Journal of Plant Pathology最新文献

Fire blight is a devastating disease of apple and pear worldwide. One reason fire blight is so difficult to manage is because of the lack of effective non-antibiotic management options as well as a limited host resistance gene pool. Traditional management approaches utilizing antibiotic and copper sprays face multiple problems including antibiotic resistance and human health concerns. Furthermore, most management materials are used to control the blossom blight stage of infection, and fewer materials are available to control shoot blight stage of infection. Breeding for host resistance against fire blight is limited by the heterozygosity of apple, as well as the lack of understanding of the host-pathogen interactions. In this review, we raised some of these “burning questions”, which suggest directions for future research in management and resistance breeding of fire blight.

Ralstonia solanacearum and R. pseudosolanacearum are well-known bacterial plant pathogens that cause significant losses to both ornamental and agricultural plants. It has been suggested that they are not the primary cause of bacterial wilt in Eucalyptus species, but rather are opportunistic, taking advantage of trees predisposed to infection by abiotic and biotic factors. To test this hypothesis, the bacterial community within the vascular tissue of asymptomatic Eucalyptus grandis x E. urophylla trees, and those displaying varying stages of infection in China and Indonesia were compared using 16S rRNA profiling. Asymptomatic trees growing in areas where bacterial infections had never previously been reported to occur were included as controls. Ralstonia species were found within the vascular tissue of both asymptomatic and symptomatic trees, in high abundance. In the control samples, bacterial diversity within the vascular tissue was high with a low abundance of Ralstonia species. The presence of Ralstonia species in asymptomatic and control samples supports the hypothesis that these species are latent and/or opportunistic pathogens in E. grandis x E. urophylla trees.

Tamarix and Haloxylon species are considered important trees in the desert regions. During a survey conducted on Tamarix and Haloxylon trunk diseases in Iran, numerous Botryosphaeriaceae isolates were recovered from infected wood tissues of trees showing dieback and canker symptoms. Our study aimed to identify and evaluate the pathogenicity of these isolates. Based on cultural characteristics, microscopic morphological features and phylogenetic analyses of the internal transcribed spacer (ITS) and partial large subunit (LSU) nrDNA, translation elongation factor 1α (EF-1α), and β-tubulin (BT) gene sequences combination, eight Botryosphariaceae species, including Botryosphaeria dothidea, Diplodia citricarpa, Dothiorella plurivora, Dothiorella sarmentorum, Lasiodiplodia mahajangana, Lasiodiplodia theobromae, Neofusicoccum parvum and Neoscytalidium dimidiatum, were isolated and identified from Tamarix and Haloxylon species. Botryosphaeria dothidea, Neofusicoccum parvum, Lasiodiplodia theobromae and Neoscytalidium dimidiatum were recorded on both Tamarix and Haloxylon species, while the remaining species were detected only from Tamarix or Haloxylon species. Pathogenicity tests were conducted on detached shoots of Tamarix aphylla and Haloxylon ammodendron as well as branches of both tree species under field conditions. Lasiodiplodia mahajangana was the most virulent species and caused the longest wood lesion lengths on both tree species. Most of these species are reported for the first time from their respective hosts. Our findings in this study may be able to improve the basic information on the importance of Botryosphaeriaceae family on desert trees in Iran as well as other countries.

The present investigation attempted to postulate foxtail millet genotypes as putative host differentials for studying pathogen variability. Initially, a diverse panel of 95 genotypes were evaluated against foxtail millet leaf blast under field conditions at four different hotspot locations viz., Bangalore, Mandya. Nandyal and Vizianagaram during Kharif 2021. Based on the field reaction, 22 genotypes were selected for further screening under glasshouse conditions along with ISe175 (resistant check) and SiA326 (susceptible check). Four (4) leaf blast isolates namely FoxPs-3, 5, 6 and 15 from different locations were used to identify putative host differentials based on differential reaction. A set of 12 putative host differentials viz., ISe1256, GS55, GS2261, ISe1408, GS73, ISe1299, GS101, ISe746, ISe1655 and ISe1745 along with a resistant (ISe175) and susceptible check (SiA326), showing differential host responses were proposed as candidate host differentials to assess the pathogenic variability. The pathogenic profiling of 15 isolates on the identified putative host differential set has revealed four major pathogenic groups indicating the existence of pathotypes in Pyricularia population infecting foxtail millet in India. A set of putative host differentials identified and information on pathotypes of P. setariae is highly useful in better understanding of host pathogen interaction, existence of pathotype in a crop ecosystem and also serve as tools for identification of suitable disease resistant genotypes for resistant breeding programme.