Understanding how organisms adapt to the many challenges they experience in nature is a central goal in biology. Knowledge of the genetic mechanisms underlying adaptation in nature is also useful for increasing crop yields and for the conservation of wild species. One such challenge faced by organisms at high latitudes is freezing temperatures. This research investigates the genetics of freezing tolerance in the mouse-eared cress, a relative of many crop species that has become a "model" organism for which many genetic tools have been developed. In earlier work, the researchers collected seeds of this species from Italy and Sweden and planted them in experimental gardens located in each country. They found that freezing tolerance is required to survive the long, cold winters in Sweden, whereas freezing tolerance reduces performance in Italy. This result exemplifies the concept of biological "trade-offs"; adaptation to one environment often reduces performance elsewhere. This simple principle can explain why there are so many different species on earth, in that each species is adapted to a particular environment. The research investigates the genetic control of freezing tolerance and explores the mechanisms that contribute to the tradeoff in performance across environments. The genetic mechanisms identified in these studies may be useful tools for producing new crop varieties with increased yield in cold climates. In addition, the research team will perform outreach activities that advance scientific literacy and promote careers in science. Michigan State University scientists will contribute to a partnership between K-12 teachers and the W.K. Kellogg Biological Station to develop lesson plans that support Next Generation Science Standards (NGSS) for inquiry based learning.
The research employs cutting edge genetic technologies to address the mechanisms and adaptive value of freezing tolerance using three complementary approaches. First, the genetic basis of freezing tolerance will be further examined in the two original populations in Sweden and Italy using new lines manipulating freezing tolerance genes in otherwise homogeneous parental backgrounds. These lines will then be grown in controlled environment chambers and in the field to estimate the importance of freezing tolerance genes for genetic trade-offs in performance across environments. Second, the genetic basis of freezing tolerance will be investigated in four new populations from Scandinavia and Spain with dramatic differences in freezing tolerance. Third, this research will be expanded to an even broader scale, asking if the same genes for freezing tolerance found in these focal populations are found in other geographic regions. The techniques employed in part three are similar to those used to study the genetics of many human diseases. Taken together, these studies examine the genetic basis of freezing tolerance in a broad diversity of natural populations and assess the mechanisms of performance trade-offs for this important adaptive trait.
