Anna Cristina Lanna

Atributos biológicos do solo sob influência da cobertura vegetal e do sistema de manejo

The objective of this work was to evaluate the effects of cover crops and direct and conventional tillage systems on soil biological attributes when cultivated with dry bean in winter under sprinkle irrigation. The experiment was conducted in Santo Antonio de Goias, GO, Brazil, in a clayey Rhodic Haplustox. Cover crops were cultivated annually in the summer since 2001, using Brachiaria brizantha, Cajanus cajan, Pennisetum glaucum, Panicum maximum, sorghum, Stylosanthes guianensis, brachiaria in association with corn, and native vegetation as reference. In 2005, 60 days after cutting the cover crops, BRS Valente bean cultivar, under irrigation, was cultivated. Sowing was performed on June 16, 2005 and the harvest on September 19, 2005. Soil samples were collected to a depth of 0-10 cm, in November 2004 (before cover crops planting), June 2005 (before dry bean planting) and July 2005 (at dry bean flowering). Evaluations of basal respiration, carbon and nitrogen of microbial biomass, microbial/organic carbon ratio, microbial/total nitrogen ratio and metabolic quotient were performed. Soil biological attributes were influenced by cover crops, soil management and sampling time.

A Proposed Risk Assessment Method for Genetically Modified Plants

An essential step in the development of products based on genetically modified plants (GMPs) is an assessment of safety, including an evaluation of the potential impact of the crop and practices related to its cultivation on the environment and human or animal health. The purpose of this safety assessment is to compare information about the GMP with that from a non-GM crop. However, at present this risk analysis may be faulty because there is no widely accepted and specific risk assessment method to evaluate GMPs that uses quantifiable parameters and allows for a comparative analysis among different technologies. This paper introduces a risk analysis method that focuses on the identification and evaluation of risks associated with the field release and cultivation of GMPs. Two tools bolster this proposed risk assessment method: (1) worksheets to compile Evidence of Risks, and (2) a Matrix of Assessment. The first tool identifies potential hazards related to the use of a specific GMP. This preformatted worksheet assigns values to the level of risk and its significance in terms of the activity to be developed. The second tool provides a structure to observe the potential hazards that illustrates what approach supports the use of GMPs in a manner as safe as any other traditional technology. To better understand this proposed risk assessment method, it is presented in a digital format (www.cnpma.embrapa.br/forms/gmp_ram.php3) (GMP-RAM v.1.1. software) where the two tools are linked so that the user can fill in the worksheets and automatically observe the results in the matrix. Compared to current processes, this proposed method represents a less subjective and more transparent process for risk assessment.

In-depth genome characterization of a Brazilian common bean core collection using DArTseq high-density SNP genotyping

BackgroundCommon bean is a legume of social and nutritional importance as a food crop, cultivated worldwide especially in developing countries, accounting for an important source of income for small farmers. The availability of the complete sequences of the two common bean genomes has dramatically accelerated and has enabled new experimental strategies to be applied for genetic research. DArTseq has been widely used as a method of SNP genotyping allowing comprehensive genome coverage with genetic applications in common bean breeding programs.ResultsUsing this technology, 6286 SNPs (1 SNP/86.5 Kbp) were genotyped in genic (43.3%) and non-genic regions (56.7%). Genetic subdivision associated to the common bean gene pools (K = 2) and related to grain types (K = 3 and K = 5) were reported. A total of 83% and 91% of all SNPs were polymorphic within the Andean and Mesoamerican gene pools, respectively, and 26% were able to differentiate the gene pools. Genetic diversity analysis revealed an average HE of 0.442 for the whole collection, 0.102 for Andean and 0.168 for Mesoamerican gene pools (FST = 0.747 between gene pools), 0.440 for the group of cultivars and lines, and 0.448 for the group of landrace accessions (FST = 0.002 between cultivar/line and landrace groups). The SNP effects were predicted with predominance of impact on non-coding regions (77.8%). SNPs under selection were identified within gene pools comparing landrace and cultivar/line germplasm groups (Andean: 18; Mesoamerican: 69) and between the gene pools (59 SNPs), predominantly on chromosomes 1 and 9. The LD extension estimate corrected for population structure and relatedness (r2SV) was ~ 88 kbp, while for the Andean gene pool was ~ 395 kbp, and for the Mesoamerican was ~ 130 kbp.ConclusionsFor common bean, DArTseq provides an efficient and cost-effective strategy of generating SNPs for large-scale genome-wide studies. The DArTseq resulted in an operational panel of 560 polymorphic SNPs in linkage equilibrium, providing high genome coverage. This SNP set could be used in genotyping platforms with many applications, such as population genetics, phylogeny relation between common bean varieties and support to molecular breeding approaches.

Physiological characterization of common bean (Phaseolus vulgaris L.) under abiotic stresses for breeding purposes

In the Brazilian wet and dry seasons, common beans (Phaseolus vulgaris L.) are grown under rainfed conditions with unexpected episodes of drought and high temperatures. The objective of this study was to evaluate the physiological mechanisms associated with drought adaptation traits in landraces and line/cultivars of beans from the Andean and Mesoamerican gene pools. Twenty-five genotypes, contrasting in terms of drought tolerance, were evaluated in a phenotyping platform under irrigated and rainfed conditions. Agronomic and physiological parameters such as grain yield, shoot structures, gas exchange, water potential, and osmotic adjustment were evaluated. The stress intensity was estimated to be 0.57, and the grain yield reduction ranged from 22 to 89%. Seven accessions, representative of the Andean and Mesoamerican germplasm (CF 200012, CF 240056, CF 250002, CF 900004, CNF 4497, CNF 7382, and SEA 5), presented superior performance in grain yield with and without stresses. The physiological responses under abiotic stresses were highly variable among the genotypes, and two Mesoamerican accessions (CF 200012 and SEA 5) showed more favorable adaptive responses. As the main secondary physiological traits, gas exchange and osmotic adjustment should be evaluated together with the grain yield to increase the selection efficiency of abiotic stresses-tolerant common bean lines.