Abstract: The banana tree is associated with different species of endophytic bacteria that can stimulate plant growth. However, further studies are needed to better understand the relationships between this group of bacteria and the host plant. The objective of this study was to investigate the localization of the EB-40 (Bacillus sp.) through anatomical and ultrastructural analyses in micropropagated banana plantlets. The results demonstrated the effective colonization of the EB-40 isolate in the intercellular and intracellular spaces, as well as in the rhizosphere region. The wall of endophytic bacteria contains calcium and nitrogen. The EB-40 isolate was also observed to associate with the plasma membrane and cell wall. These results further our understanding of the mechanisms involved in the colonization of plant cells by endophytic bacteria in micropropagated banana plantlets.

ABSTRACT Forty isolates of endophytic bacteria isolated from banana tree roots were assessed as to their capacity to solubilize phosphate in a solid culture medium supplemented with different inorganic and one organic source of phosphorus. The amount of phosphorus (P) in each liquid medium was quantified, and an indirect assessment of acid phosphatase activity was performed. All assays had a fully randomized design, with three repetitions. Approximately 67.5% of the 40 isolates assessed in solid medium solubilized phosphorus from tricalcium phosphate and 7.5% of the isolates solubilized phosphorus from soy lecithin; no isolates exhibited P solubilization capacity in medium supplemented with iron phosphate. Acid phosphatase activity was detected in 65% of the isolates; Aneurinibacillus sp. and Lysinibacillus sp. isolates presented with the best solubilization indexes. All of the assessed isolates exhibited a capacity to reduce the potential of hydrogen in liquid medium supplemented with tricalcium phosphate. Isolate EB. 78 (Bacillus sp.) exhibited P solubilization capacity in solid media when Ca3(PO4)2 and soy lecithin were used as P sources; this isolate significantly reduced the pH of the liquid medium and exhibited acid phosphatase activity. The results of the present study highlight isolates that exhibit variations in their capacity to solubilize P. These isolates should be used in future tests to assess their field performance.

ABSTRACT The phenological growth stages of various species of monocotyledonous and dicotyledonous plants can be uniformly coded using the Biologische Bundesanstalt, Bundessortenamt, und Chemische Industrie (BBCH) scale. The aim of the present study was to determine the duration of different phenological stages and the temperature requirements of the sugar-apple, Annona squamosa, during two crop cycles in the semiarid region of Brazil. Phenological stages were divided into eight of ten possible principal stages: (0) bud development, (1) leaf development, (3) shoot/branch development, (5) inflorescence emergence, (6) flowering, (7) fruit development, (8) fruit maturity and (9) senescence and the beginning of dormancy. The phenological cycle of the sugar-apple from having closed leaf buds to the fruit ripening stage lasted 149 and 164 days with temperature requirements of 1684.5 and 1786.7 degree days (DD) for the first and second crop cycles, respectively. The results provided important information that will inform the correct timing for crop management practices.

A estenospermia foi identificada em mutantes naturais de fruta do conde (Annona squamosa) e tem grande potencial de uso em programas de melhoramento genético. Até agora, não existem estudos detalhados sobre o desenvolvimento dos frutos aspérmicos desta espécie. O objetivo deste trabalho foi caracterizar a anatomia do fruto em desenvolvimento no mutante ‘Brazilian seedless’. Botões florais em pré-antese e frutos ao longo do desenvolvimento foram submetidos a técnicas usuais em anatomia vegetal. Os óvulos peculiares são unitegumentados, ortótropos e apresentam funículo longo. Existe evidência da fecundação como presença de embriões em início de desenvolvimento e proliferação de grãos de amido no saco embrionário. No entanto, os embriões e o saco embrionário degeneram, o que não afeta o desenvolvimento do pericarpo. Não ocorre aborto de óvulos e o perisperma, formado a partir das camadas periféricas do nucelo, preenche a cavidade deixada pelo saco embrionário. No fruto maduro ocorrem numerosas e pequenas sementes estéreis com abundante perisperma, porém, com tegumento não lignificado e restrito à região micropilar. A maioria das células do perisperma são vivas e têm aparência de serem metabolicamente ativas na periferia. A estenospermia leva a formação de sementes estéreis em A. squamosa e o perisperma possivelmente tem papel determinante no desenvolvimento do fruto.

Stenospermy was identified in naturally occurring sugar-apple (Annona squamosa) mutants with great potential for use in genetic improvement programs. However, to date, there have been no detailed studies of the development of aspermic fruit in this species. The aim of the present study was to characterize the anatomy of developing fruit in the ‘Brazilian Seedless’ mutant. Flower buds in pre-anthesis and developing fruits were subjected to common plant anatomy techniques. The abnormal ovules are unitegmic and orthotropic and have a long funiculus. There is evidence of fertilization, including the presence of embryos in early development and the proliferation of starch grains in the embryo sac. However, the embryos and embryo sac degenerate, although this does not affect pericarp development. Ovule abortion does not occur. The perisperm, which is formed from the peripheral layers of the nucellus, fills the cavity left by the embryo sac. The mature fruit contains numerous small sterile seeds with abundant perisperm and unlignified integument that is restricted to the micropylar region. The majority of perisperm cells are living and appear to be metabolically active in the periphery. Therefore, stenospermy leads to the formation of sterile seeds in A. squamosa, and the perisperm possibly play an important role in fruit development.

The genetic diversity of endophytic bacteria in banana 'Prata Anã' roots was characterized. Two hundred and one endophytic bacteria were isolated, 151 of which were classified as Gram-positive and 50 as Gram-negative. No hypersensitivity response was observed in any of the isolates. The rep-PCR technique generated different molecular profiles for each primer set (REP, ERIC and BOX). Fifty readable loci were obtained and all of the fragments were polymorphic. Amplified ribosomal DNA restriction analysis (ARDRA) of the isolates based on cleavage with four restriction enzymes yielded 45 polymorphic bands and no monomorphic bands. PCR amplified the nifH gene in 24 isolates. 16S rDNA sequencing of the 201 bacterial isolates yielded 102 high-quality sequences. Sequence analyses revealed that the isolates were distributed among ten bacterial genera (Agrobacterium, Aneurinibacillus, Bacillus, Enterobacter, Klebsiella, Lysinibacillus, Micrococcus, Paenibacillus, Rhizobium and Sporolactobacillus) and included 15 species. The greatest number of isolates belonged to the genus Bacillus. The bacteria identified in this study may be involved in promoting growth, phosphate solubilization, biological control and nitrogen fixation in bananas.