Scielo RSS <![CDATA[Chilean journal of agricultural research]]> vol. 77 num. 1 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Morphological and genetic characterization among wild populations of copao ( <em>Eulychnia acida</em> Phil.), cactus endemic to Chile]]> ABSTRACT There are endemic cacti species in the North of Chile with edible fruits and a fledgling productive potential, with unknown degree diversity. Low diversity compromises the ability of populations to evolve and reduces their chances of survival under environmental changes. Copao (Eulychnia acida Phil.), a cactus endemic to Chile that grows in the Coquimbo Region (30° S lat) and able to bear fruit in water stress conditions, were morphologically characterized using descriptors of other columnar cacti at three different locations where it usually grows wild. Five inter simple sequence repeat (ISSR) primers, which were reported for other cacti that produced replicable and informative amplifications, were selected for the genetic characterization. Statistical analysis was performed to describe the diversity of this species and morphological and genetic results compared each other. High variation was observed between and within the evaluated populations for parameters of central tendency, dispersion, and univariate statistical analysis of the morphological traits. Principal component analysis showed that 73% of the population variation at the three locations could be explained by the first three principal components with 34%, 22%, and 17% of the observed variation, respectively. The five ISSR primers generated 7 to 11 polymorphic bands with a band range between 100 and 1517 bp. The polymorphic information content (PIC) averaged 0.75, which suggests high diversity between and within populations. Consensus of 85% existed between the selected descriptors and the ISSR markers, which points them out as suitable tools to analyze diversity in this species. <![CDATA[Assessment of the genetic diversity and population structure in temperate <em>japónica</em> rice germplasm used in breeding in Chile, with SSR markers]]> ABSTRACT Rice Breeding Program (RBP) of the Instituto de Investigaciones Agropecuarias (INIA) at Chillán, Chile, has a rice (Oryza sativa L.) germplasm collection that consists of 1200 accessions, mainly temperate japónica rice accessions, well adapted to the local conditions. Most of the new introduced accessions adapt very poorly to Chilean agroecological conditions because of requirements of long days and cold tolerance. The objectives of this study were to use microsatellites to evaluate level of polymorphism of a representative sample of this collection and determine its genetic diversity and relationships with cultivated germplasm from different geographical origin. A total of 249 genotypes were analyzed with 30 selected polymorphic microsatellites. Total number of alleles scored across 249 genotypes was 183 with an overall mean of 6.1 alleles per locus, ranging 2-14. The mean major allele (most common) frequency was 0.61 and mean minor allele frequency was 0.028. The overall mean gene diversity across 30 SSR loci was 0.52. Mean heterozygosity was 0.01, and mean polymorphism information content (PIC) value was 0.47. The accessions were organized by structure analysis into three main groups and revealed a fairly consistent genetic relationship with dendrogram and Principal Coordinates Analysis (PCoA). The temperate japonica accessions can be further subdivided into three subpopulations where long and short grain Chilean varieties were grouped into different clusters. The three populations showed different level of admixture, admixture probably due to previous breeding work through years. Results indicate that polymorphism levels of Chilean rice temperate japonica collection has similar magnitude as temperate japonica germplasm reported in the literature. <![CDATA[Environmental effect on genetic gains and its impact on bread-making quality traits in Brazilian spring wheat]]> ABSTRACT In wheat (Triticum aestivum L.) several studies have reported genetic gain for grain yield over the years. However, studies on wheat bread-making quality are scarce. Our objective was to estimate the progress due to genetic and environmental components in wheat bread-making quality parameters. In addition, we aimed to examine trends in historical cultivars and associate traits performance with geographical parameters. We used data from multi-environment trials (MET) represented by eight years (2005-2012) and 458 genotypes, including lines and commercial cultivars (controls). We determined the genetic progress by the contrasts between genotypes assessed in each biennium, excluding the year effect. This effect is previously estimated by existing variation among common genotypes. Genotype replacement rate was 52% and reflects the dynamism of the breeding program to develop better genotypes in terms of bread-making quality. The genetic progress estimated for gluten strength (W) was 1.30% yr-1. The progress in W demonstrated to be partly counterbalanced by the environmental effect (-0.78% yr-1). We observed disequilibrium tendency in relationship between tenacity and extensibility (P/L ratio) as a consequence of searching for lines with high W. Analysis showed that P/L ratio can be reduced in responses to the increase in latitude of the location. Environmental and genetic effects on the traits variation were discussed. <![CDATA[Phenotypic diversity in lima bean landraces cultivated in Brazil, using the Ward-MLM strategy]]> ABSTRACT Lima bean (Phaseolus lunatus L.) is an important source of protein for people as it contributes all of the essential amino acids necessary for humans. In Brazil, lima bean has a great relevance, mainly in the Northeast, where it is an alternative income in addition to a food source. It has a high degree of phenotypic variation for seed traits, which are important for understanding the genetic diversity and origin of this crop. We aimed to characterize 166 accessions of cultivated lima bean from Brazil using qualitative and quantitative descriptors through the Ward-MLM (Modified Location Model) in order to analize the organization of the genetic diversity and the origin of this germplasm. High genetic variability was detected and seed length and width characteristics were the main contributors to genetic divergence among the accessions. Results showed the presence of accessions with characteristics typical of the Mesoamerican and Andean gene pools, and another group with intermediate characteristics of these two gene pools. Our results will be useful to breeding programs, since currently there is little information on the genetic diversity and the origin of the lima bean landraces cultivated in Brazil. <![CDATA[Molecular characterization of red clover genotypes utilizing microsatellite markers]]> ABSTRACT Genetic resources of red clover (Trifolium pratense L.) are the basis for the improvement of this important forage legume. The objective of this study was microsatellite characterization of the accessions from the collection of the Institute of Field and Vegetable Crops in Novi Sad, Serbia. Molecular evaluation of 46 red clover genotypes was performed by applying the set of 14 primer pairs of microsatellite markers. These primer pairs amplified a total of 187 alleles, with an average of 13.36 alleles per locus and average polymorphism information content (PIC) value was 0.306. The minimum values of Dice genetic distances based on polymorphism of microsatellite markers were found among genotypes NCPGRU2 and NCPGRU5 (0.311) and the highest values of genetic distances were determined for a couple of genotypes Violeta and BGR2 (0.933). The average genetic distance between all pairs of genotypes amounted 0.587. The results of the principal coordinate analysis (PCoA) were consistent with the results obtained on the basis of cluster analysis, except that the PCoA allocated another four genotypes. There was no relationship between groups of genotypes formed by the use of cluster analyses and PCoA with their geographical origin. Analysis of molecular variance of 46 red clover genotypes by the status and ploidy level was significant, but it also suggested a weak genetic differentiation of groups formed on the basis of those characteristics. Observed groups of genotypes, according to the cluster analyses and PCoA of microsatellite data, could be used in future breeding programs for the selection of germplasm. <![CDATA[Genetic diversity of elephant grass (<em>Cenchrus purpureus</em> [Schumach.] Morrone) for energetic production based on quantitative and multi-category traits]]> ABSTRACT Elephant grass (Cenchrus purpureus (Schumach.) Morrone) has been used as an alternative source of energy. It is widely cultivated in Brazil, however it needs genotypes adapted to different ecosystems of the country. The knowledge of genetic diversity allows the identification of genotypes that can be used in breeding programs. Thus, this study aimed to evaluate the diversity among 85 genotypes of elephant grass by Tocher's clustering method and by the unweighted pair group method with arithmetic averages (UPGMA), using quantitative and multi-category traits in 2 yr of evaluations. The experiment was implemented in the State Center for Research on Bioenergy and Waste Use at Pesagro-Rio, located in Campos dos Goytacazes, Rio de Janeiro, Brazil. Eighty-five elephant grass genotypes donated by the Active Elephant Grass Germplasm Bank of Embrapa Dairy Cattle, in Coronel Pacheco, Minas Gerais, Brazil, were included in the experiment. The experimental design was arranged as randomized blocks, with two replicates. Based on the quantitative traits, the 85 genotypes analyzed belonged to 17 groups according to Tocher's optimization method and to 13 groups when analyzed by UPGMA. For the qualitative traits, however, the genotypes formed 10 groups for both methods. Therefore, the multivariate technique indicated genetic divergences among the genotypes and allowed the formation of similarity groups by Tocher's optimization and UPGMA methods for both the quantitative and qualitative traits. <![CDATA[Selection of resistant rootstocks to <em>Meloidogyne enterolobii</em> and <em>M. incognita</em> for okra <em>(Abelmoschus esculentus</em> L. Moench)]]> ABSTRACT The okra (Abelmoschus esculentus L. Moench) is one of the most important vegetables in the world and is a popular food item in many tropical and subtropical countries. Besides its cultivation for fresh consumption, okra also has potential industrial uses. Nonetheless, pests and diseases remain the most damaging factors affecting its crop yield. Among these, root-knot nematodes are the main pests limiting okra production. This study aimed to determine the responses of plant species of the Malvaceae family to Meloidogyne incognita and M. enterolobii root-knot nematodes, and to also assess the compatibility of the same with the okra commercial 'Colhe Bem IAC'. Resistance was evaluated using the reproduction factor in two commercial okra cultivars ('Colhe Bem IAC' and 'Santa Cruz 47'), five cotton (Gossypium hirsutum L.) plant genotypes (PRO 277, IAC 29-233, PR 136, IAC 24, and IAC 03-979), and vinagreira (Hibiscus sabdariffa L.) Other resistance-related traits measured were the percentage of healing, plant height, root length, rootstock stem diameter, scion stem diameter, number of leaves, total fresh weight, and fresh weight of the scion, rootstock, and root parts. While the cotton and vinagreira genotypes tested were resistant to both species of nematodes, okra cultivars were not. The okra, however, showed successful adaptation to grafting, which may offer an important physical resistance against attacks by root-knot nematodes, while vinagreira showed the greatest potential for use as rootstock for protecting okra crops. <![CDATA[Herbicides cross resistance of a tribenuron-methyl resistant <em>Capsella bursa-pastoris</em> (L.) Medik. population in wheat field]]> ABSTRACT Shepherd's purse (Capsella bursa-pastoris [L.] Medik.) is a troublesome dicot weed that occurs in major wheat (Triticum aestivum L.) production areas in China. Tribenuron-methyl failed to control shepherd's purse in some fields in Runan County, Henan Province. This study aimed to establish the cross-resistance pattern of a resistant (R) population and explore the potential target-site and non-target-site based resistance mechanisms. Acetohydroxyacid synthase (AHAS) gene sequencing revealed a single nucleotide change of CCT to CGT resulting in the Pro to Arg substitution at amino acid position 197 in resistant individuals. Compared with the susceptible (S) population, R population displayed high level resistance to tribenuron-methyl. Cross resistance patterns showed that the R population was high resistant to flucarbazone-Na; moderately resistant to florasulam; low resistant to pyrithiobac sodium and pyroxsulam, and sensitive to imazethapyr. The pretreatment of malathion reduced the 50% growth reduction (GR50) value of tribenuron-methyl by 29% in the R population, suggesting that target-site resistance and non-target-site resistance mechanisms were both present in tribenuron-methyl -resistance of shepherd's purse. This is the first report of the acetolactate synthase Pro197Arg mutation in shepherd's purse. <![CDATA[Reaction of melon genotypes to Didymella bryoniae (Fuckel) Rehm]]> ABSTRACT The cultivation of melon (Cucumis melo L.) in greenhouses has contributed to the increased incidence of fungal diseases, particularly gummy stem blight caused by Didymella bryoniae (Fuckel) Rehm. This disease is currently considered the main disease affecting this crop, causing conditions such as water soaked seedlings, and stem and fruit cankers, reducing productivity and fruit quality. Considering the importance of this disease, the aim of this study was to evaluate the reaction of different C. melo genotypes to D. bryoniae. Sixty-eight different melon genotypes were investigated. Two phenotyping assays were performed to investigate the resistance to the disease, following a randomized block design with four replicates. Subsequently, a new assay was conducted to validate the resistance of the genotypes selected in the previous step, using a randomized block design with three replicates. The plants were inoculated using the toothpick method, and resistance was evaluated according to a grading scale. Also, reaction classes and assay groups were used for classifying the resistance level of the genotype. The JAB-11 and JAB-20 strains were susceptible to the pathogen, as well as the commercial hybrids Louis F1 and Fantasy Fi. The hits AC-29, C160, Charentais Fom 1, PI 420145, PI 482398 and PI 532830 were resistant to D. bryoniae, and could become an important gene source for the development of resistant cultivars. <![CDATA[Re-watering: An effective measure to recover growth and photosynthetic characteristics in salt-stressed <em>Brassica napus</em> L.]]> ABSTRACT Salinity is one of major environmental problem which is limiting the agricultural production. This research was conducted to evaluate the effect of re-watering on Brassica napus L., and determination of an appropriate regime for dilution of salted water by studying photosynthetic and growth response of B. napus to salt stress and subsequent re-watering. Plants were treated with NaCl (Nc 2.5, Nc2: 5, Nc3: 10; g L-1); Na2SO4 (Ns 2.5, Ns2: 5, Ns3: 10; g L-1) and mixed salts treatments (M1: Nc1+ Ns3; M2: Nc3+ Ns1; M3: Nc2+ Ns2; g L-1) and 0 as control, followed by re-watering. In salt stress phase, maximum reduction in net photosynthetic rate (PN) was noted 79.54%, 80.72%, 84.54%, and 74.84% for Nc3, Ns3, M1 and M2, respectively, under high concentration levels. To maintain PN, carbonic anhydrase (CA) activity was stimulated and kept water status stable under low (Nc1 and Ns1) to medium concentration levels (Nc2, Ns2 and M3), and the decreases in PN under Nc2, Ns2 and M3 were 48.28%, 55.58% and 58.69%, respectively. However, during re-watering phase, growth and physiological parameters were recovered well due to regulation of CA activity under low to medium concentration levels. Relatively as compare to other stress levels more recovery in PN was found after re-watering under medium concentration levels, which were 44.94%, 53.45% and 63.04%, respectively. Though aimed at consideration of high production in B. napus, the best re-watering time was found to be when plants undergo medium concentration levels. Therefore, this study provides a new method for dilution of saline irrigation based on plant physiology. <![CDATA[Microbial responses in a cold waterlogged paddy field to different distances from a drainage ditch]]> ABSTRACT Cold waterlogged paddy field is a type of low-yield paddy soil, and opening a drainage ditch has been suggested to improve waterlogged paddy soil and to increase the rice yield. However, little has been done on the role of a drainage ditch in ameliorating waterlogged soil. In the present study, rice (Oryza sativa L.) yield, soil physicochemical properties, microbial abundances and community structures in the surface soil of a cold waterlogged paddy field, which has three treatments with different distances from a drainage ditch including 5, 15 and 25 m were investigated. The results showed that opening a drainage ditch had a significant effect on the rice yield and soil physicochemical properties. Sampling sites near the drainage ditch such as 5 m-site had higher yield and soil nutrients, however, 25 m-site had lower values. Bacterial 16S rRNA gene did not exhibit a regular pattern but fungal abundance decreased sharply with increasing distance from the drainage ditch. The most abundant bacterial phyla across all soil samples were Proteobacteria, Acidobacteria, Planctomycetes and Chloroflexi. Abundant fungal phyla were Ascomycota, Zygomycota and Basidiomycota. Three treatments had similar microbial community compositions but with different relative abundances. The Bray-Curtis distance demonstrated that microbial community structures were divided into two major groups, samples of 5 m- and 15 m-site clustered into one group and samples of 25 m-site was another group. Moreover, redundancy analysis revealed that soil redox potential and total reducing substances were significant factors in shaping microbial community structures. The abundant aerobic bacteria were observed at the 5 m- and 15 m-site, in contrast, abundant anaerobic bacteria were observed at the 25 m-site. In conclusion, opening a drainage ditch in cold waterlogged paddy fields affects rice yield, soil nutrients, microbial abundances and community structures. <![CDATA[An efficient method for in vitro propagation of <em>Alstroemeria pallida</em> Graham rhizomes]]> ABSTRACT Alstroemeria is a genus native to South America and commercially has commonly been propagated vegetatively by rhizome division, with low efficiency, high time consumption and a high risk of virus dissemination. In vitro propagation has several advantages, particularly in terms of efficiency and has been applied to the micropropagation of alstroemeria. This study aims to describe an efficient method for the in vitro propagation of Alstroemeria pallida Graham, a Chilean native species of high ornamental value. Concentrations of agar (0.0, 3.5 and 7.0 g L-1) and 6-benzylaminopurine (BAP) (0.0, 0.5, 1.0 and 2.0 mg L-1) were supplemented with MS culture medium to evaluate explant weight (g), rhizome length (cm), shoot length (cm) and proliferation rate. The highest explant weight was observed in rhizomes grown in culture medium supplemented with 3.5 gL-1 agar (3.79 g), and treatments using 2.0 g L-1 BAP showed the highest weight increase (3.33 g) after 8 wk. The proliferation rate rose with increasing concentrations of BAP, whereas low concentrations of BAP promoted longer shoots. An efficient method for in vitro propagation of A. pallida rhizomes was described, which could be useful for its conservation, domestication and further breeding.