Skip to main content
CORESTA Congress, Online, 2020, Agronomy/Phytopathology Groups, AP 04

Reduction of cadmium in tobacco leaves

KUDITHIPUDI C.; MORRIS J.W.
Altria Client Services LLC, Product Design and Maintenance, Richmond, VA, U.S.A.

Cadmium is a heavy metal classified as a Class 1 “known human carcinogen” by the International Agency for Research on Cancer (IARC) and is present in both combustible and smokeless tobacco products. Tobacco plants are particularly efficient in accumulating cadmium with most of it being translocated to the leaves. Specialized membrane transport proteins in the form of channels, carriers or pumps mediate the movement of heavy metals through membranes. Heavy metal P-type ATPases (HMAs) are a subgroup of the P-type ATPases super family that contributes to long distance translocation of heavy metals. To reduce tobacco leaf cadmium, a tobacco HMA RNAi construct was introduced into three commercial varieties of different tobacco types, flue-cured, Burley and dark. Control and transgenic lines were produced under controlled greenhouse conditions with and without the addition of cadmium to the medium. These plants were tested for accumulation of cadmium in roots and aerial portions of the plant. Results demonstrated that leaf cadmium reduction varied among selected transgenic plants and ranged from 88 (TN90 06T44) to 91 % (VA359 06T498). Cadmium content in other aerial parts such as bark and pith were also reduced in the range of 72-91 % and 79-92 % respectively. In contrast, root cadmium levels increased up to 20-fold in transgenic plants compared to controls. Results confirmed that the tobacco HMA is involved in root to shoot cadmium transport and disruption of its function reduces cadmium levels in aerial parts of the tobacco plant under experimental conditions.