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Plants have Rubisco Activase (Rca) that tells the plant’s energy-producing compound (Rubisco) to start up in sunlight and tells it to stop when the leaf is deprived of light to conserve energy.
Now, scientists are swapping just one 380 molecular building block that forms an Rca in wheat. Doing so will allow you to activate Rubisco faster at higher temperatures.
Elizabete Carmo-Silva, Senior Lecturer at the Lancaster Environment Center who supervised this work for a research project called Realizing Photosynthetic Efficiency Enhancement (RIPE), said: “We took a wheat Rca (2β) that was already good enough to activate Rubisco at lower temperatures and we changed only one of its amino acids for one found in another wheat Rca (1β) that works quite well at higher temperatures but it is rubbish in activating Rubisco, and the result is a new form of 2β Rca that is the best of both worlds. “
Typically, Rca 1β wheat has an amino acid isoleucine, works up to 39 degrees Celsius, but is not great at activating Rubisco. In contrast, the 2β that normally occurs has a methionine amino acid, works up to around 30 degrees Celsius, and is good at acting Rubisco. Here the group has made another variant of 2β with an amino acid isoleucine that works up to 35 degrees Celsius and is very acceptable for activating Rubisco.
Carmo-Silva said: “Essentially, 1β is a junk enzyme and 2β is sensitive to higher temperatures. The good thing here is that we have shown how this amino acid exchange can make Rca active at higher temperatures without actually affecting its efficiency to activate Rubisco, which could help crops initiate photosynthesis under temperature stress to produce higher yields. “
“When you look at the cowpea growing regions in Africa, it stretches from South Africa averaging around 22 degrees Celsius to Nigeria at around 30, and the northernmost areas hit 38. If we can help Rubisco become active in more efficiently at these temperatures, that’s powerful and could help us bridge the gap between yield potential and reality for farmers who depend on these crops for their livelihood. “
RIPE is designing crops to be more productive by improving photosynthesis. They carried out this work in vitro in E. coli. The study is expected to help characterize and improve Rca from other food crops such as cowpea and soybeans, each with multiple different forms of Rca.
RIPE is supported by the Bill and Melinda Gates Foundation, the United States Foundation for Food and Agriculture Research (FFAR) and the UK Government Department for International Development (DFID).
Magazine reference:
- Gustaf E. Degen, an isoleucine residue acts as a thermal switch and regulator in wheat Rubisco activase. DOI: 10.1111 / tpj.14766
