Constitutive BoHAK5 expression and early robust induction of salicylic acid biosynthesis genes as candidates to explain the tolerance of broccoli to limiting potassium

Potassium is vital for optimum plant growth and crop yield and so is an important component of fertilizers. However, our knowledge of the physiological and molecular response in response to limiting potassium conditions is incomplete. Here we performed a detailed transcriptomic analysis of the model plant, Arabidopsis and the crop plant, broccoli to compare and contrast the response to this abiotic stress. Our results show that broccoli plants lose potassium at a much slower rate than Arabidopsis. This may be explained by the high levels of expression of the BoHAK5 gene. Both Arabidopsis and broccoli showed characteristic responses observed in other plant species, related to oxidative stress and hypoxia and jasmonic, salicylic and abscisic acid signaling. In broccoli, we also observed alterations in the gene expression patterns of enzymes and in the levels of intermediates involved in the biosynthesis of glucosinolates, which are important molecules contributing to the added nutritional value of broccoli. Lastly, we provide evidence for concomitant alterations in the transport of several other ions, such as iron, phosphate and nitrate. Our data help to characterize the response of broccoli to limiting potassium conditions and may provide insights for the development of varieties of broccoli with reduced fertilization requirements. Overall design: Transcriptomic response in roots and leaf in broccoli after 1, 3 and 6 days