Effect on wheat root development of inoculation with an Azospirillum brasilense mutant with altered indole-3-acetic acid production.

To evaluate the involvement of indole-3-acetic acid (IAA) in promotion of root development, the effects of inoculation of wheat seedlings with Azospirillum brasilense SpM7918, a very low-IAA producer, were estimated. Compared with the wild-type strain Sp6, SpM7918 showed a reduced ability to promote root system development in terms both of number and length of lateral roots and of distribution of root hairs.