BackgroundCurrently, the technology called Clearfield® is used in the development of crops resistant to herbicides that inhibit the enzyme acetohydroxy acid synthase (AHAS, EC 2.2.1.6). AHAS is the first enzyme of the biosynthetic pathway that produces the branched-chain of the essential amino acids valine, leucine, and isoleucine. Therefore, multiple copies of the AHAS gene might be of interest for breeding programs targeting herbicide resistance. In this work, the characterization of the AHAS gene was accomplished for the Chenopodium quinoa Regalona-Baer cultivar. Cloning, sequencing, and Southern blotting were conducted to determine the number of gene copies.ResultsThe presence of multiple copies of the AHAS gene as has been shown previously in several other species is described. Six copies of the AHAS gene were confirmed with Southern blot analyses. CqHAS1 and CqAHAS2 variants showed the highest homology with AHAS mRNA sequences found in the NR Database. A third copy, CqAHAS3, shared similar fragments with both CqAHAS1 and CqAHAS2, suggesting duplication through homeologous chromosomes pairing.ConclusionsThe presence of multiple copies of the gene AHAS shows that gene duplication is a common feature in polyploid species during evolution. In addition, to our knowledge, this is the first report of the interaction of sub-genomes in quinoa

Quinoa (Chenopodium quinoa Willd) is a dicotyledonous annual species belonging to the family Amaranthaceae, which is nutritionally well balanced in terms of its oil, protein and carbohydrate content. Targeting-induced local lesions in genomes (the TILLING strategy) was employed to find mutations in acetolactate synthase (AHAS) genes in a mutant quinoa population. The AHAS genes were targeted because they are common enzyme target sites for five herbicide groups. Ethyl methane sulfonate (EMS) was used to induce mutations in the AHAS genes; it was found that 2% EMS allowed a mutation frequency of one mutation every 203 kilobases to be established. In the mutant population created, a screening strategy using pre-selection phenotypic data and next-generation sequencing (NGS) allowed identification of a mutation that alters the amino acid composition of this species (nucleotide 1231 codon GTT→ATT, Val→Ile); however, this mutation did not result in herbicide resistance. The current work shows that TILLING combined with the high-throughput of NGS technologies and an overlapping pool design provides an efficient and economical method for detecting induced mutations in pools of individuals.

Cocoa (Theobroma cacao L.) is one of the most important crops in Ecuador; however, its production is limited, among other factors, by the crop nutrition. The objective of this research was to determine the effect of the combined nitrogen, phosphorus and potassium fertilization on soil characteristics, growth traits and quality of shoots and fruits in cocoa. The experiment was carried out under a completely randomized design with factorial arrangement, with three factors, N, P and K, and two levels by factor (with and without fertilization), plus an absolute control without fertilization. The chemical characteristics of the soil, including pH, N, P, K, Ca and Mg content were evaluated. New shoots were also evaluated by measuring its number, length, leaf area, and growth rate. In the fruits, the weight, length and growth rate were measured. In shoots and fruits, quality traits including dry matter, fiber, ash, lipids and protein content were measured. Significant interactions of the applied nutrients were found, which increased the content of P and K, and decreased Ca and Mg of the soil. The N fertilization alone did not affect the growth of the shoots and foliar area. The interactions of the primary elements significantly increased the dry matter and fiber of the shoots, while the growth and quality of fruits were not modified.

Cocoa is a crop in increasing demand and cultivated worldwide. However, basic information concerning the movement of nutrients in leaves over time is still unknown, and methods to find an optimal time to collect a sample are still ambigu-ous. The present work focused on describing the movement of foliar nutrients (N, P, K, Ca and Mg) in productive 5-year-old cocoa clone CCN51 plants at the same dose of 114.8 kg ha-1 under different sources of nitrogen fertilization (Urea, calcium ni-trate, ammonium sulfate and a control without application). Samples were taken from the time the leaf reached 70% of its total expansion until 10 months of age. The results indicated that the contents of N, Ca and Mg increased as the leaf grew, remained stable between 116 and 158 days of shoot emergence (DSE) and then decreased at the beginning of the leaf senescence period. While the K and P con-tents decrease from the beginning of the trial until 158 DSE where they are stable until the final stage of leaf life. Around 110 to 120 DSE, the leaves of cocoa CCN51 show a more stable nutritional content, a period in which samples can be collected for leaf analysis.

The research was carried out in Mocache, province of Los Ríos, where three experimental corn trials were established, one on the property of Mr. Fortunato Cedeño Diaz, located in the John F. Kennedy sector, and two located on the “La María” Campus of the Quevedo State Technical University (UTEQ), with the purpose of evaluating the effect of different planting distances of a commercial hybrid (hybrid ADV-9139) and a creole variety (Creole variety S/N) of corn during the dry and rainy seasons, in order to define optimal planting distances to achieve better yields. A completely randomized design (CRD) with a unifactorial arrangement was applied, with six treatments composed of a combination of two variables: varieties and planting distances. The first consisted of two genotypes: hybrid ADV-9139 and a creole variety S/N, and the second consisted of distances of 0.6 times 0.2 m; 0.7 × 0.2 m and 0.8 × 0.2 m. Each of these treatments had four replications. The results showed little influence of distances on plant height, stem diameter and ear insertion height. Regarding productive parameters such as yield, T4 (Hybrid ADV 9139 + 0.6 X 0.2) and T5 (Hybrid ADV 9139 + 0.7 X 0.2) stood out in trials 1 and 3, while only T4 stood out in trial 2.