Transcriptome modulation by endophyte drives rice seedlings response to Pb stress

Area of Science:

• Plant Science
• Environmental Science
• Molecular Biology

Background:

• Heavy metal contamination, particularly lead (Pb), poses a significant threat to agricultural productivity and food safety.
• Endophytic microorganisms can potentially mitigate the adverse effects of heavy metals on plants.
• Understanding the molecular mechanisms underlying plant-microbe interactions under stress is crucial for developing sustainable agricultural practices.

Purpose of the Study:

• To investigate the effects of endophyte inoculation on rice seedling growth and physiological parameters under lead (Pb) stress.
• To analyze the transcriptome-wide gene expression changes in rice seedlings in response to endophyte treatment and Pb stress.
• To elucidate the molecular mechanisms of endophyte-mediated plant tolerance to heavy metal stress.

Main Methods:

• Rice seedlings were subjected to lead (Pb) stress with and without endophyte inoculation for 1 and 5 days.
• Plant growth parameters (plant height, root length) and physiological indicators (SPAD value, chlorophyll fluorescence - Fv/F0, Fv/Fm, PIABS) were measured.
• RNA sequencing (RNA-seq) was performed on rice leaves to identify differentially expressed genes (DEGs).
• Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to annotate DEGs.

Main Results:

• Endophyte inoculation significantly improved plant height, SPAD value, and chlorophyll fluorescence parameters (Fv/F0, Fv/Fm, PIABS) under Pb stress.
• Root length was reduced in endophyte-inoculated seedlings compared to uninoculated ones under Pb stress.
• RNA-seq analysis revealed substantial changes in gene expression, with numerous up-regulated and down-regulated genes involved in photosynthesis, oxidative detoxification, hormone signaling, and transcription regulation.
• A core set of 20 genes showed consistent expression patterns at both 1 and 5 days post-treatment.

Conclusions:

• Endophyte inoculation confers significant physiological and growth benefits to rice seedlings under lead (Pb) stress.
• The transcriptome analysis highlights the involvement of photosynthesis, oxidative stress response, and hormone signaling pathways in endophyte-mediated heavy metal tolerance.
• These findings offer valuable insights into the molecular basis of plant-endophyte interactions under heavy metal stress, with implications for improving crop resilience in contaminated environments.