OsZTL1 is involved in phosphate deficiency tolerance and cell wall phosphorus reutilization in rice
Yan Zhou, Yong Qiang Gao, Tian Yi Zhang, Ming Yang Ren, Qi Cheng Lu, Lu Zheng, Ren Fang Shen, Xiao Fang ZhuAbstract
Background and Aims
Limited phosphorus (P) supply severely limits rice growth and productivity, and improving P utilization is important for sustainable crop production. However, the regulatory processes involved in mobilization of P from cell-wall pools remain incompletely understood. Here, we investigated the potential function of OsZTL1 in rice adaptation to P limitation.
Methods
We compared ZH11 with two osztl1 knockout mutants under P-sufficient and P-deficient conditions and examined P status, root cell-wall fractions, pectin-related traits, root NO-related fluorescence, and gene expression. The NO donor sodium nitroprusside (SNP) was used to probe NO-related responses.
Key Results
OsZTL1 transcript abundance progressively increased upon P deprivation in both roots and shoots. Disruption of OsZTL1 improved plant performance during P limitation and was accompanied by increased soluble and total P levels in mutant lines compared with ZH11. During P limitation, osztl1 mutants retained less P in the root cell wall and water-extractable pectin-enriched fraction, together with higher pectin uronic acid content and PME activity and a lower degree of pectin methylesterification. These changes coincided with greater root NO-related fluorescence. SNP treatment largely eliminated genotype differences in soluble P, cell-wall P, pectin-associated P, and pectin uronic acid content. Several phosphate starvation-responsive genes showed altered expression in the mutants, while OsPHR1 and OsPHR2 displayed comparable expression among genotypes.
Conclusions
Our findings suggest a function for OsZTL1 in rice acclimation to P limitation and an association with NO-related changes in root cell-wall P reutilization. The SNP results do not establish that NO acts directly downstream of OsZTL1; genetic evidence is needed to test this relationship.