Comparative transcriptome profiling of potassium starvation responsiveness in two contrasting watermelon genotypes

Area of Science:

• Plant Physiology
• Molecular Biology
• Agronomy

Background:

• Potassium (K⁺) is crucial for crop yield and quality, with deficiency significantly impacting production.
• Watermelon (Citrullus lanatus) is economically vital but susceptible to K⁺ deficiency.
• Understanding K⁺ deficiency tolerance mechanisms is key to improving crop K efficiency.

Purpose of the Study:

• To investigate the molecular mechanisms of K⁺ deficiency tolerance in contrasting watermelon genotypes.
• To compare the root transcriptome responses to K⁺ deficiency in K-efficient (YS) and K-inefficient (8424) watermelon.

Main Methods:

• Comparative analysis of two watermelon genotypes (YS and 8424) under K⁺ deficiency.
• Illumina RNA sequencing of root transcriptomes at 6 and 120 hours after treatment (HAT).
• Analysis of gene expression related to K⁺ uptake, stress responses, and signaling pathways.

Main Results:

• The K-efficient genotype YS exhibited less inhibited root growth and repressed stress-related gene expression compared to 8424.
• YS showed reduced induction of genes involved in jasmonic acid, reactive oxygen species, Ca²⁺ signaling, and lignin biosynthesis.
• 8424 displayed significant induction of these stress-related genes under K⁺ deficiency.
• Distinct short-term and long-term gene regulation mechanisms for root K⁺-uptake were observed.

Conclusions:

• Repressed defense and stress responses in YS conserve energy, promoting root growth and enhancing K⁺ uptake and tolerance.
• This study provides the first global root transcriptome data for watermelon under K⁺ deficiency.
• Findings offer novel insights into molecular mechanisms of K⁺ deficiency tolerance in K-efficient genotypes, valuable for crop improvement.