Wagner Campos Otoni

Effect of eggplant transformed with oryzacystatin gene on Myzus persicae and Macrosiphum euphorbiae

Abstract:  The effect of a genetically modified eggplant line expressing oryzacystatin on Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas) was examined. The transgenic eggplant reduced the net reproductive rate (R0), the instantaneous rate of population increase (r), and the finite rate of population increase (λ) of both aphids species compared with a control eggplant line. The mean generation time (T) of the aphids was unaffected by the transgenic plants. Age‐specific mortality rates of M. persicae and M. euphorbiae were higher on transgenic plants. These results indicate that expression of oryzacystatin in eggplant has a negative impact on population growth and mortality rates of M. persicae and M. euphorbiae and could be a source of plant resistance for pest management of these aphids.

Dinâmica do enraizamento de microestacas e miniestacas de clones de Eucalyptus grandis

The aim of this work was to evaluate the dynamics of microcutting and minicutting techniques during rooting process, by monitoring root emergence and development in microcuttings and minicuttings of four Eucalyptus grandis clones. Microcuttings were obtained from in vitro rejuvenated plant-derived sprouts, whereas minicuttings from rooted sprouts derived from plants propagated through conventional cutting technique. The results suggest the greater rooting ability of the microcuttings as compared to the minicuttings, evidenced by the number of roots/cuttings, total root/cutting length, largest root/cutting length, mean length of roots/cutting and dry weight of roots.

Desinfestação e germinação in vitro de sementes de mogno (Swietenia macrophylla King)

The objective of this work was to develop techniques of in vitro regeneration for mahogany (Swietenia macrophylla), using epicotyl segments, inverted epicotyls and leaf explants from mahogany plantlets germinated in culture medium. Also, the best concentration and time and sterilizing agent for seed sterilization were determined, as well as the best seed sowing position for germination. After tegument removal, seeds were sterilized in sodium hipochlorite solution at 0; 2,5 and 5,0% (v/v) concentrations, kept soaking for 10, 20, 30 and 40 minutes and inoculated in the culture medium in two positions: a) position 1 - with the concavity of the flat part turned upward, and b) position 2 - with the concavity of the flat part turned down. After sowing, seeds were kept in growth room with controlled temperature (±26 ± 2oC) and continuous dark. An entirely random factorial design, with 3 x 4 x 2 (sodium hipochlorite levels x soaking times x seed position), totaling 24 treatments with 3 repetitions was used. The germination stage and microorganism contamination were evaluated at 12, 18, 24 and 30 days after germination. The best treatments were seed sterilization in 2,5 and 5% sodium hipochlorite for 30 and 20 minutes, respectively, and both inoculated in position 2. These treatment also presented the highest germination rate (48%) and the lowest rates of microorganism contamination (15 e 10% respectively). As for position, a significant difference was detected for 24 and 30 days after sowing, with the largest means for seeds inoculated in position 2.

Efeito dos reguladores de crescimento dicamba e picloram na embriogênese somática em Eucalyptus grandis

The objective of this paper was to evaluate the effect of dicamba and picloram on the induction of somatic embryogenesis in mature zygotic embryos, cotyledons and hypocotyls of Eucalyptus grandis. Callus induction was obtained in MS culture medium with dicamba (0.25; 0.5; 1.0 and 2.0 mg L-1) or picloram (0.5; 1.5; 5.0 and 10.0 mg L-1). Treatments of cotyledonary explants with dicamba (0.5 mg L-1) or picloram (5.0 and 10.0 mg L-1) resulted in structures similar to somatic embryos, which appeared in different development stages. The histological analysis confirmed the presence of independent structures with an independent vascular system, suggesting that the structures are somatic embryos.

Enxertia in vitro na propagação de clones de Eucalyptus urophylla e E. grandis

The objective of this work was to evaluate the efficiency of the in vitro grafting in the propagation of two Eucalyptus urophylla and E. grandis hybrid clones. Juvenile stocks obtained from seeds of E. grandis and E. urophylla germinated in vitro were used. The grafted plants showed success up to 93% at 50 days for the scion and stock combinations. The highest final plant height values were observed when the stock was E. urophylla. Histologic analysis showed that cicatrized callus in the connection region was successfully followed by vascular recomposition in different combinations among scion with rootstocks.

In vitro shoot induction and multiplication from nodal segments of adult Ginkgo biloba plants

The in vitro performance of herbaceous and woody nodal segments from adult plants and the effect of hydrolyzed casein (HC 500 mg L-1), kinetin (KIN; 6-furfurylaminopurine 0.46 and 4.65 µM) and activated charcoal (AC 1.5 g L-1) were evaluated upon new shoots induction and development, and to establish a system of in vitro propagation from adult plants of Ginkgo biloba. Woody nodal segments did not produce axillary shoots and presented 100% of bacterial and fungal contamination in culture. However, nodal segments from herbaceous shoots were successfully disinfected and displayed high in vitro morphogenic capacity. The HC was essential for the axillary shoots induction and further multiplication, stimulating shoot formation in 85% of the cultured nodal segments and multiple shoots induction in 35% of them at establishment stage. During the multiplication stage, 66.6% of propagules formed new shoots and 33.3% of them formed multiple shoots when cultured with HC. The KIN and AC inhibited the organogenic process in ginkgo. Two distinct patterns of sprouts development were observed in vitro, similar to what occurs in vivo: 1) short shoots with crowded internodes and expansion of only a few leaves and slow growth; 2) long shoots with separated nodes and marked apical growth. This is the first report of multiple shoots in vitro formation in nodal segments obtained from adult plants of Ginkgo biloba.