Structural and biochemical characteristics of citrus flowers associated with defence against a fungal pathogen

Autor(es)

Rodrigues Marques, Joao Paulo ^[1] ; Amorim, Lilian ^[1] ; Silva-Junior, Geraldo Jose ^[2] ; Sposito, Marcel Bellato ^[1] ; Appezzato-da Gloria, Beatriz ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Escola Super Agr Luiz de Queiroz, BR-13418900 Piracicaba, SP - Brazil

^[2] Fundo Def Citricultura FUNDECITRUS, BR-14807040 Araraquara, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: AOB PLANTS; v. 7, 2015.
• Citações Web of Science: 11

Resumo

The constitutive characters of plants can be structural or biochemical and play an important role in their defence against pathogens. Citrus postbloom fruit drop (PFD) caused by Colletotrichumspp. is one of the most important fungal diseases of citrus. The pathogen infects the flowers, leading to premature fruit drop and reducing citrus production. However, flower buds smaller than 8 mm long are usually not infected by Colletotrichum spp. Thus, this study investigated whether there are constitutive mechanisms in flower buds related to Colletotrichum spp. infection. We studied flower buds that were 2, 3, 4, 8, 12 and 15 mm long and petals, after anthesis, of sweet orange `Valencia' using light and scanning electronmicroscopy and histochemistry. We evaluated the effect of volatile organic compounds (VOCs) in flowers (R-limonene and linalool) on the in vitro growth of Colletotrichumacutatum. We found that the arrangement of the epidermal papillae in the petal primordia, the occurrence of prismatic crystals and the distribution of oil glands are the main differences between buds smaller than 8 mm and buds 8-15 mm long. Osmophores at the tips of petals produced and accumulated phenols, terpenes and lipophilic compounds. Flower buds smaller than 8 mm long have constitutive structural and biochemical barriers to Colletotrichum spp. infection. In addition, this is the first time that osmophores have been reported in citrus. Our study shows that natural terpenes of Citrus flowers inhibit the fungal growth in vitro, highlighting the potential use of terpenes for the chemical control of PFD in citrus. (AU)

• Processo FAPESP: 09/00425-6 - Podridão floral dos citros: histopatologia de Colletotrichum acutatum
• Beneficiário: João Paulo Rodrigues Marques
• Linha de fomento: Bolsas no Brasil - Doutorado