Phenotypic and Transcriptional Analysis of Divergently Selected Maize Populations Reveals the Role of Developmental Timing in Seed Size Determination

Authors

Rajandeep Sekhon, University of Wisconsin
Candice Hirsch, University of Wisconsin - Madison
Kevin L. Childs, Michigan State UniversityFollow
Matthew Breitzman, University of Wisconsin
Paul Kell, University of Wisconsin
Susan Duvick, USDA
Edgar Spalding, University of Wisconsin
C. Robin Buell, Michigan State University
Natalia de Leon, University of Wisconsin
Shawn Kaeppler, University of WisconsinFollow

Date of this Version

2014

Citation

Plant Physiology, June 2014, Vol. 165, pp. 658–669

Comments

This article is a U.S. government work, and is not subject to copyright in the United States.

Abstract

Seed size is a component of grain yield and an important trait in crop domestication. To understand the mechanisms governing seed size in maize (Zea mays), we examined transcriptional and developmental changes during seed development in populations divergently selected for large and small seed size from Krug, a yellow dent maize cultivar. After 30 cycles of selection, seeds of the large seed population (KLS30) have a 4.7-fold greater weight and a 2.6-fold larger size compared with the small seed population (KSS30). Patterns of seed weight accumulation from the time of pollination through 30 d of grain filling showed an earlier onset, slower rate, and earlier termination of grain filling in KSS30 relative to KLS30. This was further supported by transcriptome patterns in seeds from the populations and derived inbreds. Although the onset of key genes was earlier in small seeds, similar maximum transcription levels were observed in large seeds at later stages, suggesting that functionally weaker alleles, rather than transcript abundance, may be the basis of the slow rate of seed filling in KSS30. Gene coexpression networks identified several known genes controlling cellularization and proliferation as well as novel genes that will be useful candidates for biotechnological approaches aimed at altering seed size in maize and other cereals.