... accumulation of citrulline in wild watermelon As a first step to understand the mechanism of citrulline and arginine accumulation in wild watermelon, we focused on the fifth step of citrulline biosynthesis, ... thermotolerance and insensitivity to inhibition by downstream products, citrulline and arginine Results The enzyme involved in catalysis of the fifth step of citrulline biosynthesis in wild watermelon ... ASS, argininosuccinate synthase and ASL, argininosuccinate lyase by arginine [16,17] As a result, the concentration of citrulline and arginine is kept low through these feedback inhibitions in the...