Microbiomes of Velloziaceae from phosphorus-impoverished soils of the campos rupestres, a biodiversity hotspot.

The rocky, seasonally-dry and nutrient-impoverished soils of the Brazilian campos rupestres impose severe growth-limiting conditions on plants. Species of a dominant plant family, Velloziaceae, are highly specialized to low-nutrient conditions and seasonal water availability of this environment, where phosphorus (P) is the key limiting nutrient. Despite plant-microbe associations playing critical roles in stressful ecosystems, the contribution of these interactions in the campos rupestres remains poorly studied. Here we present the first microbiome data of Velloziaceae spp. thriving in contrasting substrates of campos rupestres. We assessed the microbiomes of Vellozia epidendroides, which occupies shallow patches of soil, and Barbacenia macrantha, growing on exposed rocks. The prokaryotic and fungal profiles were assessed by rRNA barcode sequencing of epiphytic and endophytic compartments of roots, stems, leaves and surrounding soil/rocks. We also generated root and substrate (rock/soil)-associated metagenomes of each plant species. We foresee that these data will contribute to decipher how the microbiome contributes to plant functioning in the campos rupestres, and to unravel new strategies for improved crop productivity in stressful environments.

Cloreto de potássio e fosfato de sódio na multiplicação in vitro de amoreira-preta cv. Tupy / Effect of KCl and NaH2PO4.H2O on in vitro multiplication of blackberry cv. Tupy

A micropropagação da amoreira-preta pode gerar plantas livres de vírus e em curto espaço de tempo. Com o objetivo de aprimorar técnicas de micropropagação de amoreira-preta cv. Tupy (Rubus spp.), segmentos nodais com cerca 2 cm e 2 gemas axilares, oriundos de plantas pré estabelecidas in vitro, foram excisados e inoculados em meio de cultura MS, suplementado com diferentes concentrações de fosfato de sódio (0, 125, 250, 500 e 1000 mg L-1) e de cloreto de potássio (0, 125, 250, 500 e 1000 mg L-1). O pH foi ajustado para 5,8 antes da adição de 6 g L-1 de ágar e da autoclavagem a 121ºC e 1 atm por 20 minutos. Após a inoculação, os explantes foram transferidos para sala de crescimento a 25 ± 1ºC, irradiância de 35 mmol m-2 s-1 e fotoperíodo de 16 horas, onde permaneceram por 60 dias. O delineamento experimental utilizado foi inteiramente casualisado, utilizando-se de quatro repetições constituídas de três tubos de ensaio contendo um explante cada. O número de brotos e o comprimento da parte aérea das plantas foi menor em função de maiores concentrações de cloreto de potássio. Melhores resultados foram obtidos na ausência de KCl e na presença de fosfato de sódio, principalmente para comprimento e matéria fresca da parte aérea.

The micropropagation of blackberry can generate virus-free plants in short time. In order to improve micropropagation techniques of blackberry cv. Tupy (Rubus spp.), nodal segments with 2 cm length and 2 axillary buds originating from plants in vitro were excised and inoculated in MS culture medium, supplemented with different concentrations of sodium phosphate (0, 125, 250, 500 and 1000 mg L-1) and potassium chloride (0, 125, 250, 500 and 1000 mg L-1). The pH was adjusted to 5.8 before the addition of 6 g L-1 agar and sterilization at 121ºC and 1 atm for 20 minutes. After the inoculation, the explants were transferred to growth room at 25 ± 1ºC, 35 mmol m-2 s-1 irradiance and photoperiod of 16 hours, where they stayed for 60 days. The experiment was arranged in a completely randomized design, using four repetitions with 12 plants each. Number of sprouts and length of the aerial part of plants were smaller, due to larger concentrations of potassium chloride. Better results were obtained in the absence of KCl, and in the presence of sodium phosphate, mainly for length and fresh weight of the aerial part.