Clusters of cultivated soybean landraces from the North China Plain coordinate root morphology and rhizosheath carboxylates enhancing phosphorus acquisition

Plants have evolved an array of root traits associated with phosphorus (P) acquisition, including morphological and physiological traits. This study aimed to characterize the differences of various root traits in soybean (Glycine max) and explore their roles in P acquisition.

Root functional traits associated with P acquisition were characterized in 49 cultivated soybean landraces from the North China Plain grown in a glasshouse under low-P condition.

We found a large variation in plant growth and all studied root traits. There was a significant correlation between total plant P content and root morphological traits in all 49 varieties. Hierarchical classification on principal components (HCPC) based on principal component analysis (PCA) indicated that soybean varieties could be grouped into three distinct clusters: total plant P content was positively correlated with some root morphological traits and seed P content in cluster 1 and showed positive correlations with root tissue density and rhizosheath carboxylates in cluster 2, while total P content showed no significant correlation with any root trait in cluster 3.

Root morphology and seed P content generally determined P acquisition of the present soybean varieties, but carboxylates also contributed to P uptake in some P-efficient varieties. We may be able to maximize soybean P acquisition via stacking root morphological and physiological traits, thus allowing plants to access different soil P pools.