Among the halakhot presented in our Mishna, Rabbi Yose and Rabbi Shimon teach that a woman who marries an androgynous kohen will be permitted to eat teruma, i.e. that we view the marriage as a legitimate one, even though the status of an androgynous – who has both male and female sexual organs – as a man who can marry is questionable.
Given the questionable status of this marriage, the Gemara searches for an explanation of this ruling. One suggestion that is made is that we only permit her to eat teruma d’rabbanan – produce that is only considered teruma on a Rabbinic level – since teruma in our day-and-age is only a Rabbinic mitzva.
The question as to whether teruma in the contemporary world is a Biblical obligation or only a Rabbinic one is an argument that dates back to the time of the Mishna and continues through the time of the amora’im and the rishonim. According to some, the basis for the opinion that teruma today is only Rabbinic in nature stems from the position that there is no longer any holiness to the Land of Israel on a Biblical level, and that all mitzvot connected with the land are kept today only on a “voluntary” basis, i.e. based on the agreement of the Sages. In truth, this position depends less on the status of the Temple, and more on the question of whether rov yisrael yoshvim al admatam – does the majority of the Jewish people dwell in the Land of Israel.
According to this approach, even during the period of the Second Temple, the returnees to Israel from the exile kept the mitzvot ha-teluyot ba-aretz – the agricultural commandments connected to the Land of Israel – only on a Rabbinic level. This, in fact, is the position of the Rambam. According to this, it was the Jewish people, upon their return to the land, who accepted these mitzvot on themselves voluntarily – see Nehemiah 9-10 for a picture of the situation at that time, and the people’s willingness to participate in these commandments.