Grafting Cucumber Onto Pumpkin Induced Early Stomatal Closure by Increasing ABA Sensitivity Under Salinity Conditions

Area of Science:

• Plant Physiology
• Molecular Biology
• Agronomy

Background:

• Salt stress induces stomatal closure to prevent water loss.
• Abscisic acid (ABA) signaling is crucial for plant stress responses.
• Grafting is a technique used to improve crop resilience.

Purpose of the Study:

• To investigate the role of pumpkin rootstock in enhancing salt tolerance of cucumber.
• To elucidate the mechanism of ABA signaling in grafted plants under salinity.
• To evaluate the impact of rootstock on ABA biosynthesis and signaling gene expression.

Main Methods:

• Grafting cucumber onto pumpkin rootstock and self-grafted controls.
• Quantification of ABA content in roots, xylem sap, and leaves.
• Analysis of ABA-related gene expression (NCED2, ABCG22, PP2C, SnRK2.1).
• Measurement of stomatal conductance (Gs) and transpiration rate (Tr).

Main Results:

• Cucumber grafted onto pumpkin showed rapid stomatal closure and reduced transpiration under salt stress.
• Increased ABA levels were observed in roots, xylem sap, and leaves of pumpkin-grafted plants.
• Pumpkin rootstock enhanced scion sensitivity to ABA and upregulated key ABA signaling genes.
• Inhibition of root ABA biosynthesis increased transpiration and stomatal conductance.

Conclusions:

• Pumpkin rootstock enhances cucumber's osmotic tolerance to NaCl stress via root-sourced ABA signaling.
• Grafting increases ABA sensitivity in the scion, improving adaptation to saline conditions.
• This grafting strategy offers potential for improving vegetable production in saline environments.