RESUMEN
KEY MESSAGE: The novel sunflower gene HaGLP1 is the first germin-like protein characterized from the family Asteraceae. It alters the host redox status and confers protection against Sclerotinia sclerotiorum and Rhizoctonia solani. Germin-like proteins (GLPs) are a large, diverse and ubiquitous family of plant glycoproteins belonging to the Cupin super family. These proteins have been widely studied because of their diverse roles in important plant processes, including defence. The novel sunflower gene HaGLP1 encodes the first germin-like protein characterized from the family Asteraceae. To analyse whether constitutive in vivo expression of the HaGLP1 gene may lead to disease tolerance, we developed transgenic Arabidopsis plants that were molecularly characterized and biologically assessed after inoculation with Sclerotinia sclerotiorum or Rhizoctonia solani. HaGLP1 expression in Arabidopsis plants conferred tolerance to S. sclerotiorum at the first stages of disease and interfered with R. solani infection, thus giving rise to significant protection against the latter. Furthermore, HaGLP1 expression in Arabidopsis plants elevated endogenous ROS levels. HaGLP1-induced tolerance does not appear to be related to a constitutive induction of the plant defence or the ROS-related genes examined here. In conclusion, our data suggest that HaGLP1 is an interesting candidate for the engineering of plants with increased fungal tolerance and that this gene could also be useful for the selection of naturally overexpressing sunflower genotypes for conventional breeding purposes.
Asunto(s)
Arabidopsis/metabolismo , Arabidopsis/microbiología , Ascomicetos/fisiología , Glicoproteínas/metabolismo , Helianthus/metabolismo , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente/microbiología , Especies Reactivas de Oxígeno/metabolismo , Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas/genética , Regulación de la Expresión Génica de las Plantas/fisiología , Glicoproteínas/genética , Helianthus/genética , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismoRESUMEN
In the present work we report new tools for the characterization of the complete chromosome complement of sunflower (Helianthus annuus L.), using a bacterial artificial chromosome (BAC) clone containing repetitive sequences with similarity to retrotransposons and a homologous rDNA sequence isolated from the sunflower genome as probes for FISH. The rDNA signal was found in 3 pairs of chromosomes, coinciding with the location of satellites. The BAC clone containing highly represented retroelements hybridized with all the chromosome complement in FISH, and used together with the rDNA probe allowed the discrimination of all chromosome pairs of sunflower. Their distinctive distribution pattern suggests that these probes could be useful for karyotype characterization and for chromosome identification. The karyotype could be subdivided into 3 clear-cut groups of 12 metacentric pairs, 1 submetacentric pair, and 4 subtelocentric pairs, thus resolving previously described karyotype controversies. The use of BAC clones containing single sequences of specific markers and (or) genes associated with important agricultural traits represents an important tool for future locus-specific identification and physical mapping.