Comparative proteomic analysis for assessment of the ecological significance of maize and peanut intercropping

Intercropping is an important and sustainable cropping practice in agroecosystems. Peanut/maize intercropping is known to improve the iron (Fe) content of peanuts in calcareous soils. In this study, a proteomic approach was used to uncover the ecological significance of peanut/maize intercropping at the molecular level. We demonstrate that photosynthesis-related proteins accumulated in intercropped peanut leaves, suggesting that the intercropped peanuts had a stronger photosynthetic efficiency. Moreover, stress-response proteins displayed elevated expression levels in both peanut and maize in a monocropping system. This indicated that intercropping contributes to resistance to stress conditions. Allene oxide synthase and 12-oxo-phytodienoic acid reductase, two key enzymes in jasmonate (JA) biosynthesis, increased in abundance in the maize roots of the intercropping system, consistent with the upregulation of JA-induced proteins shown by microarray analysis. These results imply that JA may act as a signaling molecule, playing an important role in intercropping through rhizosphere interaction. This study suggests that peanut/maize intercropping results in high Fe availability in the rhizosphere, leading to variation in the proteins related to carbon and nitrogen metabolism. The advantages of intercropping systems may improve the ecological adaptation of plants to environmental stress.