Interaction of endosperm size factors in maize

Area of Science:

• Plant genetics
• Cytogenetics
• Epigenetics

Background:

• B-A translocations in maize can lead to reduced endosperm size when specific chromosome regions are absent in the male gamete.
• Maternal chromosome duplications typically do not rescue paternal deficiencies affecting endosperm size.

Purpose of the Study:

• Investigate how maternal chromosome segments influence endosperm size when paternal gametes have deficiencies.
• Determine if maternal enhancement of small kernel effects is correlated with paternal small kernel effects.

Main Methods:

• Reciprocal crosses using specific B-A translocations (e.g., TB-4Sa and TB-10L19) in maize.
• Analyzing kernel mass and size phenotypes resulting from different chromosomal combinations.
• Correlating maternal enhancement effects with paternal small kernel effects across various B-A translocations.

Main Results:

• Extra copies of the 4S chromosome segment maternally introduced enhance the small kernel effect of paternal TB-10L19 deficiency.
• Maternal 4S enhancement is observed with paternal TB-1La but not TB-1Sb.
• Maternal enhancement is confined to chromosome regions that cause small kernel effects when present in the male gamete.

Conclusions:

• A dosage-dependent interaction exists between maternal and paternal chromosome segments affecting endosperm size.
• The regions responsible for maternal enhancement of small kernel size are coincident with those causing small kernel effects in males.
• This endosperm dosage effect system may be analogous to aneuploid effects in diploid tissues but with unique triploid endosperm properties.