Jacobo Arango

Biological nitrification inhibition activity in a soil-grown biparental population of the forage grass, Brachiaria humidicola

AimUtilization of biological nitrification inhibition (BNI) strategy can reduce nitrogen losses in agricultural systems. This study is aimed at characterizing BNI activity in a plant-soil system using a biparental hybrid population of Brachiaria humidicola (Bh), a forage grass with high BNI potential but of low nutritional quality.MethodsSoil nitrification rates and BNI potential in root-tissue were analyzed in a hybrid population (117), obtained from two contrasting Bh parents, namely CIAT 26146 and CIAT 16888, with low and high BNI activity, respectively. Observed BNI activity was validated by measuring archaeal (AOA) and bacterial (AOB) nitrifier abundance in the rhizosphere soil of parents and contrasting hybrids. Comparisons of the BNI potential of four forage grasses were conducted to evaluate the feasibility of using nitrification rates to measure BNI activity under field and pot grown conditions.ResultsHigh BNI activity was the phenotype most commonly observed in the hybrid population (72%). BNI activity showed a similar tendency for genotypes grown in pots and in the field. A reduction in AOA abundance was found for contrasting hybrids with low nitrification rates and high BNI potential.ConclusionBh hybrids with high levels of BNI activity were identified. Our results demonstrate that the microcosm incubation and the in vitro bioassay may be used as complementary methods for effectively assessing BNI activity. The full expression of BNI potential of Bh genotypes grown in the soil (i.e. low nitrification rates) requires up to one year to develop, after planting.

Current Issues in Cereal Crop Biodiversity

The exploration, conservation, and use of agricultural biodiversity are essential components of efficient transdisciplinary research for a sustainable agriculture and food sector. Most recent advances on plant biotechnology and crop genomics must be complemented with a holistic management of plant genetic resources. Plant breeding programs aimed at improving agricultural productivity and food security can benefit from the systematic exploitation and conservation of genetic diversity to meet the demands of a growing population facing climate change. The genetic diversity of staple small grains, including rice, maize, wheat, millets, and more recently quinoa, have been surveyed to encourage utilization and prioritization of areas for germplasm conservation. Geographic information system technologies and spatial analysis are now being used as powerful tools to elucidate genetic and ecological patterns in the distribution of cultivated and wild species to establish coherent programs for the management of plant genetic resources for food and agriculture.

The Effect of Pre-Harvest Methyl Jasmonate Treatment on the SelectedVolatile Compounds and Endogenous Hormones Contends in the Pulp ofGrape Berries

Grapevine is one of the most valued and widely cultivated fruit crop worldwide, with their pleasant flavor and valuable health effects. During the consequent ripening at ambient temperature, the volatile compounds of table grape often decreased, to affect their sensory evaluation. The development of new and effective methods to increase the volatile compounds of berries is necessary. Present study was carried out to investigate the pre-harvest methyl jasmonate (MeJA) treatment on the selected volatile compounds and endogenous hormones content from ‘Shine Muscat’ berries pulp. The results indicated that, pre-harvest application of MeJA (0.1 mM or 0.01 mM) on grape berries generally enhanced the production of terpenes, like nerol, linalool, alpha-terpineol; While some C6 compounds were reduced, such as (E)-2-hexenol, hexanol, (Z)-3-hexenol, hexanal and (E)-2-hexenal. The endogenous hormones like IAA (indole acetic acid), ABA (abscisic acid) and JA (jasmonate acid) content were also changed after MeJA treatment. We also observed that MeJA palys a key role in fruit endogenous hormones level and volatile compounds by increasing the expression level of several related genes, such as aroma-related genes Vvter, Vv-syn and hormone-related genes VvOPR3, VvAuI, VvEth, VvNCED1. We hypothesize that, MeJA as an effective elicitor affects the volatile compounds by altering endogenous hormones level in berries pulp of ‘Shine Muscat’.

Evidence of Epigenetic Mechanisms Affecting Carotenoids

Epigenetic mechanisms are able to regulate plant development by generating non-Mendelian allelic interactions. An example of these are the responses to environmenal stimuli that result in phenotypic variability and transgression amongst important crop traits. The need to predict phenotypes from genotypes to understand the molecular basis of the genotype-by-environment interaction is a research priority. Today, with the recent discoveries in the field of epigenetics, this challenge goes beyond analyzing how DNA sequences change. Here we review examples of epigenetic regulation of genes involved in carotenoid synthesis and degradation, cases in which histone- and/or DNA-methylation, and RNA silencing at the posttranscriptional level affect carotenoids in plants.