Kevin M. Dorn , CBS 2008
Testing the Causal Effects of Circadian Rhythm on Plant Competitive Ability
Major
Plant Biology and Genetics, Cell Biology & Development
Mentors
Cynthia Weinig, Plant Biology
Brief Bio
When not working, studying, teaching, or sleeping, I enjoy cycling, movies, fine food and drink, and spending time with my girlfriend, Katie.
Future Plans
I will be applying for graduate school where I intend to pursue a PhD in the biological sciences. Following my graduate work, I intend on teaching and doing research at the college level, hopefully in Minnesota so I can be close to my family and friends.
Why Research?
I originally started doing research to earn a little extra money. Incidentally, it would become the best part time job I could ever imagine.
What Did I Get from Research?
I did not expect doing research to completely change my path in life. By getting real world experience in science, I realized that my intended career path wasn’t for me, and I discovered that I could make a living researching something that I truly enjoyed and found incredibly interesting. I’ve also developed quite a lot of patience, concentration, communication skills, as well as a greater overall understanding of science and why it's done.
How Did I Start?
I simply applied for a job posting I saw in a classroom building. My research was initially part of the NSF-REU [National Science Foundation—Research Experience for Undergraduates] internship program, but I’ve also done 2 UROPs, 7 credits of academic credit, and received an hourly wage for a semester in the Weinig lab.
My Advice For Another Student
Just jump right in! I’ve seen too many of my peers say that they are going to look for a research job “next semester”, and it never happens. I think that all undergrads should experience research first hand, and it’s never too early to start. My very first project was spring semester of my freshman year, and it worked out great.
Research Summary
Organisms possess an internal mechanism to keep time, commonly referred to as the circadian clock. Circadian rhythms are regulated by endogenous genetic mechanisms that enable the coordination of physiological and biochemical processes while allowing the anticipation and response to changes in the environment during day-night cycles. In field studies using inbred lines, we observed that circadian period affected competitive responses to crowding. In particular, plants with comparatively short period lengths had significantly longer stem lengths, and these increases in stem length were associated with higher fitness. We were interested in further evaluating whether the observed relationship between period and elongation was causal. To test the effects of circadian rhythm on competitive ability, we grew mutants with 28-hr (ztl-1 and ztl-2 ) or 20-hr (toc1-1 and toc1-2) endogenous periods under 20 and 28 hour exogenous T-cycles (i.e., light:dark cycles of 10:10 and 14:14 respectively). In each T-cycle treatment, plants were subjected to either foliar-shade or neutral-density light treatments that simulate changes in light quality, which occur when plants compete. Plants were censused for stem elongation, petiole elongation, and flowering time. We observed a significant effect of mutant by shade-treatment, in which mutants with a short period (toc1-1 and toc1-2) had greater elongation in response to foliar shade than did the long period mutants. This result suggests that the correlation observed in the field is causal; potentially, individuals with shorter circadian periods pass through the diurnal time when elongation is greatest more frequently than do genotypes with long periods. In addition, we observed that short period mutants delayed flowering relative to wild-type and long-period plants under short T-cycles. This result was confirmed using near isogenic lines, which differ at a single genetic locus.