MA Monachesi1, RP Bertani2, MA Debes3,4 and ME Arias4,5
1Instituto de Tecnología Agroindustrial del Noroeste Argentino (ITANOA), Estación Experimental Agroindustrial Obispo Colombres (EEAOC) – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), CCT NOA Sur – Las Talitas, Tucumán, R. Argentina, T4101XAC; mmonachesi@eeaoc.org.ar
2Estación Experimental Agroindustrial Obispo Colombres (EEAOC) – Las Talitas, Tucumán, R. Argentina, T4101XAC
3Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) y Facultad de Bioquímica, Química y Farmacia (UNT) – San Miguel de Tucumán, Tucumán, R. Argentina, T4000ILI
4Cátedra Anatomía Vegetal, Facultad de Ciencias Naturales e Instituto Miguel Lillo (FCN e IML-UNT) – San Miguel de Tucumán, Tucumán, R. Argentina, T4000ILI
5Centro Regional de Energía y Ambiente para el Desarrollo Sustentable (CREAS), Universidad Nacional de Catamarca (UNCA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Catamarca, R. Argentina, K4700
Red stripe (RS) in sugarcane [Acidovorax avenae subsp. avenae (Aaa)] is considered a non-systemic disease; however, understanding the colonization pattern of the pathogen is essential for proposing alternative management strategies in conjunction with the use of resistant sugarcane cultivars. The aims of this research were to analyze the histological damage caused by Aaa in sugarcane leaf tissue and to evaluate the efficacy of a plant defense inducer for RS management. Sections of sugarcane leaves inoculated with a GFP-expressing Aaa strain were analyzed using epifluorescence and bright-field (BF) microscopy. Additionally, leaves showing severe RS symptoms were fixed and further examined using BF microscopy. Preventive applications of acibenzolar-S-methyl (50%) were tested at four timings (3, 6, 8, and 6+8 days before inoculation) and three doses (0.16, 0.32, and 0.50 mg/mL) under controlled conditions to evaluate the impact on RS severity. The Area Under the Disease Progress Curve (AUDPC) and control efficacy were calculated. Leaf tissues inoculated with Aaa–GFP exhibited fluorescence in vascular bundle sheaths and intercellular spaces due to cell wall rupture; additionally, BF microscopy revealed granularity in the affected tissues. Severe RS symptoms included mesophyll collapse, epidermal folding, red-brown deposits, increased fiber layers, and thickened sub-epidermal walls. Application of 0.16 mg/mL of acibenzolar-S-methyl, 8 days before bacterial inoculation, achieved an RS control efficacy of 31.86%. These results provide insights into the tissue-specific impacts of Aaa and highlight the potential of acibenzolar-S-methyl for sustainable RS management.