Silício alterando compostos derivados da pirólise de bainhas foliares de plantas de arroz infectadas por Rhizoctonia solani

Abstract

ResumoEste trabalho teve como objetivo elucidar, por meio da pirólise analítica acoplada à cromatografia gasosa e espectrometria de massa, alterações na composição química da lignina nas bainhas de plantas de arroz das cultivares BR-Irga 409 e Labelle supridas ou não com silício (Si) e infectadas por Rhizoctonia solani. A concentração de Si nas bainhas das plantas supridas com esse elemento foi significativamente maior (2,7 dag kg -1 ) em comparação com as plantas não supridas (0,45 dag kg -1 ). Na presença de Si, a área abaixo da curva do progresso da queima das bainhas foi significativamente reduzida em 19 e 25%, respectivamente, para as plantas das cultivares BR-Irga-409 e Labelle em relação à ausência desse elemento na solução nutritiva. Com base nos espectros de massas obtidos, foram identificados 33 compostos, dos quais 10 foram produtos da degradação de carboidratos e 23 derivados da lignina. Dentre os derivados da lignina, oito compostos eram do tipo p-hidroxifenila, 11 compostos do tipo guaiacila e quatro compostos do tipo siringila. Nas bainhas das plantas das duas cultivares de arroz, supridas ou não com Si, a concentração de lignina (p-hidroxifenila, siringila (S) e guaiacila (G)) foi de, aproximadamente, 15%. Houve aumento na relação S/G apenas nas bainhas das plantas da cultivar BR-Irga 409 supridas com Si e infectadas por R. solani. A maior concentração de Si nas bainhas das plantas de arroz das duas cultivares, que por sua vez resultou em aumento na relação S/G, contribuiu para reduzir os sintomas da queima das bainhas.Palavras-chave: queima das bainhas, lignina, metabólitos secundários, resistência. Silicon altering compounds derived from the pyrolyses of leaf sheaths of rice plants infected with Rhizoctonia solani AbstractThis study elucidated, through analytical pyrolysis coupled to gas chromatography and mass spectrometry, changes in the chemical composition of lignin on leaf sheaths of rice plants of cultivars BR-Irga 409 and Labelle supplied or non-supplied with silicon (Si) and infected with Rhizoctonia solani. The Si concentration on leaf sheaths of plants supplied with this element was significatively higher (2.7 dag kg ). In the presence of Si, the area under leaf sheath blight progress curve was significantly reduced by 19 and 25% for plants from cultivars BR-Irga 409 and Labelle, respectively, in comparison to the absence of Si. Based on the mass spectra obtained, 33 compounds were identified, 10 of which were products from the degradation of carbohydrates and 23 derivate from lignin. From lignin derivatives, eight compounds were p-hydroxiphenil type, eleven compounds were guaiacyl type and four compounds were syringyl type. On leaf sheaths of both cultivars, the concentration of lignin (p-hydroxiphenil, syringyl (S) and guaiacyl (G)) was around 15%, regardless of Si. There was no increase in the S/G ratio only for the leaf sheaths of BR-Irga 409 supplied with Si and infected with R. solani. High Si concentration on leaf sheaths of both cultivars, which in turn resulted in an increase...

Silicon, acibenzolar-S-methyl and potassium phosphite in the control of brown spot in rice

“…Many studies have investigated the effects of Si (Araujo et al 2016;Dallagnol et al 2011;Hayasaka et al 2008;Kim et al 2002;Rodrigues et al 2003Rodrigues et al , 2004Rodrigues et al , 2005Tatagiba et al 2014), ASM andPhi (Araujo et al 2008, 2015;Babu et al 2003;Rohilla et al 2001;Schurt et al 2013) on the reduction of diseases intensity in various plant species. However, regarding the rice-B.…”

“…Induced resistance has been used in rice for the control of bacterial leaf blight and sheath blight (Babu et al 2003;Rohilla et al 2001;Schurt et al 2013). The classic examples of inducible plant defense are systemic acquired resistance (SAR) and induced systemic resistance (ISR), which differ according to the nature of the elicitor and the host regulatory pathway involved (Knoester et al 1999;Métraux 2001;Ryals et al 1994;Vallad and Goodman 2004).…”

“…In contrast, the ISR is not related to PR-protein accumulation, is induced by biotic elicitors, and is signaled via the hormones ethylene and jasmonic acid (Knoester et al 1999;Métraux 2001;Ryals et al 1994;Vallad and Goodman 2004). In this context, some compounds such as the acibenzolar-S-methyl (ASM) and potassium phosphite (Phi) have shown the potential to induce resistance in different plants against pathogens (Araujo et al 2008(Araujo et al , 2015Babu et al 2003;Rios et al 2014;Schurt et al 2013).…”

“…In rice, the ASM showed its potential to reduce the severity of sheath blight and bacterial blight caused, respectively, by Rhizoctonia solani and Xanthomonas oryzae pv. oryzae (Babu et al 2003;Rohilla et al 2001;Schurt et al 2013).…”

“…The Phi, a salt of phosphorous acid, is a systemically mobile chemical that has been used in the management of diseases caused by different pathogens in many plant species (Araujo et al 2008(Araujo et al , 2010(Araujo et al , 2015Dalio et al 2014;Eshraghi et al 2011;Förster et al 1998;Junqueira et al 2011;Schurt et al 2013;Smillie et al 1989). The Phi products are registered as supplemental soil and foliar fertilizers for annual and perennial crops (Araujo et al 2008(Araujo et al , 2010Förster et al 1998;Junqueira et al 2011;Smillie et al 1989).…”