Structurally Different Exogenic Brassinosteroids Protect Plants under Polymetallic Pollution via Structure-Specific...

Area of Science:

• Plant physiology
• Environmental toxicology
• Agricultural science

Background:

• Heavy metals and aluminum significantly reduce crop productivity in acidic, contaminated soils.
• Brassinosteroids with lactone structures are studied for heavy metal stress, but ketone-containing brassinosteroids remain largely uninvestigated, especially under polymetallic stress.

Purpose of the Study:

• To compare the stress-protective effects of lactone-containing (homobrassinolide) and ketone-containing (homocastasterone) brassinosteroids on barley resistance to polymetallic stress.

Main Methods:

• Barley plants were cultivated hydroponically.
• Brassinosteroids and elevated concentrations of heavy metals (Mn, Ni, Cu, Zn, Cd, Pb) and aluminum were introduced to the nutrient medium.

Main Results:

• Homocastasterone demonstrated greater efficacy than homobrassinolide in mitigating stress impacts on barley growth.
• Both brassinosteroids reduced toxic metal accumulation (excluding Cd) and improved magnesium nutrition under metal stress.
• Homocastasterone uniquely enhanced photosynthetic pigment content, unlike homobrassinolide.

Conclusions:

• Homocastasterone exhibits a more pronounced protective effect against polymetallic stress in barley than homobrassinolide.
• The underlying biological mechanisms driving the differential efficacy of these brassinosteroids require further investigation.