Relações entre acilaçúcares, tricoma glandular e resistência do tomateiro à mosca branca

Abstract

RESUMO.Este trabalho foi desenvolvido com o objetivo de entender o envolvimento dos tricomas glandulares tipo IV, contendo acilaçúcares, na resistência de tomateiro à Bemisia argentifolii. Os genótipos utilizados foram: Lycopersicon esculentum 'TOM-584', desprovido de acilaçúcares e de tricomas tipo IV; L. pennellii 'LA-716', rico em acilaçúcares e em tricomas tipo IV; bem como suas plantas F 2 : BPX-370#30 e BPX-370#79. O experimento foi instalado em delineamento inteiramente casualizado com quatro tratamentos (genótipos), três e seis repetições dos parentais e dos clones F 2 , respectivamente. As quantificações dos tricomas tipo IV foram feitas do lado abaxial dos folíolos, em 20 cortes paradérmicos/planta, distribuídos em cinco folíolos/planta e quatro cortes/folíolo. As informações sobre os teores de acilaçúcares, bem como dos números de adultos mortos e ninfas vivas de mosca branca dos genótipos em teste, foram obtidas de outros estudos. Foram realizados contrastes entre as médias dos genótipos F 2 , para a densidade de tricomas, número de adultos mortos e de ninfas vivas de mosca branca. Não houve influência do tricoma tipo IV na resistência do tomateiro à mosca branca. A presença de adultos mortos do inseto nas plantas com este tipo de tricoma, bem como a ausência ou pequena quantidade de ninfas vivas, são explicadas pela ação dos acilaçúcares carreados por esse tipo de tricoma.Palavras-chave: Lycopersicon spp., Bemisia argentifolii, aleloquímicos, seleção indireta.ABSTRACT. Relationship between acylsugars, glandular trichome and resistance of tomato plants to the silverleaf whitefly. This work was carried out to understand the effect of glandular trichome type IV with acylsugars on the resistance to Bemisia argentifolii in tomato plants. The genotypes used were: Lycopersicon esculentum 'TOM-584', without acylsugars and type IV trichomes; L. pennellii 'LA-716', rich in acylsugars and type IV trichomes as well as its F 2 plants: BPX-370#30 and BPX-370#79. The experiment was established in a completely randomized design with four treatments (genotypes), three and six replications from the parents and F 2 plants, respectively. The trichome type IV quantification was made by using 20 paradermic cuts from the abaxial side of the leaflets; a sample of five leaflets per plant and four cuts per leaflet was used. A set data of acylsugars contents, number of dead adults and live whitefly nymphs, on the genotypes in test were obtained from other works. Contrasts were made between the medium of the trichome density of F 2 genotypes as well as the quantity of dead adults and live whitefly nymphs. It was not confirmed the influence of type IV trichomes on the quantity of dead adults and live nymphs. The respective presence and absence of dead adults and live whitefly nymphs, in tomato plants with type IV trichomes, is due to acylsugars contents in these trichomes.

Resistance to Bemisia tabaci biotype B of Solanum pimpinellifolium is associated with higher densities of type IV glandular trichomes and acylsugar accumulation

“…In summary, our results reinforce the hypothesis that resistance to B. tabaci in S. pimpinellifolium TO-937-15 and in their progenies is based upon a positive combination of high levels of acylsugar and high densities of type IV glandular trichomes, as also previously observed in populations and lines derived from S. pennellii (Freitas et al, 2002;Neiva et al, 2013). Resistance of S. pimpinellifolium TO-937-15 to the New World biotype B population found in this study suggests that it is also a source of wide spectrum resistance against distinct members of the B. tabaci complex.…”

“…Tomato resistance to B. tabaci is a highly desirable trait, as it can reduce insect infestations while reducing both the frequency of insecticide sprayings and production costs (Freitas et al, 2002). In the present study, we were able to select promising sources of B. tabaci biotype B resistance after screening 99 F 3 families derived from an interspecific cross between one commercial 'Santa Cruz' line and one accession of the wild species S. pimpinellifolium.…”

“…The trichomes of wild and domesticated Solanum species (section Lycopersicon) are categorized into glandular (I, IV, VI, and VII) and non-glandular (II, III, V, and VIII) types (Luckwill, 1943;Channarayappa et al, 1992;Peralta et al, 2008). Some Solanum pennellii Correll accessions have type IV glandular trichomes and secrete acylsugars, which are related to the resistance against a wide range of herbivores, including B. tabaci biotype B (Gentile et al, 1968;Goffreda et al, 1989;Lawson et al, 1997;Freitas et al, 2002;Maluf et al, 2010). Some Solanum pennellii Correll accessions have type IV glandular trichomes and secrete acylsugars, which are related to the resistance against a wide range of herbivores, including B. tabaci biotype B (Gentile et al, 1968;Goffreda et al, 1989;Lawson et al, 1997;Freitas et al, 2002;Maluf et al, 2010).…”

Influence of trichomes on attractiveness and ovipositional preference of Bemisia tabaci (Genn.) B biotype (Hemiptera: Aleyrodidae) on tomato genotypes

“…In addition to causing ovipositional nonpreference, whitefl ies may be trapped by exudates released by glandular trichomes (Toscano et al 2001, Freitas et al 2002, Muigai et al 2002, Fancelli et al 2003. The greatest number of trapped whitefl ies was found in PI134417 genotype (3.6), followed by 'Fanny' (1.8) and LA716 (1.5) (Table 1), and showed signifi cant and positive correlation to glandular trichomes (Table 3).…”

“…The non-glandular trichomes (II, III and V) are highly similar among themselves, differing only in length (Channarayappa et al 1992, Simmons & Gurr 2005, and the glandular trichomes (I, IV, VI and VII) are able to release alellochemicals that interfere with the ovipositional nonpreference of B. tabaci. In addition, whitefl ies may also be trapped in exudates liberated by glandular trichomes (Freitas et al 2002, Muigai et al 2002, Fancelli et al 2003.…”