The role of OsNLA1 in regulating arsenate uptake and tolerance in rice.

Arsenic (As) contamination in agricultural soil can cause phytotoxicity and lead to As accumulation in crops. Rice (Oryza sativa) feeds half of the world's population, but the molecular mechanism of As detoxification is not well understood in rice. In this study, the role of OsNLA1 in arsenate uptake and tolerance in rice was analyzed. OsNLA1 expression was induced in response to As(V) stress. The osnla1 mutant was more sensitive to As(V) stress than those of the wild type (WT). When exposed to As(V), mutation of OsNLA1 resulted in 30% greater As accumulation in roots and shoots of the WT. Although OsPT8 expression was induced after As(V) exposure, the amount of its protein was reduced. Unexpectedly, the osnla1 mutant showed a significant increase in punctate structures of OsPT8-GFP in response to As(V) stress, while the amount of the OsPT8-GFP protein in the osnla1 mutant was greater than in the WT. Combining OsNLA1 mutation with OsPT8 overexpression resulted in As(V) hypersensitivity, As hyperaccumulation, and higher shoot to root ratio of As in rice. These results indicated that OsNLA1 plays an important role in arsenate uptake and tolerance, mainly via regulating the amount of Pi transporters.