Mostly expressed in aerial organs, particularly in expanding leaves, stems, flowers, and siliques. Also present in stipules. In young seedlings, detected in the hypocotyl, cotyledons and rosette leaves,mostly in expanding leaves. At flowering time, expressed in stems, cauline leaves, sepals, and, in open flowers only, in anthers and on stigma surface. Later present in pedicels of developing siliques, nectaries, and along the length of maturing siliques. Expressed in roots during the early stages of lateral root formation. Belongs to the plant proline-rich protein superfamily.