Silicon induced resistance against powdery mildew of roses caused by Podosphaera pannosa

Abstract

Powdery mildew, caused by Podosphaera pannosa, is a very common disease in greenhouse potted roses, resulting in poor marketing value and hence economic losses. Alternatives to chemical control are necessary, and therefore the ability of silicon (Si) applied to roots to control the disease was investigated, as well as the mechanisms behind the observed disease reductions. Four genotypes of miniature potted roses representing different genetic backgrounds and susceptibility to disease were studied. Plants were watered with a nutrient solution containing either 3AE6 mM Si (100 ppm) supplied as K 2 SiO 3 (Si+) or no Si (Si)) before inoculation with P. pannosa. Si application increased leaf Si content two-to four-fold compared to control plants. Confocal microscopy showed that Si deposition was larger in Si+ than in Si) plants and that deposition mainly occurred in the apoplast, particularly in epidermal cell walls. Si application delayed the onset of disease symptoms by 1-2 days and disease severity was reduced by up to 48AE9%. The largest reduction was found in the two most resistant genotypes, which also had the highest increase in Si uptake. The Si-induced disease protection was accompanied by increased formation of papillae and fluorescent epidermal cells (FEC) as well as deposition of callose and H 2 O 2 , especially at the sites of penetration and in FEC, which are believed to represent the hypersensitive response. Si treatment reduced powdery mildew development by inducing host defence responses and can therefore be used as an effective eco-friendly disease control measure.

Identificación y alternativas de manejo de la cenicilla del rosal

“…: Fr) de Bary, una de las enfermedades más destructivas que se presenta tanto en rosas cultivadas al aire libre como en invernadero (Leus et al, 2006;Suthaparan et al, 2012). El hongo puede infectar todas las partes aéreas de la planta y bajo condiciones favorables provoca la distorsión de hojas y defoliación prematura (Shetty et al, 2012), lo que ocasiona pérdidas económicas significativas en la productividad, calidad y por ende en la comercialización (Suthaparan et al, 2010).…”

“…Such is the case of silicon, that has proven to have potential to improve the structural and biochemical potential for resistance to diseases such as powdery mildew in different crops such as cucumbers (Liang et al, 2005), strawberries and grapes (Botta et al, 2011), as well as in pot roses (Shetty et al, 2012). Likewise, phosphites are capable of controlling diseases in diverse crops, Volumen 34, Número 1, 2016 son, 2005); además la necesidad de minimizar el uso de fungicidas conduce a la búsqueda de alternativas de control como el uso de inductores de defensa; tal es el caso del silicio, que ha mostrado su potencial para mejorar los componentes estructurales y bioquímicos de resistencia a enfermedades como la cenicilla en diferentes cultivos como pepino (Liang et al, 2005), fresa y uva (Botta et al, 2011) y en rosas para maceta (Shetty et al, 2012). Así mismo, los fosfitos tienen la capacidad de controlar enfermedades en diversos cultivos, actuando directamente sobre el patógeno e indirectamente mediante la estimulación de respuestas de defensa del hospedante (Deliopoulos et al, 2010); al respecto, se reportó que el fosfito de potasio induce resistencia en el cultivo de papa a Phytophthora infestans (Mont) de Bary (Machinandiarena et al, 2012) y reduce significativamente la incidencia y severidad de Oidium sp.…”

“…: Fr) de Bary, one of the most destructive diseases for roses grown in the open air and greenhouses (Leus et al, 2006;Suthaparan et al, 2012). The fungus can infect all the aerial parts of the plant, and under favorable conditions, causes the distortion of leaves and premature defoliation (Shetty et al, 2012), which causes significant economic losses in the productivity, quality, and therefore, in marketing (Suthaparan et al, 2010).…”

“…Continuously applying these chemicals increase production costs and may bring about selections of resistant P. pannosa populations (Daughtrey and Benson, 2005); also, the need to minimize the use of fungicides leads to search for control alternatives such as the use of defense inducers. Such is the case of silicon, that has proven to have potential to improve the structural and biochemical potential for resistance to diseases such as powdery mildew in different crops such as cucumbers (Liang et al, 2005), strawberries and grapes (Botta et al, 2011), as well as in pot roses (Shetty et al, 2012). Likewise, phosphites are capable of controlling diseases in diverse crops, Volumen 34, Número 1, 2016 son, 2005); además la necesidad de minimizar el uso de fungicidas conduce a la búsqueda de alternativas de control como el uso de inductores de defensa; tal es el caso del silicio, que ha mostrado su potencial para mejorar los componentes estructurales y bioquímicos de resistencia a enfermedades como la cenicilla en diferentes cultivos como pepino (Liang et al, 2005), fresa y uva (Botta et al, 2011) y en rosas para maceta (Shetty et al, 2012).…”

Aspectos bioquímicos da resistência do algodoeiro à ramulose potencializada pelo silício

“…corroboram os encontrados por Shetty et al (2012), que observaram atraso no aparecimento dos sintomas e redução na severidade do míldio pulverulento em roseira suprida com Si. Resende et al (2009) obtiveram aumento no PI e PL 60 e redução da eficiência relativa de infecção e a área abaixo da curva do progresso da antracnose nas folhas de uma linhagem suscetível de sorgo com a aplicação de silicato de cálcio no solo.…”