Plant Cell Culture & Micropropagation - ISSN 1808-9909

SOMATIC EMBRYOGENESIS IN MAIZE: BACKGROUND AND EFFICIENCY

2016-04-18T10:01:29-03:00

The selection of efficient protocols to promote somatic embryogenesis and plant regeneration of maize (Zea mays L.), is a target that should contribute to the improvement of maize in Brazil. This process should encourage the transfer of genes and the development of genetically modified varieties. In the present review, protocols have been organized and developed for embryogenic callus induction and plant regeneration in order to evaluate the efficiency of the protocols that were used. One or more promising protocols for future investments was selected with genotypes of interest for genetic improvement. The investigations with different maize genotypes are concentrated in just over two decades (1989-2012), when only 17 studies were published and 179 genotypes were investigated, of which 77% formed embryogenic callus and only 43.5% regenerated plants in the absence or presence of amino acids and/or in different concentration of cytokinins and auxins. The N6 medium was the most used for callus induction (89.47% of investigations). The addition of L-proline, hydrolyzed casein, along with AgNO3 was detected in 84, 56, and 60% of the experiments, respectively. N6 medium containing 2.0 mg L-1 2.4-D has been used to analyze 46% of the genotypes. Through this process somatic embryogenesis has been induced in 87.9% of these cases. It has been three decades since the release of the first corn regenerant (1975), the competence for somatic embryogenesis and plant regeneration has been linked to being more dependent on genotype than on added supplements to the culture medium.

CARBON SOURCE ON in vitro MULTIPLICATION OF ‘MC’ AND ‘ADAMS’ QUINCE ROOTSTOCKS

2016-04-18T10:01:29-03:00

The objective was to determine the best carbon source and
concentration for in vitro multiplication of quince MC and Adams
cultivars. Nodal segments (1.0 cm and 1-2 buds) were inoculated
in MS and as a carbon source, sucrose, fructose or sorbitol were
used with the following concentrations: 0, 15, 30, 45 and 60 g L-1.
After 60 days, it was observed that, for ‘MC’, 60 g L-1 sucrose and
30 g L -1 fructose yielded 100% sprouted explants. The highest
shoot length average (1.49 cm) was obtained with 30 g L-1 sucrose
and 60 g L-1 sorbitol. The concentration of 45 g L-1 provided the
highest number of shoots (1.76), higher fresh mass (0.058 g) and higher dry matter (0.02 g), regardless of the carbon source. For ‘Adams’, the highest number of shoots (1.47) was obtained with sucrose and the higher dry mass of shoots (0.01 g) was obtained with sucrose and sorbitol. The sucrose concentration of 30 g L-1 provided the highest shoot lenght average (2.14 cm) and higher fresh weight (0.1 g) and 45 g L-1 sorbitol provided greater dry mass of shoots (0.03 g ). The highest percentage of sprouted explants was obtained at a concentration of 30 g L-1 (79.58%) and sucrose as carbon source (71.25%). The highest average number of shoots (1.45) was obtained with 30 g L-1. It was concluded that 45 g L-1 sucrose for ‘MC’ and 30 g L-1 sucrose for ‘Adams’ were the best concentrations for in vitro multiplication.

In vitro GERMINATION AND ACCLIMATIZATION OF EVERLASTING FLOWER

2016-04-18T10:01:29-03:00

Actinocephalus bongardii (A. St.-Hil.) Sano is a native
ornamental specie from Brazil, popularly known as evergreen
“showerhead” that presents potential for commercialization.
No effective propagation protocol for the species has yet been
established. The objective of this work was to establish an in vitro
germination protocol and acclimatization of A. bongardii. For the
in vitro culture, we evaluated MS and WPM culture media. Three
pH levels (4.8, 5.8 and 6.8) and five concentrations of gibberellic
acid (GA3) (0.0; 0.2; 0.4; 0.6 and 0.8 mg L-1) in WPM culture
media were evaluated. Percentage of germinated seeds, number
of leaves and length of the seedlings were evaluated 30 days after
inoculation. Seedlings obtained through the in vitro germination
were acclimatized with Plantmax® substrate in a greenhouse and
the percentage of seedlings survival were evaluated 30 days after acclimatization. The seeds inoculated in WPM showed highest germination percentage (74%) and seedlings with more leaves and longer length. The culture medium pH of 5.8 improved germination and the supplementation of the medium with 0.2 mg L-1 GA3 significantly increased the percentage of seed germination (94%). The acclimatization of the seedlings was only 50% due to the fragility of the tissues.

MULTIPLICATION AND in vitro ROOTING OF Campomanesia adamantium CAMB.

2016-04-18T10:01:29-03:00

The aim of this work was to evaluate the influence of
growth regulators BAP, IBA, NAA and IAA in the propagation
of Campomanesia adamantium CAMB. Nodal segments
from seedlings maintained in vitro at the fourth subculture
(subculture 40 to 40 days) were used. WPM culture medium

supplemented with 30 g L-1 sucrose, 7 g L-1 agar and 0.9 mM
PVP was used. For shoot induction, different concentrations
(0; 0.25; 0.5; 1.0 and 2.0 mg L-1) of BAP were tested. For
root induction, different concentrations (0.5; 1.0; 1.5 and 2.0
mg L-1) of IBA, NAA and IAA were used. The explants were
maintained in growth room with light intensity of 43 μmol
m-2 s-1 and a temperature of 25 ºC. We used a completely
randomized design with 5 replicates (each replicate with
three tubes). For shoot length, analysis of the experiment
was conducted in a factorial 2x5 (two evironments and five
concentrations). For the shoot variable, multiplication rate
and leaves presented no significant difference, but the length
shoot showed the highest average using 1.0 mg L-1 BAP
when induced in the dark. Results for root number were not
significant. The concentration indicated for shoot induction
is 1.0 mg L-1 BAP maintained in the dark for elongation. No
efficient protocol for root formation was obtained.