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Buenos Aires, Argentina

The National University of Lomas de Zamora is an Argentine state national university located in Lomas de Zamora, Buenos Aires Province. Maintaining extensive research facilities, and with over 30,000 students, UNLZ is one of the most important universities of the Greater Buenos Aires area.The university includes five departments: Agronomy, Economics, Engineering, Law, and Social science. The Media Department, part of the School of Social science, publishes InfoRegión, an online periodical covering the Greater Buenos Aires area. Wikipedia.

Alvarez Prado S.,National University of Rosario | Lopez C.G.,National University of Lomas de Zamora | Gambin B.L.,National University of Rosario | Abertondo V.J.,NIDERA S.A | Borras L.,National University of Rosario
Field Crops Research

Knowledge on the genetic bases of physiological processes determining maize kernel weight (KW) is relevant for maize yield improvement. However, little is known about the genetic control of KW and its component traits: kernel growth rate (KGR) and grain-filling duration (GFD). We phenotyped several grain-filling traits in 245 RILs from the IBM Syn4 population (B73×Mo17) under two environments, and a multi-trait multi-environment quantitative trait loci (QTL) analysis was conducted. We were specifically interested in seeking genetic links of known correlated traits at the phenotypic level, like kernel maximum water content (MWC) and KGR. Our specific objectives were (i) to conduct a QTL analysis over grain-filling traits to determine their genetic complexity, (ii) to study the relationships between kernel developmental traits at phenotypic and genetic levels, and (iii) to suggest possible candidate genes for each specific trait using detected QTL and B73 sequence data.All traits showed significant genotype × environment interactions (p< 0.001) and large phenotypic variability. KW variability was positively associated (p< 0.01) with variations in KGR (r= 0.79) and GFD (r= 0.32). As expected, KGR was positively correlated to MWC, while GFD was negatively correlated to the kernel moisture concentration at physiological maturity (MCPM). A total of 10 joint QTL were detected under both environments, located on chromosomes 1, 2, 4, 5, 6, 7, 9 and 10. Most QTL showed inconsistent effects underlying genotype × environment interactions. However, the multi-trait multi-environment approach helped understand genetic correlations between traits, where positive and consistent genetic correlations were observed between KW, KGR and MWC on chromosomes 2, 6, 9 and 10. Only one consistent QTL for KW, GFD and kernel desiccation rate (KDR) was detected. KGR and GFD showed no common consistent QTL, supporting previous observations on independent physiological control. Several detected QTL co-localized with previous mapping studies. With the use of B73 sequence data we described genes within QTL marker intervals, and discussed relevant candidate ones for future dissection. Results showing the co-localization of consistent QTL for KW, KGR and MWC suggest a common genetic basis for these critical secondary traits measured under field conditions. © 2013 Elsevier B.V. Source

Laserna M.P.,University of Buenos Aires | Maddonni G.A.,University of Buenos Aires | Lopez C.G.,National University of Lomas de Zamora
Field Crops Research

The use of transgenic maize (Zea mays L.) hybrids (Bt, RR, Bt-RR) has simplified crop husbandry, mainly due to a more effective control of pests and weeds. The effects of transgenes insertion on phenotypic traits of maize hybrids are not fully documented, especially without the incidence of pests and weeds. The objectives of this work were (i) to establish phenotypic differences in terms of phenology, growth and yield among a non-transgenic maize hybrid and their transgenic versions (Bt hybrid, RR hybrid and Bt-RR hybrid) and among the transgenic versions of other genetic background and (ii) to analyze the impact of crowding stress on inter-plant variability of the different traits under study. Field experiments were conducted in Buenos Aires (34°36'S, 58°26'W), Argentina during 2008-2009 (Exp 1), 2009-2010 (Exp 2) and 2010-2011 (Exp 3). Genotypes were cultivated at contrasting plant densities (6 and 12plm -2 in Exp 1 and Exp 2) and with contrasting inter-plant spaces within the row (Exp 3), irrigated, without nutrient limitations, and with chemical and mechanical controls of weed and animal pests. At both plant densities, phenotypic variability of several traits among versions within each group was recorded. For example, the RR version of DK747 group had the shortest thermal time to flowering. The stacked transgenic hybrids DK747MGRR and DK190MGRR, exhibited the highest ear growth rate (EGR CP) during the critical period for kernel set. However, both genotypes had the lowest reproductive efficiency (i.e. kernel number per unit of EGR CP), that counterbalanced their higher EGR CP. Only the Bt-RR version of DK747 showed a higher inter-plant variability (CV) of EGR CP at low mean EGR CP values a symptom of the intolerance of this genotype to crowing stress. Consequently, the different versions of each group of hybrids had a similar kernel number per plant and grain yield. We conclude that the introduction of transgenes may alter in some way, the behavior of plants in different eco-physiological aspects in the absence of pests and weeds. © 2012 Elsevier B.V. Source

Lovisolo M.R.,National University of Lomas de Zamora | Galati B.G.,University of Buenos Aires
Boletin de la Sociedad Argentina de Botanica

Anthers of ten species of Poaceae from the province of Buenos Aires (Argentina) were investigated with scanning and transmission electron microscopes. The orbicules can be defined as corpuscles of variable size that show the same electron-density, reaction to the dyes, autofluorescence and resistance to acetolysis as pollen exine does. The orbicules are randomly dispersed on the inner anther locule and they are often attached to a tapetal membrane. In this study, four different types and four subtypes of orbicules were identified. We conclude that the different orbicules types described in this work are representative of the studied tribes, and we suggest that the orbicules morphology may be a useful character in systematic studies. Source

Huarte H.R.,Argentine Catholic University | Huarte H.R.,National University of Lomas de Zamora | Benech-Arnold R.L.,University of Buenos Aires
Seed Science Research

Cynara cardunculus (L.) seeds require incubation at fluctuating temperatures to terminate dormancy. In this study, we analysed the physiological mechanisms underlying such a requirement, focusing on the role of abscisic acid (ABA) and gibberellin (GA). As a conceptual framework, we considered the possibility that fluctuating temperatures and light trigger a similar set of hormonal processes after stimulus perception. To test this possibility, we (1) carried out hydrotime analysis of germination in seeds exposed to fluctuating temperatures (25/15°C) and constant temperature (20°C) with or without gibberellin (GA3) or red light; (2) determined the responses of seeds incubated at fluctuating or constant temperature to ABA, GA3, fluridone, an inhibitor of ABA biosynthesis, and paclobutrazol, an inhibitor of GA biosynthesis; and (3) determined the ABA content of seeds incubated at fluctuating or constant temperature. Incubation at 25/15°C or 20°C in the presence of GA3 reduced the mean base water potential [b(50)] of the population to a similar extent, compared to that observed with seeds incubated at 20°C without GA3. Irradiation with red light also reduced b(50) to a lesser extent than incubation in the presence of GA3. At all concentrations tested, exogenously applied GA3 did not promote germination of seeds incubated at 25/15°C. However, paclobutrazol inhibited germination, suggesting that fluctuating temperatures terminate dormancy through de novo GA biosynthesis. Fluctuating temperatures enhanced seed germination in the presence of ABA, but ABA content did not differ between seeds incubated at fluctuating and constant temperatures. This study provides clear evidence for the involvement of hormonal regulation in dormancy termination by fluctuating temperatures. Copyright © Cambridge University Press 2010. Source

Blanco M.R.,National University of Lomas de Zamora | Alonso C.R.,National University of La Plata
Journal of Muscle Foods

Composition and amount of intramuscular connective tissue vary among muscles, age and breed. The purpose of this study was to determine in vivo the proportion of collagen I and III fibers in the Longissimus thoracis (LT) and Gluteus medius (GM) muscles at different ages (6, 12 and 24 months) in the Criolla and Aberdeen Angus bovine breed (24 months) Muscular samples were taken and histological cuts were treated with the picrosirius-red polarization method. The study was performed by light microscope with Polaroid filters and ocular reticulum. Type I fibers between GM and LT muscles, has shown differences only at 12 months old. Regarding Type III fibers, no differences were found between the both muscles at the three ages. When GM muscle was studied, differences were observed in the Type I fibers among the three ages, the major percentage was observed at 24 months. Significant differences were found in Type I as well as Type III fibers in LT at 24 months between Aberdeen Angus and Criolla breeds. Journal compilation. © 2010, Wiley Periodicals, Inc. Source

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