In the photosynthesis apparatus of green plants, the light-harvesting chlorophyll a/b-binding (LHC) proteins serve as antenna for photosystem I and photosystem II. Members of the LHC protein family bind the majority of the photosynthetic pigments (chlorophyll and carotenoids), make the photosynthetic light reaction efficient and regulate the photosynthetic light reaction, for example by dissipating excess light and adjusting excitation balance between the photosystems. A tight regulation of the light reaction is necessary to prevent production of oxygen radicals. We are studying the large family of LHC proteins using biochemical, reverse and forward genetic and molecular biological approaches. In Arabidopsis, 31 genes encode proteins of this family and we are systematically producing and analysing plants that lack different LHC proteins. We have produced a large number of transgenic Arabidopsis lines that each completely lack one of the LHC proteins (by means of anti-sense inhibition), and studies of the photosynthetic performance of these plants help us understand the function of the individual proteins, the structure of the photosystems and energy transfer in the antenna. We are also studying different mutants that are impaired in light harvesting or light dissipation, and have for example identified the protein (PsbS) that work as the safety valve of the photosynthetic light reaction.

 

Jansson, S. () A guide to the LHC genes and their relatives in Arabidopsis. Trends in Plant Sciences 4: 236-240.    Abstract     Full text (pdf)

 

Li, X-P., Björkman, O., Shih, C., Grossman, A.R., Rosenquist, M., Jansson, S. & Niyogi, K.K. () A pigment binding protein essential for regulation of photosynthetic light harvesting. Nature 40: 391-395.   Abstract    Full text (pdf)

 

Andersson, J., Walters, R.G., Horton, P. & Jansson, S. () The photosynthetic antenna proteins CP29 and CP26 are not necessary for protective energy dissipation. Plant Cell 13: .  Abstract   Full text (pdf)

 

Külheim, C., Ågren, J. & Jansson, S. () Rapid regulation of light harvesting and plants fitness in the field. Science 297: 91-93.   Abstract    Full text (pdf)

 

Ruban, A.V., Wentworth, M.,  Yakushevska, A.E., Andersson, J.,  Lee, P.J., Keegstra, W., Dekker, J.P., Boekema, E.J., Jansson, S. & Horton, P. () Plants lacking the main light harvesting complex retain photosystem II macro-organisation. Nature 421: 648-652.

 

Andersson, J., Wentworth, M, Walters, R.G., Howard, C.A., Ruban, A.R., Horton, P. & Jansson, S. () Absence of the Lhcb1 and Lhcb2 proteins of the light-harvesting complex of photosystem II – effects on photosynthsis, grana stacking and fitness. Plant Journal 35: 350-361.

 

 

 

Functional genomics give us tools to look at the total pattern of gene expression in a tissue. We are using DNA microarrays, quantitative RT-PCR and multivariate statistics to study gene expression in leaves of field-grown aspen. The long-term goal of the project is to create tools for understand the total pattern of gene expression in an organism. Particular attention is paid to the process of autumn senescence. We are studying for example gene expression, photosynthesis, metabolism and ultrastructure of the leaves during autumn senescence in order to understand how the process is regulated at the molecular level and finally to be able manipulate it. One tool in the studies is to exploit natural variation in aspen. There is a steep cline in autumn senescence, trees from northern latitudes enter senescence much earlier than those from southern latitudes, and by using dense genetic maps, the complete annotated Populus genome sequence and a collection of natural aspen clones, it will be possible to understand the genetic basis of this, and many other, traits with adaptive significance .

 

Wullschleger, S.D., Jansson, S., & Taylor, G. () Genomics and Forest Biology: Populus Emerges as the Perennial Favorite. Plant Cell 14:

 

Bhalerao, R., Keskitalo, J., Sterky, F., Erlandsson, R., Björkbacka, H., Jonsson Birve, S., Karlsson, J., Gardeström, P., Lundeberg, J., Gustafsson, P. & Jansson, S. (). Gene expression in autumn leaves. Plant Physiology 131: 430-442

 

Wissel, K., Petterson, F., Berglund, A. & Jansson, S. () What affects mRNA levels in leaves of field-grown aspen? – A study of developmental and environmental influences. Plant Physiology 133: .

Andersson, A., Keskitalo, J., Sjödin, A., Bhalerao, R., Sterky, F., Wissel, K., Tandre, K., Aspeborg, H., Moyle, R., Ohmiya, Y., Bhalerao, R., Brunner, A., Gustafsson, P., Karlsson, J., Lundeberg, J., Nilsson, O., Sandberg, G., Strauss, S., Sundberg, B., Uhlén, M., Jansson, S. and Nilsson, P. () A transcriptional timetable of autumn senescence. Genome Biology 5:R24.

Sterky, F., Bhalerao, R., Unneberg, P., Segerman, B., Nilsson, P., Brunner, A., Campaa, L., Jonsson-Lindvall, J., Tandre, K., Strauss, S., Sundberg, B., Gustafsson, P., Uhlén, M., Bhalerao, R., Nilsson, O., Sandberg, G., Karlsson, J., Lundeberg, J. and Jansson, S. () A Populus EST resource for plant functional genomics. Proc. Natl. Acad. Sci. USA, 10./pnas.   Full text