Evaluation of fertilization and flower abscission following over-expression of an apple NAK-type protein kinase in tomato

Abstract

The Ser/Thr protein kinase subfamily of the novel Arabidopsis protein kinase (NAK) family is unique to plants and is not found in animals or prokaryotes, suggesting that NAKs play specific signalling roles in the control of plant growth and development. However, little is known about the function of NAK-type protein kinases. Here, we used a transgenic tomato plant system to examine the biological functions of AFSK, a NAK-type protein kinase isolated from apple fruits. Gain-of-function transgenic tomato plants containing the AFSK gene were developed by Agrobacterium-mediated transformation and plant regeneration. The plants had normal flower phenotype with respect to their overall shapes and sizes. However, the plants displayed decreased self-fertilization and early flower drop at the floral abscission zone following petal loss. These results suggest that AFSK affects pollen development and promotes floral abscission.