SEED BIOLOGY
UNDERSTANDING HOW THESE COMPLEX ENTITIES FUNCTION
MENTORS
Prof. Kent J. Bradford
Luckily for me, Kent was interested in the EBM assay I had developed and took me on as a post-doc in his lab in 1995 where his group had used my assay to examine single seed EBM activities prior to the completion of germination. At that time, Kent’s lab was examining genes up-regulated when water-imbibed gib-1 mutant tomato seed were or were not provided with exogenous GA. The fact that the seeds on water germinated up to (but not including) radicle protrusion (the completion of germination) without exogenous GA, had allowed Drs. Peetamber Dahal and Michael Foley to synchronize the seed population to a much greater degree than had been possible previously. After some time elapsed, half the seeds were provided GA, the others not, and the endosperm cap (opposing the radicle), the radicle itself, and the rest of the seed were harvested and mRNA abundances compared using differential cDNA display. I helped follow up some of the candidates identified in this manner. We also examined ABA deficient sitiens tomato mutant seeds for morphological alterations and responses to far-red light. Finally, we started a project on raffinose family oligosaccharides in tomato and maize seeds.
Prof. J. Derek Bewley
I was able to join Derek Bewley’s vibrant lab in 1991 for a PhD in Botany. While I was focused on the seed physiology and anatomy of white spruce (Picea glauca) seeds, many around me were investigating physiological aspects of the embryo’s control of cell wall deterioration of the endosperm during seed germination, whether to weaken it as a barrier to embryo protrusion or to derive nutrients from it. The switch from seed development to germination, usually orchestrated through maturation desiccation in orthodox seeds, was also an area of intense investigation, clarifying the roles of ABA and nutrients in sculpting a desiccation tolerant milieu within the cells. During this time I was fortunate to get to travel to Henk Hilhorst’s lab in Wageningen, The Netherlands, for a four-month stint where we worked on an assay to detect endo-beta-mannanase, an important cell wall modifying enzyme thought to assist the weakening of the megagametophyte in front of the root cap of the conifer embryo, reducing this barrier’s strength to permit subsequent protrusion of the radicle from the seed.
Benjamin Shin-Phin “Ben” Wang, 1927–2017
Ben Wang gave me my first job as a seed scientist at the Canadian National Tree Seed Center at the Petawawa branch of Forestry Canada. For two years I worked with Ben to explore the response to invigoration of tree seeds important to the Canadian commercial forest industry. The physiology of seed dormancy in Black Spruce (Picea mariana) and IDS featured prominently in these endeavors. The influence of high heat (used to extract seeds from the serotinous cones of species such as Jack- and Lodgepole-Pine [Pinus banksiana and P. contorta]) on the survival and vigor of the seeds was a major priority while I was working with Ben.
Prof. Urban Bergsten
During my MS degree Urban was the one who, with his innovative techniques to assist the establishment of conifer seedlings using direct seeding, sparked my interest in seeds and how they function. Various techniques to improve the physiological competence of conifer seeds (leading to more rapid completion of germination and the production of vigorous seedlings; Imbibition, Desiccation Separation (IDS); Invigoration) mitigated the susceptibility of direct seeding techniques to seedbed deterioration and weather play, whether in the nursery or on clear cuts. Additional, physical alterations of the seed bed after site preparation enhanced the seed’s microclimate, enhancing rapid completion of germination. This included generation of pyramidal indentations on site prepared areas and the means by which to mix humus and mineral soil during site preparation to optimize water conducting- and holding-capacity, two attributes positively correlated with successful stand establishment from direct seeding efforts. Urban is currently working on physiological aspects of regeneration as well as technical advances for robotic and smart technology assists in stand establishment.
A. Bruce Downie, Professor 
Department of Horticulture

Laboratory: (859) 218-0799
Office: (859) 257-5237 
Fax: (859) 257-2859
University of Kentucky
Plant Science Building

Laboratory: Room 434
Office: Room 401A
1405 Veterans Dr.
Lexington, KY 40546-0312
 
FOURTH FLOOR LAB LOCATION