Micropropagation of banana by means of different morphogenetic routes is an important source of genetically uniform, pest-and disease-free planting materials of Musa spp. Morphogenesis of in vitro grown plants are affected by light quality, light quantity and photoperiod. Light-emitting diode (LED) lighting systems have several unique advantages, including their peak spectral output, which closely coincides with the red absorption peak of chlorophyll and the reported wavelengths for maximum photosynthetic efficiency. The present study was aimed to investigate the effect of two LED lighting treatments (white LED and deep red/white LED) compared to conventional fluorescent lamps on the stomata formation and chlorophyll (Chl) levels in micropropagated banana plantlets through organogenesis. Both LED lighting evaluated increased the levels of total Chl, Chl-a and Chl-b in banana in vitro plantlets, indicating no statistical difference between them, but being higher then plantlets subjected to fluorescent lamps. The number of stomata was also increased equally by both LED lighting treatments, indicating increased formation of stomata in both abaxial and adaxial leaf surfaces when compared to fluorescent lamps. Although all treatments presented 100 % survival in the acclimatization phase, LED lighting show promising for micropropagation of banana due to its known superior light quality, low energy consumed, little heat generated and long operating lifetime.

The complete plastome sequencing is an efficient option for increasing phylogenetic resolution and evolutionary studies, as well as may greatly facilitate the use of plastid DNA markers in plant population genetic studies. Merostachys and Guadua stand out as the most common and the highest potential utilization bamboos indigenous of Brazil. Here, we sequenced the complete plastome sequences of the Brazilian Guadua chacoensis and Merostachys sp. to perform full plastome phylogeny and characterize the occurrence, type, and distribution of SRRs using 20 Bambuseae species. The determined plastome sequence of Merostachys sp. and G. chacoensis is 136,334 and 135,403 bp in size, respectively, with an identical gene content and typical quadripartite structure consisting of a pair of IRs separated by the LSC and SSC regions. The Maximum Likelihood and Bayesian Inference analyses produced phylogenomic trees identical in topology. These trees supported monophyly of Paleotropical and Neotropical Bamboos clades. The Neotropical bamboos segregated into three well-supported lineages, Chusqueinae, Guaduinae, and Arthrostylidiinae, with the last two forming a well-supported sister relationship. Paleotropical bamboos segregated into two well-supported lineages, Hickeliinae and Bambusinae + Melocanninae. We identified 141.8 cpSSR in Bambuseae plastomes and an inferior value (38.15) for plastome coding sequences. Among them, we identified 16 polymorphic SSR loci, with number of alleles varying from 3 to 10. These 16 polymorphic cpSSR loci in Bambuseae plastome can be assessed for the intraspecific level of polymorphism, leading to innovative highly sensitive phylogeographic and population genetics studies for this tribe.

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Retrophyllum piresii (Podocarpaceae) is an endemic conifer species from the Brazilian Amazonian Region, and very few data related to ecological and genetic characteristics of this species are available. Plastome sequencing is an efficient tool to understand enigmatic and basal phylogenetic relationships at different taxonomic levels, as well as to probe the structural and functional evolution of plants. Usually, the plastome of photosynthetic land plants is quadripartite, with two copies of the inverted repeats (IRs) separating the small and large single-copy regions. However, in gymnosperms, IR can vary from large in size to completely absent, being constituted principally by transfer RNA (tRNA) genes, or a part of sequence of other genes. Here, we sequenced and characterized the complete plastome of R. piresii. This plastome was determined to be 133,291 bp (~480-fold coverage), presenting a total of 120 identified genes, of which 118 were single copy and two genes, trnN-GUU and trnD-GUC, were found to be duplicated and occurring as inverted and directed repeat (DR) sequences, respectively. These repeated regions presented recombinationally active sites, resulting in an IR-mediated inversion and a DR-mediated deletion. However, the isoform resulted from DR-mediated deletion may result in unviable plastome, with deletion of photosynthetic and expression machinery-related genes.

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