November 13, 2015
Host vector strategy with intracellular symbiotic bacteria
RIKEN CSRS joint research with the Tokyo Institute of Technology has revealed a new chloroplast-controlled mechanism for growth and nutrition response. Researchers clarified that this mechanism evolved into a growth control system following the development of an intracellular symbiotic relationship between the plant host and cyanobacteria (the progenitor of chloroplasts).
Researchers created an Arabidopsis mutant with an enhanced stringent response. They found reduced expression of chloroplast genes and reduced metabolite production. They also determined from smaller chloroplast size that stringent response (which takes place in the chloroplast) controls overall functioning of the chloroplast. When grown in normal conditions, the mutant plants grew to 1.5 times the size of wild-type counterparts. When raised in nutrition-poor conditions, the mutant plants remained green and continued photosynthesizing, while the wild type plants died.
This research clarifies the physiological role of stringent response in plants and should provide a stepping stone for determining whether or not a stringent response exists in animals; it will also propel further investigation into the stringent response and its relationship to the nutrient starvation response.
Nature Plants doi: 10.1038/nplants.2015.167
M. Maekawa, R. Honoki, Y. Ihara, R. Sato, A. Oikawa, Y. Kanno, H. Ohta, M. Seo, K. Saito, S. Masuda,
"Impact of the plastidial stringent response in plant growth and stress responses".
Mitsunori Seo; Unit Leader, Dormancy and Adaptation Research Unit
Kazuki Saito; Group Director
Akira Oikawa; Visiting Scientist, Metabolomics Research Group