Que tal Afonso, tuve que recurrir a mi libro de fisiología, aquí la respuesta :

Auxin-induced ethylene production.

In some instances, auxins and ethylene can cause similar plant responses, such as induction of flowering in pineapple (PIÑA) and inhibition of stem elongation. These responses might be due to the ability of auxins to promote ethylene synthesis by enhancing ACC synthase activity. These observations suggest that some responses previously attributed to auxin (indole-3-acetic acid, or IAA) are in fact mediated by the ethylene produced in response to auxin. Inhibitors of protein synthesis block both ACC and IAA-induced ethylene synthesis, indicating that the synthesis of new ACC synthase protein caused by auxins brings about the marked increase in ethylene production. Several ACC synthase genes have been identified whose transcription is elevated following application of exogenous IAA, suggesting that increased transcription is at least partly responsible for the increased ethylene production observed in response to auxin (Nakagawa et al.1991; Liang et al. 1992).

Saludos,

Carlos Castañeda.