Atefeh Mirzaeei - Master of Systematic and Ecological, Natural Science Faculty, Tabriz University, Tabriz, Iran.

Nitrogen-fixing microbial associations with cereals have been of intense interest formore than a century (Roesch et al., Plant Soil ۲۰۰۸;۳۰۲:۹۱ –۱۰۴; Triplett, Plant Soil۱۹۹۶;۱۸۶:۲۹–۳۸; Mus et al., Appl. Environ. Microbiol. ۲۰۱۶;۸۲:۳۶۹۸–۳۷۱۰; Beattyand Good, Science ۲۰۱۱;۳۳۳:۴۱۶–۴۱۷). A recent report demonstrated that an indigenous Sierra Mixe maize landrace, characterized by an extensive development of aerial roots that secrete large amounts of mucilage, can acquire ۲۸–۸۲% of its nitrogen from atmospheric dinitrogen (Van Deynze et al., PLoS Biol. ۲۰۱۸;۱۶: e۲۰۰۶۳۵۲).Although the Sierra Mixe maize landrace is unique in the large quantity of mucilage produced, other cereal crops secrete mucilage from underground and aerial roots and we hypothesize that this may represent a general mechanism for cereals to support associations with microbial diazotrophs. We propose a model for the association ofnitrogen-fixing microbes with maize mucilage and identify the four main functionalities for such a productive diazotrophic association.

Nitrogen-fixing, cereal crops, general mechanism, microbial.