Fused lobed anther and hooked stigma affect pollination, fertilization and fruit set in mango: a scanning electron...

Area of Science:

• Plant Pathology
• Reproductive Biology
• Horticulture

Background:

• Mango malformation disease significantly reduces global mango production.
• The exact cause and agents of mango malformation have been debated, with Fusarium species implicated.
• Elevated endogenous ethylene levels are suspected to alter reproductive organ morphology under stress.

Purpose of the Study:

• To investigate the functional morphology of healthy and malformed mango reproductive organs using scanning electron microscopy (SEM).
• To identify morphological differences in anthers and stigmas between healthy and diseased mango flowers.
• To elucidate the role of these morphological changes in reproductive failure.

Main Methods:

• Scanning electron microscopy (SEM) was employed to examine the ultra-structure of reproductive organs in healthy and malformed mango flowers (cv. Baramasi).
• Comparative analysis of anther and stigma morphology was conducted.
• Pollen viability and stigmatic receptivity were inferred from morphological observations.

Main Results:

• Healthy anthers were bilobed with abundant pollen; malformed anthers showed fused lobes and few deformed pollen grains.
• Healthy stigmas had a broad surface; malformed stigmas presented a hooked, pointed tip.
• These morphological defects in male and female reproductive organs lead to failed sexual reproduction by inhibiting pollen germination and growth.

Conclusions:

• Fused anthers with impaired pollen and hooked stigmas with poor receptivity are primary causes of reproductive failure in mango malformation.
• Abnormal floral development is likely induced by endogenous stress ethylene, potentially exacerbated by cyanide, leading to necrosis and desiccation.