Influence of watertable depths on the variation of grapevine water status at the landscape scale

Determining the factors of variation of plant water status at the landscape scale is crucial for mapping or evaluating crop water requirements, crop suitability or climate change impacts over large areas. This paper studies the influence of the spatial variation of watertable fluctuations on vine water status at the scale of a 62 km² catchment, the Peyne catchment, located in the south of France. Watertable levels and vine water status were monitored over a set of 33 sites, sampling the main soil and landscape units of the study area. An integrated indicator of vineyard water status during the vegetative season, the carbon isotopic discrimination ratio in grapes, was used to estimate the spatial variation of vine water status. On a subset of nine sites, it was compared to the observed minimum predawn leaf water potential over the vegetative season, which confirmed its relevance as an indicator. Variance analysis showed that the spatial variation of watertable levels explained 28% of the variation of the observed values of the carbon isotopic discrimination ratio. It also showed that the explained variance amounted to 40% when the initial soil water storage prior to the vegetative season was taken as an additional predictor. These results point out the need to take into account the variation of local hydrological conditions as imposed by watertables levels when studying the spatial variation of plant water status or soil water balance at the landscape level.     

Molecular markers and protein quantities as genetic descriptors in maize. II. Prediction of performance of hybrids for forage traits

As it is related to the variability in genome expression, variability in protein quantities revealed by two-dimensional electrophoresis was proposed for describing phenotypic diversity. The objective of this study was to compare the predictive power of different genetic distances derived from molecular markers and from protein quantitative variations in a diallel of 210 hybrids among 21 maize inbred lines (Zea mays L.) of various origin. The lines were characterized for: 1. 142 markers resulting from the analysis of enzyme, RFLP, and protein-structure polymorphism; and 2. The variation in relative quantities of 190 proteins. The hybrids were evaluated for six forage traits in four environments. Correlations between the genetic distances computed for 142 marker loci and hybrid performances were moderate to high in diallels using crosses between related lines. Genetic distances based on protein quantities showed, in most cases, similar or lower correlations. Distance measures were not useful as predictors of hybrid performance for crosses between unrelated lines. Protein quantities were better for revealing specific genotypes.     

Isozyme diversity within African Manihot germplasm

Summary Isozyme diversity is described among a collection of 365 Manihot esculenta cultivars plus 109 accessions from wild relatives (M. glaziovii and spontaneous hybrids) from Africa. The study is based on 17 polymorphic loci. A natural hybrid swarm is detected between the two species. Although they were recently introduced, M. esculenta and M. glaziovii show high levels of polymorphism: heterozygosity estimates are 0.225 and 0.252 respectively. For the wild species, diversity is structured at the unilocus level, and the multilocus approach reveals a geographical pattern. The organization of the diversity is not so clear for the cultivated cassava, but a multilocus approach, based on both common and rare alleles, led us to identify different groups of clones with many intermediate genotypes between them. Elements of the secondary diversification process of Manihot in Ivory Coast are discussed.     

First steps towards a rational use of African rice, Oryza glaberrima, in rice breeding through a ‘contig line’ concept

The inheritance of resistance to clubroot, caused by Plasmodiophora brassicae, in Brassica oleracea was studied in the F₁, F₂and backcross progenies of four crosses between resistant and susceptible doubled haploid lines. The disease severity was scored visually on a 0–3 scale of symptom grades. These were analyzed qualitatively and quantitatively. The qualitative analysis involved the conversion of symptom grades to a classification as resistant or susceptible, and segregation ratios were used to test several simple genetic models. The quantitative analysis was based on a threshold model, in which symptom grades are considered to arise from splitting a continuous response range into disjoint intervals. This analysis was based on the maximum likelihood method, and several genetic models were evaluated.Of the four resistances studied, one was shown to be largely determined by two complementary genes. Two other resistances were also shown to be probably controlled by two genes, but the mode of inheritance was not determined unambiguously. The fourth resistance appeared to be determined by more than two genes.     

Nondestructive assessment of protein content in single seeds of rapeseed (Brassica napus L.) by near-infrared reflectance spectroscopy

The potential of near-infrared reflectance spectroscopy (NIRS) to detectwithin-plant differences for seed protein content was investigated. Fourhundred and fifty-one single seeds were scanned by NIRS using a specialadapter. After non-destructive NIRS scanning, the seeds were analysed forprotein content by the Dumas combustion method and a calibrationequation was developed. A validation set of 117 additional seeds fromthree individual plants from the cultivars Bristol, Lirajet and Maplus wasanalysed for protein content both by NIRS and combustion. The coefficientof determination between NIRS and combustion values in the validation setwas 0.94, with a standard error of performance (SEP) of 0.77% and aratio of the SEP to the standard deviation (SD) of the validation set of0.28. The coefficient of variation (CV) for seed protein content inindividual plants, as determined by the combustion method, was 11.7%for Bristol, 8.9% for Lirajet, and 9.5% for Maplus. The comparison ofsuch variation with the standard error (SE) of NIRS analysis, defined as thecombination of the SE of the combustion method and the SEP of NIRScalibration equation, revealed that the maximum explainable variance withinindividual plants that can be detected using NIRS analysis of proteincontent in single seeds was 0.86 for Bristol, 0.83 for Lirajet, and 0.85 forMaplus. These results demonstrated that NIRS is a powerful tool fornon-destructive assessment of within-plant variation for seed protein contentin rapeseed.     

Growth-related micromorphological characteristics of the porcine common carotid artery

The purpose of this study was to gain knowledge about the micromorphology of the porcine common carotid artery (CCA) during the period of growth over the bodyweight range of 10–40 kg. CCA samples from German landrace pigs (DL) aged either 2 or 3 months (DL-2 and DL-3) were compared with samples from Göttingen minipigs (GM) aged either 18 or 40 months (GM-18 and GM-40) using transmitted light (phase-contrast mode) and transmission electron microscopy. The GM-18, GM-40 and the DL-3 groups had typical muscular artery histological characteristics. Contrasting to this, the 2-month-old DL pigs had a transitional artery type being characterized by a significantly higher proportion of elastic fibres and a significantly lower number of smooth muscle cells than did the 1 month older DL-3. During the period of maturation, the tunica media of the CCA in GM animals thickened by 1.3× and in DL animals by 2.5× resulting in an overall increased vessel wall thickness. The cumulated thickness of the tunica interna (endothelium, stratum subendotheliale and internal elastic lamina) and the tunica media (including the external elastic lamina) of DL-3 and GM-40 pigs were similar to each other and comparable to that of humans. With an increasing vessel wall thickness, the luminal diameter decreased in GM by 19% and in DL by 11%. Additionally, in the older age groups, GM-40 and DL-3, the internal elastic lamina principally was continuous, but there were also interrupted large segments of elastic lamina separated by gaps. In addition, the principal internal elastic lamina was duplicated in several places.