Diversity and Pathogenicity of Diaporthe Species Revealed from a Survey of Blueberry Orchards in Portugal

Blueberries (Vaccinium corymbosum) are widely cultivated worldwide and largely consumed due to their known antioxidant and medicinal properties. Although Diaporthe species have been documented in Portugal as causal agents of blueberry twig blight and dieback, there is still scarce information on the species that cause these symptoms. Moreover, Diaporthe vaccinii, recently synonymized with D. eres, has been considered a concern to blueberry production worldwide. However, the current knowledge about its impact on blueberries remains unclear. The diversity of Diaporthe species associated with diseased blueberry plants were assessed through a national survey. A multilocus sequence analysis of the rDNA internal transcribed spacer (ITS) region, the translation elongation factor 1-alpha (tef1-α), β-tubulin (tub2), calmodulin (cal) and histone 3 (his3) genes unveiled the presence of Diaporthe ambigua, D. amygdali, D. crousii, D. foeniculina, D. hybrida, D. leucospermi, D. malorum and D. rudis. Moreover, all species were fully characterized based on a detailed morphological description. Diaporthe amygdali, D. hybrida, D. leucospermi and D. malorum are reported for the first time on diseased blueberries in Portugal. Results show that D. eres exhibited a high level of intraspecific variability within isolates, given that the strain CBS 160.32 might be a minor pathogen on blueberry plants, whereas CAA829 was revealed to be the most aggressive. Overall, this study also demonstrates that Diaporthe amygdali and D. eres may be two of the most aggressive species to blueberry plants. This study improves our understanding of the Diaporthe species and it’s causing of dieback and twig blight on Portuguese blueberry orchards. Additionally, the identification of these pathogens represents crucial information for blueberry producers to apply appropriate phytosanitary measures, as well as offering new insights into the potential pathogenicity of D. eres on this host.

Bottlenecks in Production and Marketing of Apple in Mountainous and Inaccessible Areas of Chenab Valley

Background: An attempt has been made in this study to identify the limitations encountered by the apple farmers in production and marketing which stall its growth in the study area. The present study has been carried out in the Jammu region of Jammu and Kashmir union territory with special emphasis on selected districts which fall under Chenab Valley, which is mostly hilly terrain and mountainous, as these regions had the highest area and production under apple crop.Methods: The primary data has been collected by survey method by interviewing the apple farmers as well as different market functionaries directly through an especially prepared and pre-tested schedule. The Identified constraints of the farmers in the production and marketing of apple had been ranked by making use of the Garrett’s Ranking Technique.Result: The analysis of the study revealed large number of constraints in the production and marketing of the commercial varieties of apple in a selected area, out of which occurrence of apple disease such as Stem Black, Powdery Mildew, Scab, Nectaria Twig Blight, Alternative Twig Blight, Peppery Dark/Pink Disease. Similarly, some of the common pests reported are: Woolly Aphids, San Jose Scale, Stem Borer, Root Borer, Bark Borer had been the major problem faced by the Growers, high labor cost, lack of latest technical knowledge, high cost of transportation, lack of transportation facilities and costly packing material have been identified as the major problems. In order to overcome the marketing problems of the study area apple producers should be organized as federation, cooperatives and union. The study calls for all government and non-governmental organizations to work together to expand and improve apple production and establish apple marketing hub for tackling the bottlenecks in the expansion of apple crop in the study area.

An Eleven-Year Survey on Field Disease Susceptibility of Citrus Accessions to Colletotrichum and Alternaria Species

In the past decade Colletotrichum gloeosporioides, C. karstii, and Alternaria alternata represent emerging fungal pathogens on citrus in the Mediterranean basin. Selection of tolerant Citrus germplasm offers evaluable long-term solution and should be considered as promising alternative to limit synthetic fungicide application to manage Alternaria and Colletotrichum infections in Citrus groves. In this study, the high variability of pre-harvest disease symptoms among 37 Citrus accessions was investigated in Italy in the most representative Sicilian production districts covering 1500 ha and including 20 homogeneous areas over an eleven-year survey period (2010–2020). Early fruit drop, brown spot, and anthracnose on fruit and leaves, pre-harvest fruit drop, and twig blight and defoliation associated to Alternaria and Colletotrichum spp. were identified on oranges, mandarins, and lemons. Comprehensively, first extensive data obtained herein on field susceptibility within “Tarocco” blood orange group to above disease symptoms clearly indicate as “Tarocco Nucellare 57-1E-1,” “Tarocco Tapi,” “Tarocco Sant’Alfio,” and “Tarocco Catania” accessions should be preferred to remaining Tarocco ones. A broad degree of tolerance or susceptibility was also observed within other Citrus group as it happens for tolerant lemon “Femminello Zagara Bianca,” thus demonstrating a putative resource for further studies to employ in a breeding program for genetic improvement of Citrus.

Response of Resistant and Susceptible Bayberry Cultivars to Infection of Twig Blight Pathogen by Histological Observation and Gibberellin Related Genes Expression

Bayberry is an important fruit tree native to the subtropical regions of China. However, a systematic twig blight disease caused by Pestalotiopsis versicolor and P. microspora, resulted in the death of the whole tree of bayberry. The main variety Dongkui is highly sensitive to the twig blight disease, but the variety Zaojia is very highly resistant to the disease. Therefore, it is very necessary to clear the difference between resistant and susceptible varieties in response to the fungal infection. In this paper, we investigated the response of resistant and susceptible bayberry cultivars to infection of twig blight pathogen by histological observation and gibberellin signaling pathway-related genes expression. Microscopic observation revealed the difference in the infection process between resistant and susceptible varieties. The results of frozen scanning electron microscopy showed that the Pestalotiopsis conidia were shrunk, the mycelium was shriveled and did not extend into the cells of resistant cultivars, while the conidia were full and the top was extended, the mycelia was normal and continued to extend to the cells of a susceptible cultivar. Indeed, the medulla cells were almost intact in resistant cultivar, but obviously damaged in susceptible cultivar after inoculation of the main fungal pathogen P. versicolor conidia, which is earlier germinated on sterile glass slide than that of a hard plastic slide. The quantitative real-time PCR results showed a significant difference between resistant and susceptible cultivars in the expression of gibberellin signaling pathway-related genes in leaves and stems of bayberry, which is closely related to infection time, the type of genes and varieties. Overall, this study provides a clue for our understanding of the resistance mechanism of bayberry against the twig blight disease.

Antifungal Effects of Rhizospheric Bacillus Species Against Bayberry Twig Blight Pathogen Pestalotiopsis versicolor

Bayberry is an attractive, nutritious, and popular fruit in China. The plant fungal pathogen Pestalotiopsis versicolor XJ27 is the causative agent of bayberry twig blight disease, which severely affects bayberry production. Traditional control techniques, such as chemical fungicides, are being used to control this disease; however, these techniques cause environmental and health hazards. In this study, we screened sweet potato rhizospheric bacteria with biocontrol potentials against P. versicolor XJ27, the bayberry twig blight pathogen. Ten isolates showed inhibition; Bacillus siamensis S3 and Bacillus tequilensis S5 showed the highest fungal growth inhibition. The antagonistic bacterial culture suspensions of S3 and S5 inhibited the mycelial growth by 82.9% and 76.2%, respectively. Their extracellular culture filtrates had mycelial growth inhibition of 86.8% and 82.2%, respectively. In detached leaf assay, the extracellular culture filtrates of S3 and S5 inhibited the size of the leaf lesion by 82.3% and 76.2%, respectively. SEM and TEM imaging showed a severe hyphal-damaged structure caused by the antagonistic bacteria. The fungal inhibition mechanisms might employ the hydrolytic enzymes and lipopeptides produced by the bacteria. Both the S3 and S5 have chitinase and protease activity; they produce a series of lipopeptides such as surfactin, iturin, and mycosubtilin. Therefore, we can suggest these bacteria as biocontrol agents for bayberry twig blight disease as an alternative to fungicides based upon their attributes of antifungal activity.

Draft genome assembly of Passalora sequoiae a needle blight pathogen on Leyland cypress

Objective Passalora sequoiae (family Mycosphaerellaceae) causes a twig blight on Leyland cypress that requires numerous fungicide applications annually to minimize economic losses for ornamental plant nursery and Christmas tree producers. The objective was to generate a high-quality draft assembly of the genome of P. sequoiae as a resource for primer development to investigate genotype diversity. Data description We report here the genome sequence of P. sequoiae 9LC2 that was isolated from Leyland cypress ‘Leighton Green’ in 2017 in southern Mississippi, USA. The draft genome was obtained using Pacific Biosciences (PacBio) SMRT and Illumina HiSeq 2500 sequencing. Illumina reads were mapped to PacBio assembled contigs to determine base call consistency. Based on a total of 44 contigs with 722 kilobase (kb) average length (range 9.4 kb to 3.4 Mb), the whole genome size was estimated at 31,768,716 bp. Mapping of Illumina reads to PacBio contigs resulted in a 1000 × coverage and were used to confirm accuracy of the consensus sequences.