UK Researchers Finding Ways To Make Crops More Prolific, Saving Farmers Money

By Jordan Strickler

University of Kentucky College of Agriculture, Food and Environment researchers could be onto a big discovery, one that will help crops develop a valuable nutrient for growth, saving farmers from purchasing and applying it themselves. 

Beans, peas and alfalfa, all legume family members, get vital nitrogen by forming a symbiotic, or mutually beneficial, relationship with soil bacteria called rhizobia. This connection leads to the growth of special organs on the roots called nodules. Nodules serve as “factories” where working bacteria convert nitrogen into ammonia the plant can use. However, because sometime the connections are not able to occur, many potential plant-bacterial symbioses don't happen. Scientists believe that understanding more about the genes involved in the process will provide an opportunity to change them, helping bacteria collaborate with a wider spectrum of plants to produce nitrogen.  

UK Department of Plant and Soil Science professor Hongyan Zhu is heading up a team that has found several plant genes that control nodule growth and the conversion of nitrogen to ammonia. Researchers hope the findings will allow for a more efficient symbiotic relationship between rhizobia and crops, leading to more effective production and decreasing the need for additional nitrogen to be purchased and applied. 

The Proceedings of the National Academy of Sciences of the United States of America published the team’s recent study, in which they cloned a pair of receptors from the legume Medicago truncatula. The plant is a small annual legume native to the Mediterranean region, closely related to alfalfa, with receptors that stop a wide range of possible bacterial partners from making nodules. The team discovered a gene in bacteria needed to turn on this receptor-mediated restriction of nodulation, allowing for a way to control the symbiotic relationships between bacteria and their hosts.  

“Nodulation capacity and nitrogen fixation efficiency can vary tremendously between different plant-bacterial partnerships,” Zhu said. “So, what we want to do is to help plants find their best microbial partners to maximize the potential of symbiotic nitrogen fixation, thus reducing the need for nitrogen input in the fields. Such knowledge could also contribute to engineering non-legumes such as cereal crops to acquire the ability to form symbiotic interactions with nitrogen-fixing rhizobia."  

Collaborators from the Plant Biology Institute of Hungary contributed to the study.   

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2014-67013-21573 and by the U.S. Department of Agriculture, Agricultural Research Service under Agreement No. 5850428003. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.   

Research reported in this publication was supported by the National Science Foundation under Award Number 1758037. The opinions, findings, and conclusions or recommendations expressed are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.