Cotton plants get a potassium boost from two teamwork hormones
A new study reveals how jasmonate and ethylene work together to activate a key K+ transporter in cotton, improving low-K⁺ tolerance and seed cotton yield.
Potassium (K⁺) is an essential macronutrient that plays critical roles in diverse physiological processes in plants, including photosynthesis, enzyme activation, and osmoregulation. However, over 70% of global cultivated soils are affected by K⁺ deficiency, posing a widespread challenge for agriculture, particularly for crops with high K⁺ demands such as cotton.
A research team led by Professors Zhaohu Li and Xiaoli Tian at China Agricultural University has identified a hormone-driven molecular cascade that enhances K⁺ uptake in cotton under low-K⁺ conditions. The findings were published in Science Bulletin in an article titled, “GhZAT10 integrates jasmonic acid and ethylene pathways to synergistically regulate the GhKUP3aD-mediated high-affinity K⁺ uptake in Gossypium hirsutum”.
In this study, researchers identified GhKUP3aD as a pivotal high-affinity K⁺ transporter in cotton. Functional analyses confirmed that GhKUP3aD is essential for maintaining K⁺ homeostasis under low-K⁺ stress. Furthermore, the C2H2-type zinc-finger transcription factor GhZAT10 directly binds to the GhKUP3aD promoter, functioning as its transcriptional activator.
A central mechanism revealed in the study is that the GhZAT10-GhKUP3aD module is synergistically regulated by the jasmonate (JA) and ethylene signaling pathways. Downstream components of these pathways—GhMYC2s (JA) and GhEIN3dD (ethylene)—directly bind to the GhZAT10 promoter to enhance its expression. Crucially, these two proteins physically interact to form a transcriptional complex that synergistically amplifies GhZAT10 activation beyond their individual effects.
The study also reveals a layered repression mechanism that operates when K⁺ supply is adequate. Under K⁺-sufficient conditions, the JA signaling repressors GhJAZ2 and GhJAZ10 sequester both GhMYC2s and GhZAT10, thereby suppressing the pathway and preventing unnecessary metabolic expenditure when enhanced K⁺ uptake is not required.
To translate these molecular findings into agricultural practice, the team conducted field experiments under moderate-to-severe soil K⁺ deficiency (available K⁺ levels below 60 mg kg⁻¹). Foliar application of methyl jasmonate (MeJA) or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) improved leaf K⁺ concentration and photosynthetic performance in cotton, and their combined application had the best effect, increasing seed cotton yield by 11.6%.
This research delineates the GhMYC2s-GhEIN3dD-GhZAT10-GhKUP3aD regulatory axis, providing a mechanistic basis for hormonal crosstalk underlying cotton K⁺ uptake. These findings deepen our understanding of potassium uptake mechanisms in crops and provide a new strategy for improving potassium use efficiency in agricultural production.
Journal
Science Bulletin
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