Black Rot Disease Decreases Young Brassica oleracea Plants’ Biomass but Has No Effect in Adult Plants

Abstract

Black rot disease, caused by the bacterium Xanthomonas campestris pv. campestris (Pammel) Dowson (Xcc), causes important yield losses in Brassica oleracea L. crops worldwide. In temperate areas, yield losses are mostly due to the discarding of those plants showing chlorotic and necrotic lesions, since they may be unmarketable. However, the biomass loss caused by the diversion of resources from the primary to the secondary defense metabolism could also affect the final crop yield. In this work, we have focused on studying the impact of Xcc race 1 invasion on the biomass production of young and adult B. oleracea plants. The results have shown that Xcc infection reduces biomass and photosynthesis in the aerial parts of seedlings and modifies their water percentage in a time-dependent manner. When adult plants were inoculated in the field, no effect was detected on the leaves or the biomass of marketable products. This was probably due to a better immune response when compared to seedlings. Since the first developmental stages of B. oleracea crops are especially vulnerable to Xcc, plant disease control should be increased in order to avoid yield losses of marketable products at the adult stage.