THE RESPONSES OF WILD-TYPE AND ABA MUTANT ARABIDOPSIS-THALIANA PLANTSTO PHOSPHORUS STARVATION

The growth patterns of plants subjected to phosphorus starvation resem ble those caused by treatment with ABA, suggesting that ABA could medi ate the response of the plant to phosphorus starvation. We examined th e role of ABA in phosphorus stress by comparing growth and biochemical responses of Arabidopsis thaliana ABA mutants aba-l and abi2-1 to tho se of wild-type plants, We first characterized acid phosphatase produc tion of wild-type Arabidopsis in response to phosphorus starvation, We found that several acid phosphatase isozymes are present in roots and shoots, but only a subset of these isozymes are induced by phosphorus stress, and they are induced in both organs, Production of acid phosp hatase in response to phosphorus stress was not affected by the nbn-l or abi2-1 mutations, Low phosphorus also resulted in decreased growth of both wild-type and ABA mutant plants, and the root-to-shoot ratio w as increased in both wild type and mutants, Anthocyanins accumulated i n response to phosphorus stress in both wild-type and mutant plants, b ut the increase was reduced in the aba-l mutant, Thus, two different A BA mutants responded normally in most respects to phosphorus stress, O ur data do not support a major role for ABA in coordinating the phosph orus-stress response.