Pollination effectiveness was evaluated for pollen (pollinia) from two Dendrobium hybrids, ‘Sena Red’ and ‘Mini WRL’, submitted to cryopreservation using a vitrification protocol. Parameters evaluated included pollinia exposure to a previtrification solution (PVS2) under ice (0 °C) or room (27 ± 2 °C) temperatures from 1 to 4 hours before cryopreservation (LN). On removal from cryopreservation, pollinia were used to pollinate flowers of the same hybrids to verify viability and germination. All pollinia showed high percentages of germination (greater than 80%) after crosses were performed, except for pollinia from Dendrobium ‘Sena Red’ submitted to 3 hours of precooling (0 °C) in PVS2 followed by LN (60%) and for pollinia submitted to PVS2 for 3 hours at room temperature with no precooling (70%). Capsules were formed for both hybrids and seeds were successfully produced. The seed viability test revealed high viability (90% to 95%) for all treatments for both hybrids. Seeds observed under a microscope contained well-formed embryos and no abnormalities were identified. Seeds from all treatments germinated. Germinating seeds developed into healthy seedlings with well-formed leaves and roots. Cryopreservation of pollinia was successfully accomplished either by direct storage in liquid nitrogen without cryoprotection treatments or by using a PVS2 vitrification protocol.

Each year, approximately 170 million metric tons of chemical fertilizer are consumed by global agriculture. Furthermore, some chemical fertilizers contain toxic by-products and their long-term use may contaminate groundwater, lakes, and rivers. The use of plant growth-promoting bacteria may be a cost-effective strategy for partially replacing conventional chemical fertilizers, and may become an integrated plant nutrient solution for sustainable crop production. The main direct bacteria-activated mechanisms of plant growth promotion are based on improvement of nutrient acquisition, siderophore biosynthesis, nitrogen fixation, and hormonal stimulation. The aim of this study was to isolate and identify bacteria with growth-promoting activities from sugarcane. We extracted the bacterial isolate SCB4789F-1 from sugarcane leaves and characterized it with regard to its profile of growth-promoting activities, including its ability to colonize Arabidopsis thaliana. Based on its biochemical characteristics and 16S rDNA sequence analysis, this isolate was identified as Pantoea ananatis. The bacteria were efficient at phosphate and zinc solubilization, and production of siderophores and indole-3-acetic acid in vitro. The isolate was characterized by Gram staining, resistance to antibiotics, and use of carbon sources. This is the first report on zinc solubilization in vitro by this bacterium, and on plant growth promotion following its inoculation into A. thaliana. The beneficial effects to plants of this bacterium justify future analysis of inoculation of economically relevant crops.

Passion fruit (Passiflora edulis) is a fruit species of great relevance for Brazilian economy. However, it is highly susceptible to the Cowpea aphid-borne mosaic virus (CABMV). The species P.setacea, on the other hand, is resistant to the disease. The present study aimed to identify CABMV-resistant P. setacea genotypes for the introgression of genes into sour passion fruit genetic breeding programs. The seeds of passion fruit genotypes were germinated in vitro in MS culture medium. The seedlings were acclimatized in a growth chamber at the temperature of 27 ± 2ºC, photoperiod of 16:8 hours and 80% of relative humidity. Thirty plants of each genotype were mechanically inoculated with extract prepared from leaves collected from passion fruit plants with symptoms of CABMV for the assessment of resistance to CABMV. The severity of leaf symptoms was evaluated by means of a grading scale of visual signs. After the visual evaluation and identification of the asymptomatic genotypes of P. setacea, the PTA-ELISA test was carried out for 30 selected genotypes. According to the visual evaluation, all P. setacea genotypes were highly resistant to CABMV, while the P. edulis genotypes were highly susceptible. Out of the 30 genotypes selected, only PsRJ 4 was considered susceptible by PTA-ELISA. The other genotypes of P. setacea were considered resistant and present great potential for use in passion fruit genetic breeding programs.