The precise regulation of plant growth opens up the potential to optimize crops in terms of economic efficiency in cultivation and harvesting.
In tobacco field cultivation, so-called topping – the removal of the shoot apical meristem – is common agronomical practice. However, this stimulates the undesirable growth of new shoots (suckers) from the axillary buds at the leaf base. When such suckers grow, valuable plant resources are reallocated to axillary buds thereby reducing yield and quality of the main leaves. Therefore, after topping, axillary buds are chemically treated to inhibit their outgrowth. This chemical control is done by hand, making it time-consuming and expensive. The harmful chemicals may persist after leaf processing and can reduce product quality. Plants with inhibited or delayed growth of axillary buds would therefore significantly improve cultivation, harvesting and product quality.
In our work, we identified a regulatory axillary-specific element using modern molecular biological methods, and the targeted modification increased its activity after topping. For proof-of-concept, we expressed a growth inhibitory gene - a bacterial RNAse - in a tissue-specific manner in the axillary meristems of tobacco plants. This significantly delayed the formation of axillary shoots before as well as their outgrowth after topping. In this way, the number of axillary shoots after topping could be significantly reduced not only in the greenhouse but also under natural conditions in the field.
Our results add an important element to the body of knowledge on the control of axillary branching in plants and will contribute in the future to reduce the labor input as well as the use of chemicals for the removal of axillary shoots in field cultivation.