Implications of the clone by harvest interaction in the selection of sugarcane genotypes in a regionalized program.

The recommendation of sugarcane clones depends on several factors, as the response or performance of the clones over different cuts or harvests. The clone by harvest interaction might be difficult to identify superior clones in the final stages of the sugarcane breeding program. Thus, the objective of this study was to investigate and describe the implications of the genotype by harvest interaction in the adaptability and stability of genotypes and delineation of mega-environments from a set of multi-environment trials. Fifteen clones and four checks were evaluated in eight environments. The trait TPH (tons of pol per hectare) was evaluated in two harvests (plant cane and ratoon cane) in 2010 and 2011. The joint analysis showed significance for harvest (H), environment (E), and genotype (G) effects. The interactions GxE, ExH, GxH, and ExGxH were also significant. The last three-way interaction indicated the differential response of the genotypes over environments, and that it depends on the harvests. The overall mean of the trials was 12.77 TPH. The coefficient of variation was 8.70% and the selective accuracy was 98.63%, indicating high experimental precision. The genotypes G4, G14, and G16 were statistically superior to the check varieties used; however, these genotypes did not show high stability as described by the additive main effects and multiplicative interaction method. There was a specific adaptation between the E7 and E5 environments and the G4 and G5 genotypes, respectively. In general, the grouping of the environments was inconsistent throughout the harvests, except for the E1 and E4 environments, which exhibited similarities for the different genotypes.

Multivariate statistics applied to the reaction of common bean plants to parasitism by Meloidogyne javanica.

The availability of common bean cultivars tolerant to Meloidogyne javanica is limited in Brazil. Thus, the present study aimed to evaluate the reactions of 33 common bean genotypes (23 landrace, 8 commercial, 1 susceptible standard and 1 resistant standard) to M. javanica, employing multivariate statistics to discriminate the reaction of the genotypes. The experiment was conducted in a greenhouse using a completely randomized design with seven replicates. The seeds were sown in 1-L pots containing autoclaved soil and sand in a 1:1 ratio (v:v). On day 19, after emergence of the seedlings, the plants were treated with inoculum containing 4000 eggs + second-stage juveniles (J2). At 60 days after inoculation, the seedlings were evaluated based on biometric and parasitism-related traits, such as number of galls, final nematode population per root system, reproduction factor, and percent reduction in the reproduction factor of the nematode (%RRF). The data were subjected to analysis of variance using the F-test. The Mahalanobis generalized distance was used to obtain the dissimilarity matrix, and the average linkage between groups was used for clustering. The use of multivariate statistics allowed groups to be separated according to the resistance levels of genotypes, as observed in the %RRF. The landrace genotypes FORT-09, FORT-17, FORT-31, FORT-32, FORT-34 and FORT-36 presented resistance to M. javanica; thus, these genotypes can be considered potential sources of resistance.

Dissimilarity between Mouriri elliptica (Mart.) plants cultivated in vitro and in situ through anatomic parameters.

Mouriri elliptica (Mart.) is a genetic resource of the Cerrado domain, which has potential for food and medicinal use. A few studies have been performed on its in vitro propagation, and no studies have examined dissimilarities between plants of this species when cultivated in situ or in vitro. Therefore, the objective of the present study was to identify in vitro cultivation conditions that permit the formation of plantlets with leaf anatomical features that are less dissimilar to those of plants grown in situ. Thus, an anatomical study of the leaves was conducted to investigate the adaxial epidermis thickness, abaxial epidermis thickness, chlorenchyma thickness, stomatal crypt depth, stomatal crypt density, and leaf surface stomatal crypt aperture area. The distance between phenotypes was determined based on micromorphometric data, and unweighted pair group mean arithmetic clustering was performed. Four different groups were tested, and cultivation with sucrose and 50 and 75 µmol⋅m-2⋅s-1 irradiance was found to promote plantlet development and maximize similarity to plants cultivated in situ. The most important anatomical parameters in this study were the stomatal crypt aperture area and the crypt density. This study is of importance for the anatomical characterization of M. elliptica (Mart.) leaves, as it identifies plasticity as a function of in vitro culture conditions.

TRPV4 mediates flow-induced increases in intracellular Ca in medullary thick ascending limbs.

UNLABELLED: Medullary thick ascending limbs (mTAL) regulate Na balance and therefore blood pressure. We previously showed that cell swelling and luminal flow activates the mechanosensitive channel TRPV4 in mTAL. AIM: We hypothesized that TRPV4 mediates flow-induced increases in intracellular Ca (Cai) in rat mTALs. METHODS: We performed ratiometric measurements of Cai in perfused mTALs. RESULTS: Increasing luminal flow from 0 to 20 nL min(-1) caused Cai to peak 231 ± 29 nmol L(-1) above basal concentrations (n = 18). The general TRPV inhibitor ruthenium red at 15 and 50 µmol L(-1) reduced peak Cai by 41 ± 9 (P < 0.01; n = 5) and 77 ± 10% (P < 0.02; n = 6). The selective TRPV4 inhibitor RN1734 at 10 and 50 µmol L(-1) reduced peak Cai by 46 ± 11 (P < 0.01; n = 7) and 76 ± 5% (P < 0.02; n = 5) respectively. To specifically target TRPV4, mTALs were transduced with adenoviruses expressing TRPV4 small hairpin (sh) RNA. In non-transduced control mTALs, luminal flow generated a peak increase in Cai of 111 ± 21 nmol L(-1) (n = 8). In TRPV4shRNA-transduced mTALs, the Cai peak was reduced to 56 ± 8 nmol L(-1) (P < 0.03, n = 9). Removing extracellular Ca completely abolished flow-induced increases in Cai. Increasing luminal flow in the presence of hexokinase 20 (U mL(-1) ) to scavenge extracellular ATP did not modify significantly the increases in Cai induced by luminal flow. Finally, we studied the effect of the TRPV4 selective agonist GSK1016790A on Cai. In the absence of luminal flow, GSK1016790A (10 nmol L(-1) ) increased Cai from 60 ± 11 nmol L(-1) to 262 ± 71 nmol L(-1) (P < 0.05; n = 7). CONCLUSION: We conclude that flow-induced increases in Cai are mediated primarily by TRPV4 in the rat mTAL.

Molecular characterization of Anthurium genotypes by using DNA fingerprinting and SPAR markers.

We characterized single primer amplification reaction (SPAR) molecular markers from 20 genotypes of Anthurium andraeanum Lind., including 3 from commercial varieties and 17 from 2 communities in the State of Espírito Santo, Brazil. Twenty-four SPAR, consisting of 7 random amplified polymorphic DNA and 17 inter-simple sequence repeat markers were used to estimate the genetic diversity of 20 Anthurium accessions. The set of SPAR markers generated 288 bands and showed an average polymorphism percentage of 93.39%, ranging from 71.43 to 100%. The polymorphism information content (PIC) of the random amplified polymorphic DNA primers averaged 0.364 and ranged from 0.258 to 0.490. Primer OPF 06 showed the lowest PIC, while OPAM 14 was the highest. The average PIC of the inter-simple sequence repeat primers was 0.299, with values ranging from 0.196 to 0.401. Primer UBC 845 had the lowest PIC (0.196), while primer UCB 810 had the highest (0.401). By using the complement of Jaccard's similarity index and unweighted pair group method with arithmetic mean clustering, 5 clusters were formed with a cophenetic correlation coefficient of 0.8093, indicating an acceptable clustering consistency. However, no genotype clustering patterns agreed with the morphological data. The Anthurium genotypes investigated in this study are a germplasm source for conservational research and may be used in improvement programs for this species.

Genetic gains in the UENF-14 popcorn population with recurrent selection.

The popcorn breeding program of Universidade Estadual do Norte Fluminense Darcy Ribeiro aims to provide farmers a cultivar with desirable agronomic traits, particularly with respect to grain yield (GY) and popping expansion (PE). We evaluated full-sib families from the seventh cycle of recurrent selection and estimated the genetic progress with respect to GY and PE. Eight traits were evaluated in 200 full-sib families that were randomized into blocks with two replicates per set in two contrasting environments, Campos dos Goytacazes and Itaocara, located in north and northwest Rio de Janeiro State, respectively. There were significant differences between sets in families with respect to all traits evaluated, which indicates genetic variability that may be explored in future cycles. Using random economic weights in the selection of superior progenies, the Mulamba and Mock index showed gains for PE and GY of 5.11 and 7.78%, respectively. Significant PE and GY increases were found when comparing the evolution of mean values of these two parameters that were assessed at cycles C0-C6 and predicted for C7. Thus, an advanced-cycle popcorn cultivar with genotypic superiority for the main traits of economic interest can be made available to farmers in Rio de Janeiro State.

Genetic diversity in local and commercial dry bean (Phaseolus vulgaris) accessions based on microsatellite markers.

Dry beans are considered to be a crop of great socio-economic importance, because they are an inexpensive source of nutrients and because their cultivation requires considerable manual labor. Studies of genetic diversity have been very important for genetic improvement programs, because they give parameters for the identification of genitors that can provide large heterosis effects and improved segregation in recombinants, increasing the probability of obtaining superior genotypes in the progeny. We evaluated the genetic diversity of 57 dry bean accessions, including 31 local accessions, propagated by small-scale farmers, 20 accessions supplied by the Brazilian Agricultural Research Agency, and six commercial accessions, using 16 microsatellite primers. Among these primers, 13 were found to be polymorphic, giving 29 polymorphic alleles. The largest number of alleles per locus was observed for primer BM141, which had four alleles. The polymorphic information content varied from 0.11 to 0.51, observed for loci BM212 and BM141, respectively. The lowest degree of dissimilarity (0.0) was found between the accession Iapar 81 and the accessions E03, E04, E09, and E13 and between the accession pairs E08 with E16 and Iapar 31 with E06. The highest degree of dissimilarity was found between the accessions Carioca and E22 (1.0). Grouping analysis revealed four groups, according to the place of origin. This tendency was also found in the principal coordinate analysis. The local genotypes were found to have relatively high genetic diversity, while the EMBRAPA and commercial cultivars had a relatively narrow genetic basis.