Interspecific facilitation between intercropped millets and peanuts: insights from root proteomics analysis

Intercropping is practised globally because of its advantages in terms of productivity and resource use efficiency. However, our knowledge on the molecular mechanisms underlying belowground interspecific interactions in intercropping systems is still very limited. Pot experiments involving both intercropped millet and peanut were conducted to quantify the differentially expressed proteins in each component crop under conditions of complete, partial and no interspecific interactions based on tandem mass tag (TMT) labelling. The results showed that the yields of both crops in the intercropping system increased in response to complete root interactions due to increases in nutrient acquisition as well as increases in root length and surface area. There were 73 differentially expressed proteins in the millet roots and 41 in the peanut roots, most of which were involved in C metabolism, N metabolism, transport and signal transduction. Additional bioinformatic analyses revealed that root interactions improved N and P assimilation via relatively high amounts of proteins such as urease and inorganic phosphate transporter in the millet roots and malate dehydrogenase increased P assimilation related proteins in the peanut roots. These results would contribute to a comprehensive understanding at molecular level in cereal/legume intercropping systems in response to interspecific root interactions.