The mac1 gene: controlling the commitment to the meiotic pathway in maize

Area of Science:

• Plant developmental biology
• Genetics and genomics
• Reproductive biology

Background:

• Flowering plant development involves a switch from vegetative to reproductive pathways.
• Subepidermal cells in ovules and anthers commit to meiosis, forming archesporial cells.
• Archesporial cells differentiate into megasporocytes and microsporocytes, crucial for reproduction.

Purpose of the Study:

• To investigate the genetic control of the vegetative to meiotic transition in maize ovule development.
• To characterize a novel mutation affecting archesporial cell development.
• To understand the role of the identified gene in female gametophyte formation.

Main Methods:

• Isolation and characterization of a recessive pleiotropic mutation, multiple archesporial cells1 (mac1).
• Cytological analysis of maize ovule development in wild-type and mutant plants.
• Genetic mapping of the mac1 mutation to chromosome 10 short arm.

Main Results:

• The mac1 mutation causes multiple hypodermal cells to develop into archesporial cells in maize ovules.
• Mutant megasporocytes undergo normal meiosis, but multiple embryo sacs form per ovule.
• Abnormal megaspore differentiation and embryo sac formation lead to partial plant sterility.

Conclusions:

• The MAC1 locus is essential for regulating the number of archesporial cells during maize ovule development.
• Sporophytic expression of MAC1 is critical for normal female gametophyte development.
• The mac1 mutation provides insights into the genetic regulation of reproductive pathway commitment in plants.