Biology subjects

Martin-Cardoso, H.

Publications and source records attributed to Martin-Cardoso, H..

3 recordsLinked to original sources

bioRxiv2026

Molecular basis of delayed leaf senescence induced by short-term treatment with low phosphate in rice

Leaf senescence is a programmed plant developmental process that can also be regulated by environmental factors, like nutrient availability. Although phosphorus is an essential element determining plants growth and productivity, mechanisms underlying adaptation to phosphorus availability in plants are not well understood. In this study, we combined physiological, biochemical and molecular approaches to investigate the effect of phosphate supply on leaf senescence in rice. We show that short-term treatment of rice seedlings with low phosphate increases photosynthetic pigments content, confers tolerance to methyl viologen-induced oxidative stress in chloroplasts, and increases antioxidant enzyme activities. Leaves from low-Pi-treated plants also showed a reduction in membrane lipid peroxidation and electrolyte leakage. Opposite trends were observed in seedlings under high Pi supply, in which accelerated leaf senescence occurs. Further analyses indicated that CRISPR/Cas9-mediated editing of MIR827, and subsequent reduction in Pi content, promotes delayed leaf senescence, while Pi accumulation in MIR827 or MIR399 overexpressing plants accelerates senescence. These findings strongly support that short treatment with low phosphate delays rice leaf senescence. Transcriptomic analysis demonstrated multiple biological processes underlying adaptation of rice plants to low phosphate, including senescence-associated and metabolic processes. These findings provide novel insights into leaf senescence potentially contributing to sustainable rice production.

plant biology↗

bioRxiv2026

Phosphite, an analog of phosphate, counteracts Phosphate Induced Susceptibility of rice to the blast fungus Magnaporthe oryzae

Phosphate (Pi) and phosphite (Phi), a non-metabolizable analogue of Pi, are taken up by plant roots through the same transport system. Whereas Pi is an essential nutrient for plants, Phi might function as a biostimulant and in protection against pathogens. However, how Phi mechanistically exerts beneficial effects on plants remains unsolved. We examined the impact of Phi and Pi on Arabidopsis thaliana and rice growth and upon pathogen infection. Phi inhibited the in vitro growth of Plectosphaerella cucumerina and Fusarium fujikuroi in a dose-dependent manner, whereas Magnaporthe oryzae growth was largely unaffected. Phis effect on plant growth was dependent on the plant species, the basal Pi level in the plant, and the ratio Pi to Phi. In Arabidopsis, Phi enhanced resistance to P. cucumerina by triggering a hypersensitive response-like cell death. Notably, Phi reversed Pi-induced susceptibility to blast (M. oryzae) and bakanae (F. fujikuroi) diseases in rice. Transcriptomic analysis revealed that Phi triggered extensive reprogramming in rice under high Pi, including the activation of signaling pathways enriched in phosphorylation-dependent processes, while attenuating induction of carbon metabolism. Phi acts as a multifaceted agent, promotes balanced metabolic state, improved plant performance, and reduced Pi-induced disease susceptibility when applied under appropriate Pi conditions. HighlightPhosphite application confers protection against fungal pathogens in Arabidopsis and rice plants by regulating signaling pathways depending on phosphorylation processes.

plant biology↗

bioRxiv2026

Decoding microbial diversity in roots of rice plants under flooded conditions: influence of the host genotype, root compartment and mycorrhizal association

BackgroundThe root microbiome plays a critical role in nutrient acquisition, stress tolerance and overall plant health. Rice, a staple food for more than half of the worlds population, is commonly cultivated under flooded conditions. Despite its agronomical importance, our current understanding of root-associated microbiomes in rice grown under flooded conditions is limited. On the other hand, nitrogen (N) and phosphorus (P) fertilizers are routinely applied to maximize rice yield. It is also well known that root colonization by arbuscular mycorrhizal (AM) fungi enhances mineral nutrition in plants, but whether mycorrhizal associations influence the composition of the rice root microbiome remains poorly understood. In this study, shotgun metagenomic sequencing was used to characterize the root endosphere and rhizosphere microbiomes in two temperate japonica rice varieties (cv. Bomba and JSendra) grown under flooded conditions. The impact of colonization by the AM fungus Rhizophagus irregularis on the root microbiome was investigated. ResultsRoot-associated compartments harbour distinct microbial communities in rice with bacterial taxa comprising approximately 95% of the total microbia in rice roots. At the Phylum level, the root bacteriome was primarily composed of Pseudomonadota (Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria) followed by Actinomycetota. The fungal microbiome was dominated by Ascomycota (Sordariomycetes, Eurotiomycetes and Dothideomycetes) and Basidiomycota. Not only the root compartment, but also the host genotype can shape the root microbiome. Recruitment of specific microorganism mainly occurs at the species level. Genotype-specific and compartment-specific associations of microbial species in mycorrhizal rice roots were also observed supporting that root colonization by an AM fungus contributes to variations in the root microbiome. Further, key microbial species primarily associated to methane production and nutrient cycling (e.g. Phosphate Solubilizing Bacteria and Nitrogen cycling bacteria) colonizing root compartments in each rice genotype and mycorrhizal condition are described. ConclusionsThe rice genotype, root compartment and mycorrhizal condition markedly influence the microbiome in roots of rice plants growing in flooded rice fields. These findings illustrate the potential of the plant to shape its associated root microbiome, thus, offering valuable insights for the development of microbiome-based strategies to improve growth and performance in rice plants under flooded conditions.

microbiology↗