CaLhcb1-like coordinates ROS dynamics and lignin accumulation to gate Ralstonia solanacearum resistance in pepper...

Area of Science:

• Plant Biology
• Molecular Plant Pathology
• Biochemistry

Background:

• Chloroplasts are key players in plant-pathogen interactions, influencing reactive oxygen species (ROS) homeostasis, photosystem II (PSII) function, and spectral signatures.
• Light-harvesting complex II (LHCII) proteins are involved in photosynthesis and have emerging roles in plant defense.

Purpose of the Study:

• To investigate the role of the CaLhcb1-like gene in pepper (Capsicum annuum) resistance to Ralstonia solanacearum.
• To understand the molecular mechanisms by which CaLhcb1-like affects plant defense responses.

Main Methods:

• Comparative transcriptomics to analyze CaLhcb1-like expression in resistant and susceptible pepper cultivars.
• Virus-induced gene silencing (VIGS) to knock down CaLhcb1-like expression.
• Subcellular localization, spectral reflectance measurements, PSII activity assays, ROS quantification, gene expression analysis, and biochemical assays (peroxidase activity, lignin quantification).

Main Results:

• CaLhcb1-like expression is genotype-specific and targets chloroplasts.
• Knockdown of CaLhcb1-like enhanced resistance to bacterial wilt, reducing spectral changes in the 400-690 nm range.
• Silenced lines showed altered PSII parameters, biphasic ROS dynamics, and increased expression of defense-related genes.
• Biochemical assays confirmed increased peroxidase activity and lignin accumulation in CaLhcb1-like silenced pepper plants.

Conclusions:

• CaLhcb1-like negatively regulates pepper defense responses against Ralstonia solanacearum.
• The gene impacts ROS homeostasis and lignin accumulation, linking spectral variations to disease progression.
• CaLhcb1-like represents a potential target for enhancing crop disease resistance.