Low phosphorus impact on Moso bamboo (Phyllostachys edulis) root morphological polymorphism and expression pattern of the related genes

Abstract Moso bamboo typically grows in phosphorus (P)-deficient soil that limits the growth and development. In this study, ten Moso bamboo genotypes (Ph-1 to Ph-10) were evaluated for their responses to P deficiency during the seedling stage by growing them in both P-sufficient and P-deficient conditions. Adaptive responses to low P conditions were observed in the majority of genotypes. Under P deficiency conditions, total biomass decreased in several genotypes, but at the same time the root-to-shoot ratio (R/S) increased. Principal components analysis identified two main comprehensive traits (PC1 and PC2) related to root volume and surface area and P concentration and accumulation. Based on the analysis, two genotypes (Ph-6 and Ph-10) were identified with significantly different levels of tolerance to P deficiency. The results revealed that the genotype Ph-10 responded to P deficiency by significantly increasing root surface area and volume, while simultaneously reducing the number of root cortex cells when compared to the genotype Ph-6, which showed the lowest tolerance (intolerant). The genotype Ph-10 exhibited a robust response to external low-P conditions, marked by elevated expression levels of PHTs and SPXs. In-situ PCR analysis also revealed distinct tissue-specific expression patterns of the genes in the roots, particularly highlighting differences between Ph-6 and Ph-10. The results provide a foundation for elucidating the mechanism of low-P tolerance, thus potentially contributing to developing high P use efficiency (PUE) in Moso bamboo species.