Abstract NAC transcription factors are plant-specific proteins involved in many processes during the plant life cycle and responses to biotic and abiotic stresses. Previous studies have shown that stress-induced OsNAC5 from rice (Oryza sativa L.) is up-regulated by senescence and might be involved in control of iron (Fe) and zinc (Zn) concentrations in rice seeds. Aiming a better understanding of the role of OsNAC5 in rice plants, we investigated a mutant line carrying a T-DNA insertion in the promoter of OsNAC5, which resulted in enhanced expression of the transcription factor. Plants with OsNAC5 enhanced expression were shorter at the seedling stage and had reduced yield at maturity. In addition, we evaluated the expression level of OsNAC6, which is co-expressed with OsNAC5, and found that enhanced expression of OsNAC5 leads to increased expression of OsNAC6, suggesting that OsNAC5 might regulate OsNAC6 expression. Ionomic analysis of leaves and seeds from the OsNAC5 enhanced expression line revealed lower Fe and Zn concentrations in leaves and higher Fe concentrations in seeds than in WT plants, further suggesting that OsNAC5 may be involved in regulating the ionome in rice plants. Our work shows that fine-tuning of transcription factors is key when aiming at crop improvement. plantspecific specific stresses stressinduced stress induced OsNAC Oryza L. L upregulated up regulated (Fe (Zn plants TDNA T DNA factor maturity addition coexpressed co expressed finetuning fine tuning improvement

ABSTRACT: Seedlessness in fruit is a trait that is much sought after by juice making industries. Close to the city of São Sebastião do Caí, in the state of Rio Grande do Sul (RS), Brazil, a new mutant orange originating from natural mutation was identified and selected as a seedless material. To determine the mechanisms involved in the absence of seeds, the reproductive structures of this new mutant by comparison with a Valencia sweet orange as control, a cultivar with a profusion of seeds, was analyzed in terms of meiotic behavior, meiotic index, pollen viability, in vitro germination, and ovule features to determine the grounds for seed absence. Other morphological analyzes allowed for visualizing the structures of normal appearance and size in both cultivars. Meiotic analysis identified chromosome normal pairing with a predominance of bivalents at diakinesis and metaphase 1. URS Campestre flowers at different developmental stages had anthers and ovaries whose dimensions are typical while pollen grain analysis pointed to a standard developmental pattern, normal meiosis, high viability (84 %) and elevated in vitro pollen tube germination rates (63 %). The cv. Valencia and URS Campestre ovules had a similar shape and morphology, sharing an anatropous orientation, and two integuments. In the internal ovule analyses of Valencia sweet oranges, normal embryo sac cells were identified: presence of one egg cell and two synergids, three antipodes and a bigger and central cell containing two polar nuclei. However, the analysis of ovules from URS Campestre reveals an apparent senescence or non-formation of an embryo sac, where only a few highly stained and collapsed cells could be identified. These results led to the conclusion that female sterility in URS Campestre, with a total absence of a female gametophyte, is the limiting factor for fertilization and seed production.

As doenças de pós-colheita são fatores limitantes para estocagem de produtos colhidos. É crescente o interesse por métodos alternativos para o controle de podridão em pós-colheita. A termoterapia pré-estocagem parece ser um método promissor podendo ser aliado a outros métodos alternativos. O objetivo deste trabalho foi verificar os efeitos do tratamento térmico por aspersão e imersão na cutícula de maçãs (Malus domestica Borkh.) Fuji e Gala após tratamento e período curto de armazenagem. Foram realizados seis tratamentos, com três repetições de três frutos: testemunha, imersão em água quente a 58ºC-30 s, 1 e 2 min., aspersão em água quente a 58ºC-30 s; imersão em clorofórmio 30 segundos. Foram retiradas amostras para visualização em microscopia eletrônica de varredura na instalação e três semanas de armazenamento a 0ºC. Durante a armazenagem, as rachaduras da cutícula aumentam em largura, sendo esta uma característica importante na pós-colheita, pois estas propiciam maior perda de água e podem tornar-se sítios de penetração de patógenos. O calor derrete os cristaloides de cera da cutícula para formar um padrão de recobrimento mais homogêneo na superfície e a oclusão de fraturas, podendo atuar como barreira física para evitar a entrada de patógenos nas maçãs bem como reduzir a perda de massa fresca.

Postharvest diseases are limiting factors to the storage of many crops. There is a growing interest in alternative methods to control postharvest diseases. Pre-storage heat treatment seems to be one of the most promising rot control methods, associated with other alternative methods. The objective of this work was to verify the effects of immersion and spraying heat treatment on the cuticle of Fuji and Gala apples (Malus domestica Borkh.) right after treatment and a short storage period. This experiment consisted of six treatments, three replications of three fruits each: no treatment; hot water immersion at 58ºC for 30 s, 1 and 2 min.; hot water spraying at 58º C for 30s; chloroform immersion for 30s. Samples were excised to visualize on scanning electron microscope at onset and after three weeks storage at 0ºC. During the storage period, cracks of the cuticle layer got wider. Heat acts melting the crystalloids on the cuticle layer, and the melting forms a more homogeneous covering pattern on the apple surface. Heat caused occlusion of fractures by melting waxes, showing this is one of the probable effects of heat on the fruit, which could be acting as a physical barrier to avoid the entrance of pathogen in the apple, as well as reducing fresh weight loss.

Há uma grande carência de pesquisas e literatura no Brasil sobre a reprodução do pessegueiro. A presente revisão de literatura aborda e confronta inúmeros resultados de pesquisas acerca dos principais fatores envolvidos na reprodução dessa frutífera, com o intuito de subsidiar futuras pesquisas que visam ao melhor entendimento e/ou à solução de problemas associados à sua reprodução. Através da presente revisão, foi possível verificar que o processo de fixação de frutos se mostra complexo para algumas cultivares, sendo dependente da passagem, com êxito, por cada estádio fenológico. Com isso, a habilidade dos técnicos e produtores em integrar os fatores porta-enxerto, cultivar, ambiente e manejo das plantas é crucial para o sucesso no cultivo dessa espécie frutífera.

In Brazil there is a great lack of studies and literature about the peach reproduction. The present review discusses a lot of research results regarding the main factors involved in the reproduction of this species, and it has the intention to help future researches that aims to understand or to resolve the problems associated with the reproduction of the peach tree. By this review it was possible to verify that the process of fruit set is complex for some cultivars and highly dependent on each phenological stage. The ability of the professionals and producers to integrate the factors rootstocks, variety, environment and adequate cultural practices is very important for a successful peach tree production.

Estudos palinológicos revelam uma ampla variação de formas, número e tipos de aberturas nos grãos de pólen em Passiflora. Este estudo tem como objetivo caracterizar as aberturas polínicas de onze espécies do gênero ocorrentes no Rio Grande do Sul e duas em Santa Catarina (Brasil), pertencentes a três dos quatro subgêneros atualmente reconhecidos: Astrophea, Decaloba e Passiflora. Foram utilizadas várias técnicas de microscopia óptica de campo claro e microscopia eletrônica de varredura. Passiflora haematostigma (Astrophea) possui grãos de pólen 6-colporados, com três endoaberturas lalongadas. Passiflora alata, P. amethystina, P. caerulea e P. edulis (Passiflora) apresentam pólen 6-colpados, com fusões das ectoaberturas, aos pares, na região do apocolpo. Passiflora actinia, P. elegans e P. tenuifila (Passiflora) apresentam grãos de pólen com 6 a 12 colpos, também fusionados aos pares. Passiflora misera, P. morifolia, P. suberosa e P. truncata (Decaloba) apresentam grãos de pólen 6-colporados operculados, com diferenças no tamanho das endoaberturas e largura do opérculo. Passiflora capsularis (Decaloba) apresenta pólen 12-colporado. São discutidos os principais termos relacionados às descrições polínicas do grupo e indicados os termos mais apropriados e sinônimos.

Palynological studies reveal a wide variation in shape, number and types of apertures in Passiflora pollen grains. This study aimed to characterize pollen grain apertures of eleven species of Passiflora from Rio Grande do Sul state and two species from Santa Catarina state (Brazil), belonging to three of the four subgenera now recognized: Astrophea, Decaloba and Passiflora. Several techniques of light and scanning electron microscopy were employed. Passiflora haematostigma (Astrophea) has 6-colporate pollen grains with three lalongate endoapertures. Passiflora alata, P. amethystina, P. caerulea and P. edulis (Passiflora) have 6-colpate pollen grains, with fusion of ectoapertures pairs in the apocolpium. Passiflora actinia, P. elegans and P. tenuifila (Passiflora) have pollen grains with 6 to 12 colpi, also fused in pairs. Passiflora misera, P. morifolia, P. suberosa and P. truncata (Decaloba) have 6-colporate operculate pollen grains, with differences in endoaperture size and operculum width. Passiflora capsularis (Decaloba) has 12-colporate pollen. The main palynological terms and synonyms in the literature are discussed.

A presença de substâncias de reserva na forma de grãos de amido, proteínas e lipídios foi analisada durante a gametogênese masculina em Ilex paraguariensis St.Hil. (Aquifoliaceae). Foram encontrados dois ciclos de amilogênese e amilólise. O primeiro estende-se até a fase de andrósporo vacuolado, quando todo o amido presente é hidrolizado e proteínas, na forma amorfa, são estocadas no interior do único vacúolo do andrósporo. O segundo ciclo inicia a partir da formação das células generativa e vegetativa, sendo que esta última estoca grande quantidade de grãos de amido, maiores que os do primeiro ciclo. Todo o amido é hidrolizado durante a maturação do andrófito e a formação da unidade reprodutiva masculina. Gotas lipídicas circundam a célula generativa durante seu englobamento e estão dispersas no citoplasma vegetativo no andrófito maduro. A síntese e degradação de substâncias de reserva podem estar relacionadas com a formação dos estratos da esporoderme e ontogenia do andrófito binucleado.

Storage substances such as starch grains, proteins and lipids were studied during the male gametogenesis and in the mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae). There are two cycles of amylogenesis and amylolyse. The first cycle lasts until the vacuolated stage when the starch is hydrolyzed and amorphous proteins are stored inside the single vacuole. The next cycle begins after mitosis with the formation of the vegetative and generative cells. At this point, the young vegetative cell stores many starch grains that are bigger than in the first cycle. During the maturation of the male gametophyte, the starch is hydrolyzed and it is absent in the mature pollen grain. Small lipid droplets surround the young generative cell after the mitosis of the androspore and are dispersed in the vegetative cytoplasm during its maturity. The relationship between the pollen storage substances and the ontogeny of the layers in the sporoderm, formation of the generative cell, and the male germ unit were discussed.