Publications

4603

Comparison of the metabolic changes prior to symptom development upon infection with Candidatus Liberibacter asiaticus (CLas), the bacterium associated with citrus greening disease, between citrus hosts with different tolerances is lacking. The objective of this study was to compare the early response of Lisbon lemon (Citrus limon) and Washington navel orange (Citrus sinensis [L.] Osbeck), two citrus species commercially important to California, to CLas through graft inoculation. Here, we compare the transcriptome, proteome, and metabolome response, using RNA sequencing, liquid chromatography tandem mass spectrometry, and 1H nuclear magnetic resonance, respectively, from our two recently published studies examining the response of the lemon and navel oranges separately, and introduce new micronutrient data from inductively coupled plasma mass spectrometry analysis, focusing on lemons at 10 and 14 weeks postgrafting (wpg), and navels at 8 and 18 wpg, prior to symptom development. Several micronutrients accumulated in presymptomatic infected lemons compared with controls, whereas little change was observed in the navels. Photosynthesis proteins were substantially altered by CLas infection in navels, with fewer changes observed in lemons. The metabolome differed between control and infected navels throughout infection, although differences between control and infected lemons were identified only after symptom expression. Taken together, these findings highlight differences in response to CLas between two varieties with differing tolerances. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Abstract RUS is of considerable economic importance, especially in areas where outbreaks occur. It has been described as a serious and widespread problem of raspberry in the former Soviet Union (see van der Meer (1987) for references). After the First World War, the disease became disastrous in raspberry areas in southern parts of The Netherlands, and many young plantations, started with healthy plant material, contained 60-90% infected plants in the second year after planting (see van der Meer (1987) for references). Small outbreaks and/or incidental occurrences of RUS disease have been reported from several other European countries (van der Meer, 1987).

Abstract Aster yellows (AY) group phytoplasmas affect plants by causing a general reduction in quantity and quality of yield. The most severely affected hosts are carrot, lettuce, onion, spinach and several ornamental crops, including aster, gladiolus, hydrangea, chrysanthemum and purple coneflower. Disease incidence may vary from year to year depending on the population trend of the vectors in the field. Infection rates varying from 20 to 30% were observed in lettuce and ranunculus fields in southern Italy (Marcone et al., 1995; Parrella et al., 2008). In Oklahoma, USA, according to Errampalli et al. (1991), AY group phytoplasma infections occurred in 80% of lettuce plants and 28% of carrots. In Ohio, disease incidence of 100% has been recorded in lettuce fields (Zhang et al., 2004). A major outbreak of AY disease occurred in 2000 in Texas that affected several vegetable crops. Among them, carrot was most severely damaged with infection rates that ranged from to 50 to near 100% (Lee et al., 2003). A severe AY disease of chrysanthemum which induced losses of 70 to 80% of the crop has been reported from China (Min et al., 2008) whereas losses of 90% were recorded in AY-affected aubergines in Bangladesh (Kelly et al., 2009). Infection rates of 60 and 99% were recorded in Hungary for AY-affected sugarbeet plants and India for AY-affected Jatropha curcas plants, respectively (Mumford et al., 2000; Kumar et al., 2010b). However, there are also several reports on sporadic occurrence and generally low incidence of AY group phytoplasmas in vegetable and ornamental crops (Smith et al., 1988; Vibio et al., 1995; Bertaccini et al., 1998). Cassava witches' broom, a disease affecting cassava in South East Asia (Vietnam, Thailand, Cambodia, Laos, China and the Philippines) is caused by 16SrI phytoplasma. The disease has resulted in significant reductions in cassava root starch content and up to 80% yield loss in parts of Vietnam (Anon., 2014).