ABSTRACT
A disease forecast model for Marssonina blotch of apple was developed based on field observations on airborne spore catches, weather conditions, and disease incidence in 2013 and 2015. The model consisted of the airborne spore model (ASM) and the daily infection rate model (IRM). It was found that more than 80% of airborne spore catches for the experiment period was made during the spore liberation period (SLP), which is the period of days of a rain event plus the following 2 days. Of 13 rain-related weather variables, number of rainy days with rainfall ≥ 0.5 mm per day (L day ), maximum hourly rainfall (P max ) and average daily maximum wind speed (W avg ) during a rain event were most appropriate in describing variations in air-borne spore catches during SLP (S i ) in 2013. The ASM, S i = 30.280+5.860×L day ×P max -2.123×L day ×P max ×W avg was statistically significant and capable of predicting the amount of airborne spore catches during SLP in 2015. Assuming that airborne conidia liberated during SLP cause leaf infections resulting in symptom appearance after 21 days of incubation period, there was highly significant correlation between the estimated amount of airborne spore catches (S i ) and the daily infection rate (R i ). The IRM, RÌ i = 0.039+0.041×S i , was statistically significant but was not able to predict the daily infection rate in 2015. No weather variables showed statistical significance in explaining variations of the daily infection rate in 2013.
ABSTRACT
Four samples of Plantago asiatica showing mottle or mottled yellowing symptoms were collected and three of them were confirmed to be infected with Plantago asiatica mosaic virus (PlAMV) by Illumina HiSeq 2500 paired-end RNA sequencing. Consequently, the complete genomic sequence of a Korean isolate of PlAMV (PlAMV isolate Gunwi) from P. asiatica was determined. The nucleotide sequence of PlAMV-Gunwi was most closely related to a Russian isolate of PlAMV (PlAMV-Ru) collected from P. asiatica but highly dissimilar (~23 %) to other isolates of PlAMV from other plant species. Pairwise comparisons revealed that the complete replicase protein and coat protein of PlAMV-Gunwi share 85.15-91.20 and 84.54-90.82 % amino acid sequence identities, respectively, to the corresponding proteins of other PlAMV isolates. To our knowledge, this is the first report of the natural infection of P. asiatica by PlAMV in Korea, and the divergent PlAMV isolate Gunwi expands our understanding of the epidemiology of PlAMV.
