Gluconacetobacter diazotrophicus is a diazotrophic endophytic bacterium that promotes the growth and development of several plant species. However, the molecular mechanisms activated during plant response to this bacterium remain unclear. Here, we used the RNA-seq approach to understand better the effect of G. diazotrophicus PAL5 on the transcriptome of shoot and root tissues of Arabidopsis thaliana. G. diazotrophicus colonized A. thaliana roots and promoted growth, increasing leaf area and biomass. The transcriptomic analysis revealed several differentially expressed genes (DEGs) between inoculated and non-inoculated plants in the shoot and root tissues. A higher number of DEGs were up-regulated in roots compared to shoots. Genes up-regulated in both shoot and root tissues were associated with nitrogen metabolism, production of glucosinolates and flavonoids, receptor kinases, and transcription factors. In contrast, the main groups of down-regulated genes were associated with pathogenesis-related proteins and heat-shock proteins in both shoot and root tissues. Genes encoding enzymes involved in cell wall biogenesis and modification were down-regulated in shoots and up-regulated in roots. In contrast, genes associated with ROS detoxification were up-regulated in shoots and down-regulated in roots. These results highlight the fine-tuning of the transcriptional regulation of A. thaliana in response to colonization by G. diazotrophicus PAL5.

This study aimed to evaluate the effects of cryoprotectant agents on Passiflora eichleriana, Passiflora crystallina and Passiflora nitida seeds undergoing cryopreservation. The experiment was conducted with non-cryoprotected or non-cryopreserved seeds (control), cryopreserved seeds without cryoprotectant and cryopreserved seeds treated with the following cryoprotectants: 1.73, 2.28, 2.60 or 2.71 mol glycerol; 0.37, 0.46, 0.54 or 0.61 mol sucrose; or 0.37, 0.72, 1.04 or 1.35 mol dimethylsulfoxide (DMSO). After treatment, the seeds were cryopreserved in liquid nitrogen (LN₂) for 7 days and then defrosted in 37°C water for 5 min. The seeds were submitted to germination and vigor tests consisting of four replicates of 50 seeds. Percentage of germination (PE) and germination velocity index, percentage of emergence velocity index, shoot and root length, and shoot and root dry mass were evaluated. After cryopreservation, all of germination and vigor values were higher without the use of cryoprotectants. The cryoprotectant glycerol had a deleterious effect on seed viability and vigor for all Passiflora species. Glycerol inhibit seedling emergence and concentrations higher than 2.60 mol seed germination on P. cristalina. Higher concentrations of DMSO decrease seed viability and vigor in P. crystalina and P. nitida.

Hancornia speciosa Gomes, popularly known as mangabeira, is a fruit tree belonging to the Apocynaceae family, native to the Brazilian Cerrado. The fruit is widely used by the local population as an alternative source of income. Limited information is available about this species, which increases the difficulty of conserving its genetic resources and exploiting mangabeira as an economic resource. The objective of this research was to evaluate the genetic diversity and genetic structure of H. speciosa from Chapada dos Guimarães. Twenty-four trees and ten inter simple sequence repeats (ISSR) primers were evaluated. Of the 57 bands obtained, 33 (57.89%) presented polymorphism. The analysis using Structure defined two different clusters (K = 2), which were consistent with the unweighted pair group method with arithmetic mean (UPGMA) clustering analysis. The number of observed alleles (Na = 1.58), number of effective alleles (Ne = 1.29), Nei’s genetic distance (He = 0.18) and Shannon index (I = 0.27) were considered low among the population. The analysis of molecular variance (AMOVA) revealed that the variability within the cluster (83.39%) was higher than among clusters (16.61%). ISSR primers proved effective for detection of genetic polymorphism in H. speciosa, and could be utilized for strategies that aim at conservation, plant breeding programs, and commercial use.

Crioprotetores na criopreservação de sementes de Passiflora mucronata Lam