Lily O'Connor

Program: Plant and Microbial Biosciences

Current advisor: Blake C. Meyers, PhD

Undergraduate university: University of Puget Sound, 2018

Enrollment year: 2020

Research summary

Maize tassels contain thousands of anthers, which produce the male gametophyte, pollen. Fully differentiated pre-meiotic maize anthers are composed of four concentric somatic cell layers that surround the central meiocytes. The tapetal cell layer is the innermost somatic cell layer and the tapetum provides crucial support to the meiocyte through pollen maturation. To support meiocyte and pollen development, tapetal cells become binucleate, secretory, and finally undergo programed cell death. A cascade of four basic helix-loop-helix (bHLH) transcription factors (TF) – Male Sterile (MS) 23, MS32, bHLH122, and bHLH51 – regulate tapetal cell differentiation and development. Mutants in any one of these bHLH TFs results in complete male sterility, due to a failure of the tapetal cell layer to fully differentiate. Ms23, Ms32, and bHLH122 act upstream of and are required to produce 24-nt pre-meiotic phased secondary small interfering RNAs (phasiRNAs). My research focuses on determining how these bHLHs regulate tapetal cell differentiation and development, through their impact on gene expression and chromatin architecture. I am also exploring the role 24-nt phasiRNAs play in tapetal cell development using cell type specific enrichment assays. To explore the function of these TFs and 24-nt phasiRNAs, I have developed a cell type specific marker line using a transgenic epitope tagged version of bHLH122.

Graduate publications
Zhan J, O’Connor L, Marchant DB, Teng C, Walbot V, Meyers BC. 2023 Coexpression network and trans-activation analyses of maize reproductive phasiRNA loci. Plant J, 113(1):160-73. PMCID:

Nan GL, Teng C, Fernandes J, O’Connor L, Meyers BC, Walbot V. 2022 A cascade of bHLH-regulated pathways programs maize anther development. Plant Cell, 34(4):1207-25. PMCID: PMC8972316

Qi M, Berry JC, Veley KM, O’Connor L, Finkel OM, Salas-González I, Kuhs M, Jupe J, Holcomb E, Glavina Del Rio T, Creech C, Liu P, Tringe SG, Dangl JL, Schachtman DP, Bart RS. 2022 Identification of beneficial and detrimental bacteria impacting sorghum responses to drought using multi-scale and multi-system microbiome comparisons. ISME J, 16(8):1957-69. PMCID: PMC9296637