Genetic approach for achieving ultra low nicotine content in tobacco

A method of curing one or more leaves of a Nicotiana plant comprising:

• (A) a modification that reduces the activity of BBLa, BBLb, and BBLc or reduces expression of a nucleic acid encoding BBLa, a nucleic acid encoding BBLb, and a nucleic acid encoding BBLc;
• and
• (B) a homozygous recessive allele of nic1 or a homozygous recessive allele of nic1 and a homozygous recessive allele of nic2,
• the method comprising:
• (a) a yellowing process comprising heating the leaf at a temperature starting at 92° F.-96° F. and increasing to a temperature of 104° F.-108° F. at a rate of about 1° F. per hour until reaching a maximum upper temperature and holding at the upper temperature for a period of about 52-58 hours;
• (b) a leaf drying process comprising drying at a temperature of about 120° F. for about 22 hours;
• and
• (c) a stem drying process comprising drying at a temperature of about 132° F.-138° F. for about 50 hours to about 65 hours,
• thereby curing the one or more leaves of the Nicotiana plant and producing one or more cured leaves of the Nicotiana plant.