Defining the Optimal Microspore Developmental Window for Efficient Anther-Derived Somatic Embryogenesis in Rubber...

Area of Science:

• Plant Biotechnology
• Plant Breeding
• Somatic Embryogenesis

Background:

• Anther-derived somatic embryogenesis is crucial for rubber tree (Hevea brasiliensis) improvement.
• Microspore developmental stage critically impacts the success of this technique.

Purpose of the Study:

• To correlate visible rubber tree bud characteristics with microspore development.
• To determine the optimal microspore stage for callus induction and somatic embryo formation.
• To identify the origin of embryogenic tissues in anther cultures.

Main Methods:

• Cytological analysis of microspore development in cultivar Reyan 73397.
• In vitro culture of anthers at different developmental stages.
• Histological examination of callus and somatic embryo origins.

Main Results:

• Six microspore developmental phases were identified and linked to bud size (1.42-1.57 mm) and color (green to yellowish-green).
• Anthers with early-uninucleate microspores yielded the highest rates of callus induction and somatic embryogenesis.
• Callus and somatic embryos originated from diploid somatic anther wall tissues, not microspores.

Conclusions:

• The early-uninucleate microspore stage is optimal for rubber tree anther culture.
• A practical method using bud morphology for selecting responsive anthers was developed.
• Understanding the somatic origin of embryogenic tissue enhances anther culture efficiency in rubber tree breeding.