Jatropha curcas L. oil has been shown to be suitable for the production of biodiesel. However, this species has not been domesticated yet. Genetic breeding through conventional methods is time consuming and costly, hence, genetic transformation could contribute positively to the improvement of interesting traits. Although in vitro regeneration and stable genetic transformation has been pursued for several years, variation in transformation efficiency remains strongly genotype-dependent and indicates that protocols optimization is still needed. Thus, this study was carried out to introduce a chitinase gene from the Trichoderma viride fungus into the genome of a J. curcas superior genotype by inoculating leaf explants with Agrobacterium tumefaciens EHA 105 strain in axenic conditions. Some key parameters such as pre-culture period and antibiotic doses were optimized with 500 mg.L -1 cefotaxime and 100 mg.L -1 kanamycin concentrations being suitable for A. tumefaciens inhibition and explant selection, respectively. The best transformation efficiency (50%) was obtained when leaf explants were incubated on a culture medium promoting shoot regeneration at 15 days before the induction of the transformation process. Plants where chitinase gene amplicons could be detected were assessed for transgene copy number and expression levels by quantitative real-time polymerase chain reaction (PCR). One, two and three copies of the introduced gene were confirmed in nine transgenic lines with two of them that were assessed for gene expression and showed quantitative variation for this variable. These results bring valuable information for further gene insertions in breeding programs of J. curcas for fungal disease resistance.
Interspecific hybridization is required for the development of Jatropha curcas L. improved cultivars, due to its narrow genetic basis. The present study aimed to analyze the parental genomic composition of F 1 and BC 1 F 1 generations derived from interspecific crosses (J. curcas/J. integerrima and J. curcas/J. multifida) by GISH (Genomic In Situ Hybridization), and the meiotic index and pollen viability of F 1 hybrids. In F 1 cells from both hybrids, 11 chromosomes of each parental was observed, as expected, but chromosome rearrangement events could be detected using rDNA chromosome markers, suggesting unbalanced cells. In the BC 1 F 1 , both hybrids had 22 chromosomes, suggesting that only n = 11 gametes were viable in the next generation. However, GISH allowed the identification of three and two alien chromosomes in J. curcas//J. integerrima and J. curcas//J. multifida BC 1 F 1 hybrids, respectively, suggesting a preferential transmission of J. curcas chromosomes for both hybrids. Pollen viability in F 1 hybrids derived from J. curcas/J. integerrima crosses were higher (82-83%) than those found for J. curcas/J. multifida (68%), showing post-meiotic problems in these last hybrids, with dyads, triads, polyads, and micronuclei as post-meiosis results. The here presented cytogenetic characterization of interspecific hybrids and their backcross progenies can contribute to the selection of the best genotypes for future assisted breeding of J. curcas.
Megaplatypus mutatus (Chapuis) é espécie nativa da América do Sul e é praga primária de espécies arbóreas exóticas e nativas. No município de Campinas, Estado de São Paulo, durante pesquisa realizada nos anos de 2004, 2005 e 2006, visando descobrir a causa da mortalidade de árvores que compõem o dossel de fragmentos de Floresta Estacional Semidecidual no Bosque dos Jequitibás e na Mata Santa Genebra, foi coletado material associado a várias espécies arbóreas ainda não registradas na literatura. Schizolobium parahyba (Vell.) S. F. Blake, Enterolobium contortisiliquum (Vell.) Morong, Livistona chinensis (Jacq.) R. Br., Caesalpinia pluviosa (Benth.) DC., Pittosporum undulatum Vent., Delonix regia (Bojer ex Hook) Raf., Mangifera indica L., Croton floribundus Spreng., Croton piptocalyx Müll. Arg., Cariniana legalis (Mart.) Kuntze, Luetzelburgia guaissara Toledo, Piptadenia gonoacantha (Mart.) J. F. Macbr., Ficus benjamina L., Platypodium elegans Vogel, Cariniana estrellensis (Raddi) Kuntze, Machaerium stipitatum (DC.) Vogel, Centrolobium tomentosum Guillemin ex Benth., Pachira aquatica Aubl., Inga cf. vera Willd. ssp. affinis (DC.) T.D. Penn., são registradas pela primeira vez como hospedeiros de M. mutatus no stado de São Paulo, Brasil. Plantas hospedeiras referidas em bibliografia também são relacionadas.
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