Large-scale evaluation of aluminum tolerance in maize ( Zea mays L.) acessions

Germplasm screening is essential to effectively understand the mechanisms underlying aluminum (Al) toxicity, hence guide breeding strategies for alleviating the decline in crop productivity. This study screened a large population of 481 maize acessions by measuring eight net root traits, two biomass traits, and three Al concentration traits of seedlings in hydroponic cultures under Al stress. Aluminum stress significantly restrained the plant biomass and root growth. Meanwhile, genetic correlation analysis indicated that biomass traits were significantly correlated with net root traits in the presence or absence of Al treatment. The relative traits exhibited similar results; Al tolerance coefficient (ATC) of biomass traits and ATC of net root traits. Using principal component analysis (PCA), all maize acessions were classified as tolerant, meso-tolerant, or sensitive to Al stress according to Al tolerance index (ATI). The acessions were further categorized under high-performance, low-performance, or moderate-performance groups according to Al tolerance performance index (API). Subsequently, ATI and API defined seven Al-tolerant acessions with high performance and four Al-sensitive acessions with low performance. This large-scale evaluation of Al tolerance identified high-quality Al-tolerance maize acessions, hence providing vital information for further genetic analyses and breeding of maize for Al tolerance.