oxysporum f. sp. chrysanthemi can be distinguished as three physiological races on the basis of their pathogenicity to the panel of differential cultivars. Sequencing of the intergenic spacer (IGS) region of ribosomal DNA (rDNA) and phylogenetic analysis showed that the Fusarium races fell into three phylogenetic groups, which coincided with those observed in pathogenicity tests. Analysis of the IGS sequences revealed a
high degree of similarity among strains from Italy and Spain from different host species, suggesting that recent outbreaks in these ornamentals were probably caused by introduction of infected nursery material from a common origin. ”
“To cope with the challenge of pathogens, plants have evolved a wide variety of resistance mechanisms that rely both on constitutive and on inducible defences. Systemic acquired resistance (SAR), a form of inducible resistance that occurs following an earlier localized exposure to a pathogen, provides a long-lasting PLX4032 ic50 systemic immunity against
a wide range of pathogens in plants. The great benefits of SAR lead to its practical use in agriculture for plant disease management. Pepper (Capsicum annuum) is one of the economically important RXDX-106 research buy crops growing worldwide, and in this review, we summarize the scientific research-based studies of SAR in pepper during the past decades. Effects of various exogenous inducers of SAR, such as salicylic acid, 上海皓元 DL-β-amino-n-butyric acid, benzothiadiazols and avirulent pathogens on pepper plants have been extensively investigated by different research groups. Biochemical and molecular studies of SAR phenomena also revealed the involvement of radical burst, cell death, endogenous hormonal signalling and defence-related gene expression during SAR establishment in pepper. New knowledge and understanding emerging from the pepper SAR studies will allow the development of novel approaches to enhance the durable resistance of pepper to pathogens, thereby helping to secure the future supply of safe and nutritious pepper worldwide. ”
“Zucchini
yellow mosaic virus (ZYMV), Papaya ringspot virus – type W (PRSV-W) and Zucchini lethal chlorosis virus (ZLCV) cause important diseases on zucchini squash crops in Brazil. ZYMV and PRSV-W belong to the genus Potyvirus and are transmitted by aphids, whereas ZLCV belongs to Tospovirus and is transmitted by the thrips Frankliniella zucchini. These three viruses may occur simultaneously in the field, and the epidemiology of the corresponding diseases may be determined by interactions among viruses, hosts and vectors. In this work, the progress of the diseases caused by these viruses was studied over a temporal and geographic range for three planting seasons (PS). For the lethal chlorosis (ZLCV), a monomolecular model was found to be the best fit for the data, though only during the third PS. For data collected during the first two PS, the Gompertz model was found to fit the data best.