Bow to the altar, do not bow or genuflect to the tabernacle.
From the liturigical book, “Ceremonial of Bishops”:
“72. A deep bow is made to the altar by all who enter the sanctuary (chancel), leave it, or pass before the altar.”
From the 2002 General Instruction of the Roman Missal (GIRM), n. 274:
During Mass, three genuflections are made by the priest celebrant: namely, after the showing of the host, after the showing of the chalice, and before Communion. Certain specific features to be observed in a concelebrated Mass are noted in their proper place (cf. above, nos. 210-251).
If, however, the tabernacle with the Most Blessed Sacrament is present in the sanctuary, the priest, the deacon, and the other ministers genuflect when they approach the altar and when they depart from it, but not during the celebration of Mass itself.
Otherwise all who pass before the Most Blessed Sacrament genuflect, unless they are moving in procession.
Ministers carrying the processional cross or candles bow their heads instead of genuflecting.
So as I see it, the lector is a minister who should not genuflect “during the celebration of Mass itself”.