Variation in floristic and trait composition along environmental gradients in the herb layer of temperate forests in the transition zone between Central and SE Europe

Species- and trait-environment linkages in forest plant communities continue to be a frequent topic in ecological research. We studied the dependence of floristic and functional trait composition on environmental factors, namely local soil properties, overstory characteristics, climatic parameters and other abiotic and biotic variables. The study area comprised 50 monitoring plots across Slovenia, belonging to the EU ICP Forests monitoring network. Vegetation was surveyed in accordance with harmonized protocols, and environmental variables were either measured or estimated during vegetation sampling. Significant predictors of species composition were identified by canonical correspondence analysis. Correlations between plant traits, i.e. plant growth habit, life form, flowering features and CSR signature, were examined with fourth-corner analysis and linear regressions. Our results show that variation in floristic composition was mainly explained by climatic parameters (mean annual temperature, mean annual precipitation), soil properties (pH) and tree layer-dependent light conditions. Trait composition was most closely related with tree layer characteristics, such as shade-casting ability (SCA, a proxy for light availability in the understory layer), tree species richness and tree species composition. Amongst soil properties, total nitrogen content and soil texture (proportion of clay) were most frequently correlated with different species traits or trait states. The CSR signature of herb communities was associated with tree layer SCA, soil pH and mean annual temperature. The floristic composition of the studied herb-layer vegetation depended on temperature and precipitation, which are likely to be influenced by ongoing climate change (warming and drying). Trait composition exhibited significant links to tree layer characteristics and soil conditions, which are in turn directly modified by forest management interventions.

Hotter chili peppers by hybridisation: heterosis and reciprocal effects

The selection of pure lines followed by crosses to create superior hybrids is one of the oldest strategies in crop breeding. However, in domesticated species of the Capsicum genus hybrid breeding has lagged, in part due to a lack of detailed information about the phenotypic and metabolic consequences of hybridization. Here, we performed reciprocal crosses between four inbred varieties of two species of cultivated C. chinense (cv. Habanero and Biquinho) and C. annuum var. annuum (cv. Jalapeño and cv. Cascadura Ikeda). These varieties were specifically selected for their highly divergent traits, including plant growth habit, fruit size, shape and pungency: Habanero and Jalapeño peppers are highly pungent forms, particularly popular in Mexico. The Biquinho cultivar of C. chinense and the Cascadura Ikeda bell pepper are traditional sweet cultivars from Brazil. From the parental genotypes and from the progeny of the reciprocal crosses, we measured 31 phenotypic traits, including plant growth, and yield, 32 fruit shape parameters, and 50 fruit pericarp and placenta metabolites, including capsaicinoids. We found large differences for agronomic and metabolic traits between the genotypes, including heterosis for pungency and reciprocal effects for agronomic traits. We also show that the strong association between fruit shape and pungency can be broken in intraspecific hybrids, paving the way for the precision breeding of novel varieties.

Species Identification and Morphological Trait Diversity Assessment in Ryegrass (Lolium spp.) Populations from Texas Blacklands

Ryegrass (Lolium spp.) is a troublesome weed in major wheat producing regions in the U.S. High diversity and adaptive potential are known to contribute to its success as a weed species and also create difficulties in correct species identification in fields. The objective of this research was to characterize diversity for 16 different morphological traits among 56 Lolium populations collected from wheat (Triticum aestivum L.) production fields across the Texas Blacklands region and identify specific Lolium species based on taxonomical characteristics. Populations were highly diverse (both at inter- and intra-population levels) for the traits studied, and a taxonomical comparison with USDA-GRIN reference samples revealed that all the populations were variants of Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] with a few offtypes of perennial (Lolium perenne L.) or probable hybrids between the two species. Hierarchical clustering grouped the populations into 6 clusters based on their similarities for the morphological traits investigated. Principal component analysis showed that the variability for yield traits greatly contributed to the total diversity. Pre-flowering plant height (stage 10 on Feekes scale) was positively correlated with tiller count, shoot biomass, spike count, but not with total seed count/plant, whereas plant height at maturity (stage 11.3-11.4 on Feekes scale) was highly correlated with total seeds/plant. Further, basal node color was positively correlated with plant growth habit, regrowth rate, and leaf color. Leaf blade width was positively correlated with survival to pinoxaden and multiple herbicides, whereas, spike count was negatively correlated with survival to mesosulfuron. The high levels of intra- as well as inter-population variability documented in this study indicates the potential of this species to rapidly adapt to herbicides, and emphasizes the need for implementing diverse management tactics including the integration of harvest weed seed control.

Loci discovery, network-guided approach, and genomic prediction for drought tolerance index in a multi-parent advanced generation intercross (MAGIC) cowpea population

Cowpea is a nutrient-dense legume that significantly contributes to the population’s diet in sub-Saharan Africa and other regions of the world. Improving cowpea cultivars to be more resilient to abiotic stress such as drought would be of great importance. The use of a multi-parent advanced generation intercross (MAGIC) population has been shown to be efficient in increasing the frequency of rare alleles that could be associated with important agricultural traits. In addition, drought tolerance index has been reported to be a reliable parameter for assessing crop tolerance to water-deficit conditions. Therefore, the objectives of this study were to evaluate the drought tolerance index for plant growth habit, plant maturity, flowering time, 100-seed weight, and grain yield in a MAGIC cowpea population, to conduct genome-wide association study (GWAS) and identify single nucleotide polymorphism (SNP) markers associated with the drought tolerance indices, to investigate the potential relationship existing between the significant loci associated with the drought tolerance indices, and to conduct genomic selection (GS). These analyses were performed using the existing phenotypic and genotypic data published for the MAGIC population which consisted of 305 F8 recombinant inbred lines (RILs) developed at University of California, Riverside. The results indicated that: (1) large variation in drought tolerance indices existed among the cowpea genotypes, (2) a total of 14, 18, 5, 5, and 35 SNPs were associated with plant growth habit change due to drought stress, and drought tolerance indices for maturity, flowering time, 100-seed weight, and grain yield, respectively, (3) the network-guided approach revealed clear interactions between the loci associated with the drought tolerance traits, and (4) the GS accuracy varied from low to moderate. These results could be applied to improve drought tolerance in cowpea through marker-assisted selection (MAS) and genomic selection (GS). To the best of our knowledge, this is the first report on marker loci associated with drought tolerance indices in cowpea.

Phenotypic variability of cowpea genotypes for immature seed harvesting

ABSTRACT Seed color, brightness and texture are important aspects for the consumption of immature beans. This study aimed to estimate the phenotypic variability among thirty cowpea genotypes for immature seed harvesting, in order to guide breeding programs. The experiment was carried out in a randomized blocks design, with three replications. The evaluated traits were immature seeds yield, pods and dry seeds production, number of immature pods, 100-immature seeds weight, immature pods length, number of seeds per immature pod, cooking time, harvesting period of immature pods, seed color, pod color, plant growth habit, opening of immature pods, seed threshing from immature pods, cultivation value and seed browning after threshing. Anova and three clustering methods were applied: UPGMA using the Jaccard coefficient of similarity; modified Tocher method based on the Gower algorithm; and k-means. All the analyses were performed based on the variable means of experiments evaluated in six environments. A statistically significant phenotypic variability was observed among all the quantitative traits. Discrepancies occurred in the accessions grouping and number of clusters. The accession BRS Acauã, in one group, and P508 and PCCR3F6L15, in other groups, showed a good quality for immature grain harvesting, were consistently grouped into different clusters and are recommended for use as parents in the development of new cultivars.

Agro-Morphological Characterization of Sicilian Chili Pepper Accessions for Ornamental Purposes

The species belonging to the genus Capsicum have been widely used as decorative vegetables, however only a few genotypes are available for this purpose. The goal of the present work was the agro-morphological characterization of several chili pepper accessions cultivated into different pot sizes (10, 14, 18 or 20 cm diameters). The agro-morphological characterization of 19 accessions was performed following IPGR (International Plant Genetic Resources Institute) descriptors: plant height (PH), plant canopy width (PCW), PH/PCW ratio, plant growth habit, plant visual quality, first flower emission, fruiting start, end of harvest, fruit number, fruit length, fruit width, fruit color at mature stage and fruit shape. Analysis of Variance (ANOVA) for all observed traits showed statistical significant differences among the genotypes tested. Results of the heat map complementarily secured the frequency of multiplicity highlighted from the ANOVA analysis. Furthermore, the present study pointed out that A33, A27, G1 and A1 chili pepper accessions achieved optimal performances in terms of plant visual quality, which is a crucial trait for ornamental purposes.

Physiological quality of conventional soybean cultivars of seeds as a function of pod position in plant canopy

Soybean cultivars have different growth habits, and the cultivation of those of indeterminate habit has increased significantly in Brazil. Thus, the aim of this study was to evaluate the physiological quality of soybean seeds produced in two harvests, from cultivars with different growth habits and ripening cycles, harvested in different canopy thirds of the plant in the canopy. The seeds were produced in Ipameri, Goiás –Brazil, in two crop harvests, 2014/15 and 2015/16. A completely randomized design was used in a 4x3 factorial scheme with four replications. The treatments consisted of four soybean cultivars with different growth habits and ripening cycles (BRS 6780, BRS 6980, BRS 7980 and BRS 8381), harvested in three positions of the plant canopy (upper, middle and lower). Germination, first count, accelerated aging and electrical conductivity tests were performed. It was observed that the physiological quality of genetic materials studied was influenced by the variable environmental conditions. Soybean cultivars the early cycles produced seeds of superior physiological quality, regardless of plant growth habit. Seeds of soybean cultivars of indeterminate and determined growth habits and earlier cycle, harvested from the upper and middle thirds of the plant, are of better quality. Finally, cultivars with semi-determined and determined habits and late cycles will produce lower quality batches of seeds, regardless of which third of the plant they were harvested.

Development and Characterization of an Ethyl Methane Sulfonate (EMS) Induced Mutant Population in Capsicum annuum L.

Plant breeding explores genetic diversity in useful traits to develop new, high-yielding, and improved cultivars. Ethyl methane sulfonate (EMS) is a chemical widely used to induce mutations at loci that regulate economically essential traits. Additionally, it can knock out genes, facilitating efforts to elucidate gene functions through the analysis of mutant phenotypes. Here, we developed a mutant population using the small and pungent ornamental Capsicum annuum pepper “Micro-Pep”. This accession is particularly suitable for mutation studies and molecular research due to its compact growth habit and small size. We treated 9500 seeds with 1.3% EMS and harvested 3996 M2 lines. We then selected 1300 (32.5%) independent M2 families and evaluated their phenotypes over four years. The mutants displayed phenotypic variations in plant growth, habit, leaf color and shape, and flower and fruit morphology. An experiment to optimize Targeting Induced Local Lesions IN Genomes (TILLING) in pepper detected nine EMS-induced mutations in the eIF4E gene. The M2 families developed here exhibited broad phenotypic variation and should be valuable genetic resources for functional gene analysis in pepper molecular breeding programs using reverse genetics tools, including TILLING.

Screening of chilli pepper genotypes against anthracnose (Colletotrichum brevisporum)

Anthracnose is the most important disease of chili pepper pimenta-de-cheiro (Capsicum chinense Jacq.). This species is widely cultivated in dryland areas in the Amazon, presenting high genetic diversity. Therefore, it presents a high potential for use in breeding. The objective of this study was to select pepper genotypes with potential resistance to anthracnose (Colletotrichum brevisporum). For this purpose, ripe fruits of pepper were acquired from the producing farms in the municipalities of Iranduba, Manacapuru, Rio Preto da Eva and Presidente Figueiredo. The experiments were conducted in seedlings (Phase I) and in mature and immature fruits (Phase II). The evaluation of the disease severity was performed using a scale of scores. The morphoagronomic characterization of the genotypes considered the fruits in the immature and mature stages and plant growth habit. The injured areas in the immature fruits ranged from 0.3 to 9.7 cm2 and in the mature areas, it ranged from 0.2 to 9.9 cm2. The genotypes RPE41 and MPU29 indicated resistance to anthracnose in both stages. The morphoagronomic characterization of the fruits revealed variability for mass (5.58 to 13.74 g), length [C] (4.08 to 8.16 cm), diameter [D] (1.74 to 2.54 cm), L/D ratio (1.88 to 4.70) and color of the fruit.