PMC

Effect of root inoculation with selected Micromonospora strains (ALFb5 and ALFpr18c) on tomato resistance against Botrytis cinerea. (A) Symptom severity in leaves of tomato plants upon challenge with B. cinerea was determined by measuring the diameter of the necrotic lesions 42 h post-pathogen inoculation. Plants were grown in the absence of Micromonospora (Control) or inoculated at transplanting with Micromonospora strain ALFpr18c (pr18c) or strain ALF b5 (b5). Data not sharing a common letter are significantly different (Fisher’s protected LSD test at P ≤ 0.05). (B) Examples of B. cinerea symptom development in leaves of Micromonospora spp. inoculated (b5 or PR18c) or non-inoculated (control) plants.

Effect of Micromonospora ALFpr18c root inoculation on disease development caused by B. cinerea in different defense deficient tomato lines. (A) SA-deficient nahG and (B) JA-deficient def 1 plants. Necrosis severity caused by B. cinerea was scored using a three levels disease scale: mild, moderate and severe, as shown in Supplementary Figure . Control, plants not inoculated with Micromonospora; pr18c 1M and pr18c 1D, plants inoculated with Micromonospora sp. ALFpr18c 1 month or 1 day before challenge with B. cinerea, respectively. Within each genotype, bars not sharing a common letter (lowercase for mild, uppercase for moderate and greek for severe symptoms) are significantly different using Bonferroni corrected Chi-square tests, followed by z-tests (P ≤ 0.05).

Expression levels of the defense related genes PR1, LoxA, and PinII in leaves of tomato plants. Relative expression levels for PR1, LoxA, and PinII were determined by qPCR and normalized against the constitutive SlEF (tomato elongation factor α). Control: uninoculated, unchallenged plants; pr18c: plants inoculated with Micromonospora strain ALFpr18c; Botrytis: uninoculated plants challenged with B. cinerea; pr18c+Botrytis: plants previously inoculated with Micromonospora strain ALFpr18c and challenged with B. cinerea. Micromonospora inoculation was performed at transplanting, a month before infection with Botrytis. Data not sharing a common letter are significantly different according to Fisher’s protected LSD test at P ≥ 0.05.

Effect of Micromonospora ALFpr18c root inoculation on B. cinerea disease development in different tomato cultivars (Solanum lycopersicom L. ‘Moneymaker’ and ‘Castlemart’). Necrosis severity caused by Botrytis was scored using a three levels disease scale: mild, moderate and severe, as shown in Supplementary Figure . The number of leaflets within each category is shown. For each tomato cultivar, disease damage level was compared between the control and the bacterial treatments. Control, plants not inoculated with Micromonospora; pr18c 1M and pr18c 1D, plants inoculated with Micromonospora sp. pr18c 1 month or 1 day before challenge with B. cinerea, respectively. Bars not sharing a common letter (lowercase for mild, uppercase for moderate and greek for severe symptoms) are significantly different using Bonferroni corrected Chi-square tests, followed by z-tests (P ≤ 0.05).