Male gametes and fertilization in angiosperms.

Area of Science:

• Plant reproductive biology
• Angiosperm reproduction
• Cell biology

Background:

• Double fertilization in angiosperms is linked to accelerated reproduction.
• The male gametophyte undergoes significant evolutionary changes.
• Understanding the mechanisms of sperm-egg interaction is crucial.

Purpose of the Study:

• To review the evolution of the angiosperm male gametophyte and double fertilization.
• To explore the cellular and molecular aspects of generative and sperm cells.
• To discuss hypotheses regarding sperm cell involvement in fertilization.

Main Methods:

• Review of existing literature on angiosperm male gametophyte and double fertilization.
• Analysis of cellular structures, including microtubular and actin microfilament organization.
• Investigation of intermediate-filament-like systems (IFS) using monoclonal antibodies.
• Examination of sperm cell dimorphism and surface antigens.
• Consideration of molecular data, including translatable mRNA pools.

Main Results:

• Generative cells show similarities to animal cells during mitosis, with altered microtubular organization post-isolation.
• Actin microfilaments and two types of IFS are present in generative cells, with IFS found in the vegetative nucleus.
• Evidence supports directed fertilization over random chance, including sperm cell dimorphism and specific surface antigens.
• Translatable mRNA pools in generative and sperm cells offer potential for identifying male gamete-specific genes.

Conclusions:

• Evolution of double fertilization involved reduced mitoses and the male germ unit.
• Cellular and molecular evidence supports directed fertilization, challenging the chance hypothesis.
• Further research using molecular techniques can elucidate male gamete-specific gene functions.