolium and lays the groundwork for further investigations into the genetic basis of these traits, ultimately informing breeding efforts for salinity tolerance in tomato and other crops. Significance Statement: While wild tomato relative, Solanum pimpinellifolium, has been previously used for agronomic improvements of cultivated tomato, its contributions in abiotic stress tolerance remain underexplored. Here, we developed a well genotyped diversity panel of S. pimpinellifolium and screened it under greenhouse and field conditions for salt stress tolerance. This study provides genetic resources, as well as initial identification of accessions and genetic loci underlying salt tolerance in wild tomato. [ABSTRACT FROM AUTHOR]

Societal Impact Statement Summary Arbuscular mycorrhizal (AM) fungi support plant development by enhancing growth and resistance to pathogens through mycorrhiza‐induced resistance (MIR). However, the varying capacities of individual AM fungal species to induce MIR are not well‐understood, limiting their agricultural potential. This study reveals that specific AM fungal isolates differ in their ability to enhance tomato growth and reduce biomass losses due to Rhizoctonia solani infection, a major root pathogen. By identifying MIR‐effective fungal isolates and linking them to shifts in root‐associated chemical composition, we highlight potential to improve crop resilience and productivity, advancing agriculture by enabling more efficient use of AM fungi. Mycorrhiza‐induced resistance (MIR) can increase plant resistance to pathogens, reducing disease symptoms and biomass losses. However, the beneficial effects of different arbuscular mycorrhizal (AM) fungal species vary greatly, and the mechanisms behind these differences are not well‐understood. This study investigates varying levels of MIR among AM fungal isolates and their impact on the plant root‐associated metabolome, examining the influence of AM fungi's functional diversity on plant growth, defence, and molecular patterns. Using phenotyping observations, we assessed temporal variation in growth responses of tomato plants inoculated with Rhizoctonia solani and four different AM fungal isolates from the Glomeraceae and Gigasporaceae families, comparing these responses to changes in the root‐associated metabolome. Our results show that most AM fungal isolates enhanced plant growth, with two out of four demonstrating MIR‐effective potential during symbiosis with tomatoes without trade‐offs. The effectiveness of MIR was reflected in variations in metabolomic profiles, with an increase in downregulated metabolomic compounds in effective species. This study enhances understanding of AM fungal species‐specific differences in growth‐related MIR responses in tomatoes and the roles of biochemistry, supporting findings that Glomeraceae species have better MIR abilities. Our results suggest greater MIR‐related biochemical capabilities within Glomeraceae compared to Gigasporaceae. [ABSTRACT FROM AUTHOR]