Speaker: Phil Becraft, Iowa State University Department of Genetics, Development and Cell Biology professor

Title: Regulation of maize endosperm development: the NAKED truth

Abstract: Endosperm is the major portion of cereal grains and is of major importance biologically, economically and for food security. Our lab identified several maize genes involved in cell patterning during endosperm development. Normal maize endosperm contains starchy endosperm cells, which are the major storage cells, covered by a single epidermal-like layer of cells called aleurone. Loss of function thick aleurone1 (thk1) mutants have multiple aleurone layers indicating THK1+ functions to restrict the number of aleurone layers. THK1 is a homlog of the NOT1 subunit of the multifunctional CCR4-NOT complex. Double mutants of naked endosperm1 (nkd1) and nkd2 show multiple layers of cells that are not fully differentiated as aleurone showing nkd1;nkd2 are required to restrict the number of aleurone cell layers and to promote aleurone cell differentiation. NKD1 and NKD2 are duplicate, mostly redundant, zinc finger transcription factors. We used comparative transcriptomics of thk1 and nkd1;2 mutants to parse the cell patterning functions from the cell differentiation functions. Both genes appear to regulate cell patterning by controlling functions associated with cell cycle and cell division, while nkd1;2 specifically regulates auxin signaling that is associated with aleurone cell differentiation. NKD1;2 also regulate grain quality traits in starchy endosperm cells and show reciprocal regulatory relationships with OPAQUE2 (O2) encoding a well known bZIP transcription factor involved in regulating storage compound deposition. We used transcriptomics on multiple mutant combinations of nkd1, nkd2 and o2 to reveal unique, overlapping and interacting functions of these genes. During early stages, all 3 genes function primarily in developmental processes, whereas in grain filling stages they interact regulate metabolic processes associated with storage compound deposition. 

Meeting link: https://iastate.webex.com/iastate/j.php?MTID=mb238d165439455f48123c9a3d116aef8

March 30, 2021, GDCB Seminar flyer (Phil Becraft)