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

Moso bamboo typically grows in phosphorus (P)-deficient soil that limits its growth and development. In this study, 10 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 (LP) conditions were observed in the majority of genotypes. Under P deficiency conditions, the total biomass decreased in several genotypes, but at the same time, the root-to-shoot ratio increased. Principal component analysis identified two main comprehensive traits (PC1 and PC2) related to the 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 the root surface area and volume, while simultaneously reducing the number of root cortex cells when compared with the genotype Ph-6, which showed the lowest tolerance (intolerant). The genotype Ph-10 exhibited a robust response to external LP conditions, marked by elevated expression levels of PHOSPHATE TRANSPORTERs and SYG1/PHO81/XPR1s. In situ Polymerase Chain Reaction (PCR) analysis also revealed distinct tissue-specific expression patterns of the genes in the roots, particularly highlighting the differences between Ph-6 and Ph-10. The results provide a foundation for elucidating the mechanism of LP tolerance, thus potentially contributing to developing high P-use efficiency in Moso bamboo species.