Genetic association analysis in sugarcane (Saccharum spp.) for sucrose accumulation in humid environments in Colombia.

BACKGROUND: Sucrose accumulation in sugarcane is affected by several environmental and genetic factors, with plant moisture being of critical importance for its role in the synthesis and transport of sugars within the cane stalks, affecting the sucrose concentration. In general, rainfall and high soil humidity during the ripening stage promote plant growth, increasing the fresh weight and decreasing the sucrose yield in the humid region of Colombia. Therefore, this study aimed to identify markers associated with sucrose accumulation or production in the humid environment of Colombia through a genome-wide association study (GWAS). RESULTS: Sucrose concentration measurements were taken in 220 genotypes from the Cenicaña's diverse panel at 10 (early maturity) and 13 (normal maturity) months after planting. For early maturity data was collected during plant cane and first ratoon, while at normal maturity it was during plant cane, first, and second ratoon. A total of 137,890 SNPs were selected after sequencing the 220 genotypes through GBS, RADSeq, and whole-genome sequencing. After GWAS analysis, a total of 77 markers were significantly associated with sucrose concentration at both ages, but only 39 were close to candidate genes previously reported for sucrose accumulation and/or production. Among the candidate genes, 18 were highlighted because they were involved in sucrose hydrolysis (SUS6, CIN3, CINV1, CINV2), sugar transport (i.e., MST1, MST2, PLT5, SUT4, ERD6 like), phosphorylation processes (TPS genes), glycolysis (PFP-ALPHA, HXK3, PHI1), and transcription factors (ERF12, ERF112). Similarly, 64 genes were associated with glycosyltransferases, glycosidases, and hormones. CONCLUSIONS: These results provide new insights into the molecular mechanisms involved in sucrose accumulation in sugarcane and contribute with important genomic resources for future research in the humid environments of Colombia. Similarly, the markers identified will be validated for their potential application within Cenicaña's breeding program to assist the development of breeding populations.

Effects of hot and humid environments on thermoregulation and aerobic endurance capacity of Laser sailors.

Objectives: The purpose was to investigate the effects of hot and humid environments on thermoregulation and aerobic endurance capacity and whether high skin temperature serves as a more important thermoregulatory factor affecting aerobic exercise capacity. Methods: A randomized cross-over design was applied to this study, in which nine Laser sailors performed the 6 km rowing test (6 km test) in both a warm (ambient temperature: 23 ± 1.4 °C; relative humidity: 60.5 ± 0.7%; wind speed: 0 km/h; WARM) and hot environment (ambient temperature: 31.8 ± 1.1 °C; relative humidity: 63.5 ± 4.9%; wind speed: 3.5 ± 0.7 km/h; HOT). Results: The time for completing 6 km test of HOT group was significantly longer than that of WARM group (P = 0.0014). Mean power of 3-4 km, 4-5 km and 5-6 km were significant lower in HOT group (P = 0.014, P = 0.02, P = 0.003). Gastrointestinal temperature and skin temperature were significantly higher in HOT group during the 6 km test (P = 0.016, P = 0.04). Heat storage at 5 min and 15 min of HOT group were significantly higher than that of WARM group (P = 0.0036; P = 0.0018). Heart rate and physiological strain index of HOT group were significantly higher than that of WARM group during the 6 km test (P = 0.01, P < 0.01). Conclusion: When skin temperature and core temperature both increased, high skin temperature may be the more important thermoregulatory factor that affected the aerobic endurance performance in hot and humid environments. The high skin temperature narrowed the core to skin temperature gradient and skin to ambient temperature gradient, which may result in greater accumulation of heat storage. The greater heat storage led to the lower muscle power output, which contributed to the reduction of the heat production.

Anthropogenic and climatic influences in the swamp environment of the Pandeiros River basin, Minas Gerais-Brazil.

Several environmental impacts are resulting from the process of anthropization and climate variability that have caused degradation of biomes and humid environments. Thus, the objective of this study was to evaluate the effect of the anthropic process and the variation of climatic conditions on the dynamics of the marsh vegetation in the Pandeiros River preservation area in the north of Minas Gerais, Brazil. The Enhanced Vegetation Index (EVI) of product MOD13Q1 and the gross primary productivity (GPP) of product MOD17A2 of the Moderate Resolution Imaging Spectroradiometer (MODIS) were used for the period from 2001 to 2017 were used in this process. Rain and air temperature data were obtained from the Conventional Weather Station of Januária-MG. The time series were submitted to the nonparametric statistical test of Mann-Kendall. The process of anthropization of the swamp area in the environmental protection area of the Pandeiros River/MG (EPA) showed a pattern of expansion of vegetation cover associated with the reduction of the water table, a phenomenon resulting from the silting process and reduction of the incidence of rain in this region, which contributes to the reduction of ecosystem services. Thus, understanding the influence of climatic variables on the dynamics of vegetation in humid environments, such as the EPA swamp area on the Pandeiros River, is essential for the preservation and recovery of these ecosystems and for the implementation of public policies for preservation and conservation.

Mitigating the effects of drought on cattle production in communal rangelands of Zimbabwe.

The objective of the study was to examine strategies employed by farmers to mitigate the effects of drought on cattle production in communal rangelands of Zimbabwe. Data were collected from a total of 316 communal cattle farming households selected from semi-arid and sub-humid environments (158 each) using structured questionnaires. Farmers in sub-humid environments mostly resorted to controlled migration in search of pastures during drought whilst those in semi-arid environments mainly supplemented their cattle (P < 0.05). Travelling long distances to centralized water tanks was ranked first as a strategy to counter water shortage in sub-humid environments whilst in semi-arid environments farmers mostly resorted to use of boreholes (P < 0.05). Farmers in sub-humid environments were more than twice more likely to supplement their cattle than those in semi-arid environments (P < 0.05). Crop residues were the main type of feed used to supplement cattle during drought periods (P > 0.05). Mashona cattle were the most preferred breed (P > 0.05). Conformation traits were less preferred in both environments (P < 0.05). It was concluded that communal cattle producers in both environments use dietary supplementation with crop residues and controlled migration in search of pastures and water to mitigate drought effects. Given the shortcomings associated with drought mitigation strategies being used by communal cattle farmers, current findings suggest the need to design and implement sustainable strategies such as breeding cattle for drought resilience and selective supplementary feeding.

Effects of drought on cattle production in sub-tropical environments.

The objective of the study was to assess farmer perceptions on effects of drought on cattle production in sub-tropical environments. Data was collected from a total of 314 cattle-owning households from semi-arid and sub-humid environments using pre-tested structured questionnaires. Drought was highly ranked common cause of cattle loss in semi-arid (ranked third) whilst in sub-humid conditions it was lowly ranked (ranked sixth; P < 0.05). Water shortage was ranked as the constituent of drought with the most severe impact on cattle production in semi-arid environments whilst in sub-humid environments feed shortage was ranked first (P < 0.05). Mortalities were ranked as the most common effect of drought in semi-arid environments whilst in sub-humid environments parasite incidence was ranked first (P < 0.01). Lactating and pregnant cows in sub-humid environments were more likely to be emaciated during droughts periods than those in semi-arid environments (P Ë‚ 0.05). Starvation, a stressor which is directly related to drought, was the major cause of cattle losses in sub-humid environments. Diseases and parasites, which can be exacerbated by drought, were the major cause of cattle losses in semi-arid environments. Cows and calves are more vulnerable to emaciation during drought periods in sub-humid environments than in semi-arid environments.

The evolution of bipedalism in jerboas (rodentia: Dipodoidea): origin in humid and forested environments.

Mammalian bipedalism has long been thought to have arisen in response to arid and open environments. Here, we tested whether bipedalism coevolved with environmental changes using molecular and paleontological data from the rodent superfamily Dipodoidea and statistical methods for reconstructing ancestral characteristics and past climates. Our results show that the post-Late Miocene aridification exerted selective pressures on tooth shape, but not on leg length of bipedal jerboas. Cheek tooth crown height has increased since the Late Miocene, but the hind limb/head-body length ratios remained stable and high despite the environmental change from humid and forested to arid and open conditions, rather than increasing from low to high as predicted by the arid-bipedalism hypothesis. The decoupling of locomotor and dental character evolution indicates that bipedalism evolved under selective pressure different from that of dental hypsodonty in jerboas. We reconstructed the habitats of early jerboas using floral and faunal data, and the results show that the environments in which bipedalism evolved were forested. Our results suggest that bipedalism evolved as an adaptation to humid woodlands or forests for vertical jumping. Running at high speeds is likely a by-product of selection for jumping, which became advantageous in open environments later on.