Agrobacterium is widely considered, when suitably modified, to be the most effective vector for gene transfer into plant cells. For a long time, many cereals crops (monocotyledonous plants) were recalcitrant species to genetic modification, mainly as a result of their recalcitrance to in-vitro regeneration and their resistance to Agrobacterium infection. However, recently Agrobacterium-mediated transformation has been used to transform monocot crops such as maize (Zea mays) but with severe restrictions on genotype suitability. This study was carried out to evaluate the transformation amenability of 2 Syrian maize varieties and 2 hybrids in comparison with the hybrid line Hi II by the Agrobacterium tumefaciens-mediated transformation technique using a callus induction based system from immature zygotic embryos IZEs. A. tumefaciens strains EHA101, harbouring the standard binary vector pTF102, and the EHA105 containing the pBINPLUS/ARS:PpCBF1 vector were used. The effects of genotypes and the size of IZEs explants on callus induction and development were investigated. Results showed that callus induction and subsequent callus growth were significantly affected by the initial explant size. Calli induction from IZEs explants sized 1.5-2.00mm was 76%. Callus weight however decreased to 8.2g, compared with 11.7g of callus derived from IZEs >2.00mm. Callus induction ranged between 73.6-78.9% for varieties and hybrids respectively. Calli derived from varieties weighed significantly more than those initiated from the hybrids. Results demonstrated that Syrian maize genotypes were efficiently transformed via the A. tumefaciens strains but there was variation in transformation frequency. A transformation frequency of 3.7-4.2% was achieved for hybrids and varieties respectively confirming that the transformation frequency was genotype-dependent. The transformation frequency averaged between 3.2-5.6% for the EHA105 and EHA101 respectively. Fertile transgenic plants were regenerated from mature somatic embryos with an average regeneration frequency of 59.2 and 17% respectively for varieties and hybrids. Transgenic seeds of R0 and R1 progenies were produced from 74% of the outcrosses attempted and more than 98% of transgenic plants were normal in morphology. Fertile transgenic maize plants carrying the transferred gene CBF were produced using the Agrobacterium EHA105/PpCBF1 and these plants were shown to be more salt tolerant. Transient expression of the GUS gene was confirmed in transgenic calli, shoots, leaves, roots and floral parts of transgenic R0 and R1 progenies using histochemical GUS assays. The presence of the introduced bar and CBF genes in the genomic DNA of the transformants was confirmed by the PCR amplification. Further, the stable expression of the CBF and bar transgenes in the maize genome of transgenic R1 progeny was confirmed by qRT-PCR. The transformation protocol developed using an A. tumefaciens standard binary vector system was an effective and reproducible method to transform Syrian maize with an anti-stress gene in which fertile salt-resistant transgenic plants were routinely produced. This approach has great potential for development of Syrian maize breeding programmes for abiotic stress resistance for application in many areas in Syrian maize production.

The conservation of the coconut palm has been investigated in recent years by research organizations, public and private. These studies have concentrated on obtaining conservation protocols in vitro using slow growth and cryopreservation. Storage as a means of maintaining the viability of pollen, it is important for the preservation of genetic variability, facilitates the exchange of germplasm and contributes greatly to the generation of variability obtained from artificial crosses increasing the efficiency of breeding programs. The objective of this work was to study the effect of mannitol and abscisic acid (ABA) on growth of seedlings of coconut dwarf accessions for conservation purposes, and in vivo studies of the viability and storage conditions of pollen grains. For the study of conservation by slow growth were used mature zygotic embryos of Gramame Red Dwarf (AVG) and Malayan Yellow Dwarf (AAM). The coconut embryos were inoculated in culture medium Y3 (Eeuwens, 1976) supplemented with 30 g L-1 sucrose, gelled with 0.7% agar in presence of 2.5 g L-1 of activated charcoal. Were tested the following concentrations of mannitol: 0; 0.1; 0.2, 0.3 and 0.4 M. In other experiment was tested the following ABA concentrations: 0, 10, 20, 30 and 40 mM. The 0.1 and 0.2 M mannitol reduced the plantlets length of AAM and AVG accessions, respectively at 180 and 270 days of cultivation. Concentrations above 20 μM ABA were viable to inhibit the plantlets growth to 180 and 270 days. The ABA concentrations tested not inhibit the access AVG growth. For the study of determining the culture medium in germination of pollen grains, it was evaluated four culture media: Brewbaker and Kwack (1983) modified by Sousa et al. (2010); Lora et al. (2006); Sousa et al. (1998) and Sousa et al. (1998) modified by the author, in different times: 0, 24, 48 and 72 hours. The Lora culture medium promoted the major in vitro germination of AVeJBr pollen grains. Pollen grains of AVeJBr access showed viability up to 72 hours (3 days). The condition of storage at -20°C and -80°C promotes more viable pollen germination of AVC access up to 60 days. The condition of storage at -196°C promotes greater availability of pollen germination by AVeJBr access up to 60 days. / A conservação do coqueiro tem sido alvo de estudos nos últimos anos por organizações de pesquisa pública e privada. Essas pesquisas têm se concentrado na obtenção de protocolos por crescimento lento ou criopreservação. O armazenamento, como meio de manutenção da viabilidade do pólen, é importante para a preservação da variabilidade genética, facilita o intercâmbio de germoplasma e contribui muito na geração de variabilidade obtida através de cruzamentos artificiais aumentando a eficiência dos programas de melhoramento genético. O objetivo do trabalho foi de estudar o efeito do manitol e do ácido abscísico (ABA) no crescimento de plântulas de acessos de coqueiro anão para fins de conservação, além de estudos da viabilidade in vivo e condições de armazenamento de grãos de pólen. Para o estudo de conservação por crescimento lento foram utilizados embriões zigóticos maduros de acessos de coqueiro anão vermelho de Gramame (AVG) e anão amarelo da Malásia (AAM) e para estudos da viabilidade in vivo e condições de armazenamento de grãos de pólen o acesso anão verde de Jiqui do Brasil (AVeJBr). Os embriões foram inoculados em meio de cultura Y3 com 30 g L-1 de sacarose, geleificado com 0,7% de ágar na presença de 2,5 g L-1 de carvão ativado. Foram testadas as seguintes concentrações de manitol: 0; 0,1; 0,2; 0,3 e 0,4 M. Em outro ensaio o ABA foi adicionado ao meio de cultura nas concentrações de 0; 10; 20; 30 e 40 μM. As concentrações de 0,1 e 0,2 M de manitol reduziram o comprimento da parte aérea para os acessos AAM e AVG, respectivamente aos 180 e 270 dias de cultivo. Concentrações acima de 20μM do ABA foram viáveis para inibir o crescimento de plântulas aos 180 e 270 dias. O acesso AVG não sofreu inibição do comprimento da parte aérea, quando concentrações de ABA foram adicionadas ao meio de cultura. Foram avaliados quatro meios de cultura para germinação in vitro do acesso AVeJBr: Brewbaker & Kwack (1983) modificado por Sousa et al. (2010); Lora et al. (2006); Sousa et al. (1998) e Sousa et al. (1998) modificado pelo autor, em diferentes tempos: 0, 24, 48 e 72 horas. O meio de cultura de Lora promoveu a maior germinação de grãos de pólen do acesso AVeJBr. Grãos de pólen de coqueiro AVeJBr apresentaram viabilidade média, sob temperatura ambiente, até 72 horas (3 dias). A condição de armazenamento a -20°C e -80°C promove maior viabilidade de grãos de pólen por germinação do acesso AVC até os 60 dias. A condição de armazenamento a -196°C promove maior viabilidade de grãos de pólen por germinação do acesso AVeJBr até os 60 dias.

The conservation of the coconut palm has been investigated in recent years by research organizations, public and private. These studies have concentrated on obtaining conservation protocols in vitro using slow growth and cryopreservation. Storage as a means of maintaining the viability of pollen, it is important for the preservation of genetic variability, facilitates the exchange of germplasm and contributes greatly to the generation of variability obtained from artificial crosses increasing the efficiency of breeding programs. The objective of this work was to study the effect of mannitol and abscisic acid (ABA) on growth of seedlings of coconut dwarf accessions for conservation purposes, and in vivo studies of the viability and storage conditions of pollen grains. For the study of conservation by slow growth were used mature zygotic embryos of Gramame Red Dwarf (AVG) and Malayan Yellow Dwarf (AAM). The coconut embryos were inoculated in culture medium Y3 (Eeuwens, 1976) supplemented with 30 g L-1 sucrose, gelled with 0.7% agar in presence of 2.5 g L-1 of activated charcoal. Were tested the following concentrations of mannitol: 0; 0.1; 0.2, 0.3 and 0.4 M. In other experiment was tested the following ABA concentrations: 0, 10, 20, 30 and 40 mM. The 0.1 and 0.2 M mannitol reduced the plantlets length of AAM and AVG accessions, respectively at 180 and 270 days of cultivation. Concentrations above 20 μM ABA were viable to inhibit the plantlets growth to 180 and 270 days. The ABA concentrations tested not inhibit the access AVG growth. For the study of determining the culture medium in germination of pollen grains, it was evaluated four culture media: Brewbaker and Kwack (1983) modified by Sousa et al. (2010); Lora et al. (2006); Sousa et al. (1998) and Sousa et al. (1998) modified by the author, in different times: 0, 24, 48 and 72 hours. The Lora culture medium promoted the major in vitro germination of AVeJBr pollen grains. Pollen grains of AVeJBr access showed viability up to 72 hours (3 days). The condition of storage at -20°C and -80°C promotes more viable pollen germination of AVC access up to 60 days. The condition of storage at -196°C promotes greater availability of pollen germination by AVeJBr access up to 60 days. / A conservação do coqueiro tem sido alvo de estudos nos últimos anos por organizações de pesquisa pública e privada. Essas pesquisas têm se concentrado na obtenção de protocolos por crescimento lento ou criopreservação. O armazenamento, como meio de manutenção da viabilidade do pólen, é importante para a preservação da variabilidade genética, facilita o intercâmbio de germoplasma e contribui muito na geração de variabilidade obtida através de cruzamentos artificiais aumentando a eficiência dos programas de melhoramento genético. O objetivo do trabalho foi de estudar o efeito do manitol e do ácido abscísico (ABA) no crescimento de plântulas de acessos de coqueiro anão para fins de conservação, além de estudos da viabilidade in vivo e condições de armazenamento de grãos de pólen. Para o estudo de conservação por crescimento lento foram utilizados embriões zigóticos maduros de acessos de coqueiro anão vermelho de Gramame (AVG) e anão amarelo da Malásia (AAM) e para estudos da viabilidade in vivo e condições de armazenamento de grãos de pólen o acesso anão verde de Jiqui do Brasil (AVeJBr). Os embriões foram inoculados em meio de cultura Y3 com 30 g L-1 de sacarose, geleificado com 0,7% de ágar na presença de 2,5 g L-1 de carvão ativado. Foram testadas as seguintes concentrações de manitol: 0; 0,1; 0,2; 0,3 e 0,4 M. Em outro ensaio o ABA foi adicionado ao meio de cultura nas concentrações de 0; 10; 20; 30 e 40 μM. As concentrações de 0,1 e 0,2 M de manitol reduziram o comprimento da parte aérea para os acessos AAM e AVG, respectivamente aos 180 e 270 dias de cultivo. Concentrações acima de 20μM do ABA foram viáveis para inibir o crescimento de plântulas aos 180 e 270 dias. O acesso AVG não sofreu inibição do comprimento da parte aérea, quando concentrações de ABA foram adicionadas ao meio de cultura. Foram avaliados quatro meios de cultura para germinação in vitro do acesso AVeJBr: Brewbaker & Kwack (1983) modificado por Sousa et al. (2010); Lora et al. (2006); Sousa et al. (1998) e Sousa et al. (1998) modificado pelo autor, em diferentes tempos: 0, 24, 48 e 72 horas. O meio de cultura de Lora promoveu a maior germinação de grãos de pólen do acesso AVeJBr. Grãos de pólen de coqueiro AVeJBr apresentaram viabilidade média, sob temperatura ambiente, até 72 horas (3 dias). A condição de armazenamento a -20°C e -80°C promove maior viabilidade de grãos de pólen por germinação do acesso AVC até os 60 dias. A condição de armazenamento a -196°C promove maior viabilidade de grãos de pólen por germinação do acesso AVeJBr até os 60 dias.