Scion–rootstock interactions influence the growth and behaviour of the grapevine root system in a heavy clay soil

Background and Aims Generally, grapevine roots have been less studied than the above‐ground parts of the plant. Here we analyse scion–rootstock interactions in mature vines growing in a heavy clay soil in a climate characterised by severe summer drought to investigate the effect of the scion–rootstock interaction in a suboptimal soil. Methods and Results The rootstocks, 34 Ecole de Montpellier, 140 Ruggeri and 1103 Paulsen, were grafted onto Nerello Mascalese and Nero d'Avola scions and assessed along with self‐rooted vines. Root distribution and root architecture were analysed using the profile wall method at 0, 60 and 120 cm from the row midline. Root density was greatest at a depth between 21 and 60 cm. The cumulative root fraction for root density registered a β value, a numerical quantity that summarises depth distribution, ranging between 0.932 and 0.962. Root number and density were significantly lower for the self‐rooted vines compared to that of the grafted vines. Conclusions The scion genotypes affected most developmental parameters, including the diameter of the root system, the root density at 21–80 cm depth and the ratio of fine roots to coarse roots. Significance of the Study The scion plays an important role in grapevine root growth, development and distribution in a heavy clay soil, although the mechanism remains unclear

Comparative transcriptome analysis of stylar canal cells identifies novel candidate genes implicated in the self-incompatibility response of Citrus clementina

<p>Abstract</p> <p>Background</p> <p>Reproductive biology in citrus is still poorly understood. Although in recent years several efforts have been made to study pollen-pistil interaction and self-incompatibility, little information is available about the molecular mechanisms regulating these processes. Here we report the identification of candidate genes involved in pollen-pistil interaction and self-incompatibility in clementine (<it>Citrus clementina </it>Hort. ex Tan.). These genes have been identified comparing the transcriptomes of laser-microdissected stylar canal cells (SCC) isolated from two genotypes differing for self-incompatibility response ('Comune', a self-incompatible cultivar and 'Monreal', a self- compatible mutation of 'Comune').</p> <p>Results</p> <p>The transcriptome profiling of SCC indicated that the differential regulation of few specific, mostly uncharacterized transcripts is associated with the breakdown of self-incompatibility in 'Monreal'. Among them, a novel F-box gene showed a drastic up-regulation both in laser microdissected stylar canal cells and in self-pollinated whole styles with stigmas of 'Comune' in concomitance with the arrest of pollen tube growth. Moreover, we identify a non-characterized gene family as closely associated to the self-incompatibility genetic program activated in 'Comune'. Three different aspartic-acid rich (Asp-rich) protein genes, located in tandem in the clementine genome, were over-represented in the transcriptome of 'Comune'. These genes are tightly linked to a DELLA gene, previously found to be up-regulated in the self-incompatible genotype during pollen-pistil interaction.</p> <p>Conclusion</p> <p>The highly specific transcriptome survey of the stylar canal cells identified novel genes which have not been previously associated with self-pollen rejection in citrus and in other plant species. Bioinformatic and transcriptional analyses suggested that the mutation leading to self-compatibility in 'Monreal' affected the expression of non-homologous genes located in a restricted genome region. Also, we hypothesize that the Asp-rich protein genes may act as Ca²⁺"entrapping" proteins, potentially regulating Ca²⁺homeostasis during self-pollen recognition.</p

Genetic diversity in Opuntia spp. cultivated for forage production

Opuntia genus belongs to the Cactaceae and includes a range of species from 75 to 250originated from the Americas. Several Opuntia species represent useful sources of forage inmany arid areas, and their cultivation is drastically increasing. However the taxonomicclassification of these species is complicated by the lack of reliable morphological descriptors,the relevant phenotypic plasticity, and the frequency of natural hybridization and of polyploidy.In this study 31 genotypes selected for forage production including Opuntia ficus-indica andsome related species were analyzed using SSR markers to establish their genetic variabilityand to elucidate phylogenetic relationships among cultivated genotypes and related species.The analysis of six loci allowed to univocally identify most of the accessions and confirmed thefact that their taxonomical classification is not congruent with the observed patterns of geneticdiversity. Most of the accessions selected for forage production were grouped exhibiting anarrow genetic variation level and clustered separately from two reference O. ficus-indicagenotypes, used for fruit production in Mediterranean area. NeighbourNet analysis displayed alow level of diversification among the forage Opuntia from Brazil suggesting they probably havecommon ancestors. This information will be useful to plan future breeding strategies aimed atthe selection of improved genotypes to be cultivated in different areas

Expression of clementine asp-rich proteins (CcASP-RICH) in tobacco plants interferes with the mechanism of pollen tube growth

Low-molecular-weight, aspartic-acid-rich proteins (ASP-RICH) have been assumed to be involved in the self-incompatibility process of clementine. The role of ASP-RICH is not known, but hypothetically they could sequester calcium ions (Ca2+) and affect Ca2+-dependent mechanisms. In this article, we analyzed the effects induced by clementine ASP-RICH proteins (CcASP-RICH) when expressed in the tobacco heterologous system, focusing on the male gametophyte. The aim was to gain insight into the mechanism of action of ASP-RICH in a well-known cellular system, i.e., the pollen tube. Pollen tubes of tobacco transgenic lines expressing CcASP-RICH were analyzed for Ca2+ distribution, ROS, proton gradient, as well as cytoskeleton and cell wall. CcASP-RICH modulated Ca2+ content and consequently affected cytoskeleton organization and the deposition of cell wall components. In turn, this affected the growth pattern of pollen tubes. Although the expression of CcASP-RICH did not exert a remarkable effect on the growth rate of pollen tubes, effects at the level of growth pattern suggest that the expression of ASP-RICH may exert a regulatory action on the mechanism of plant cell growth

Research and Application of Molecular and Phenotypic Data for Tree Biodiversity Evaluation

The main challenges for tree crop improvement are linked to the sustainable development of agro-ecological habitats, improving the adaptability to limiting environmental factors and resistance to biotic stresses or promoting novel genotypes with improved agronomic traits [...

Pollen tube behavior in different Mandarin hybrids

Seedlessness is an important trait in the evaluation of commercial mandarin for fresh consumption. However, in the last decade, the presence of seeds in fruit of cultivars considered as seedless has become a problem in different citrus-growing areas because the commercial value is depreciated. Seeds have appeared concomitantly with the introduction of new cultivars that appear to be cross-compatible. To overcome this problem, different strategies have been explored, but a definitive answer is still elusive. The search for alternatives contrasts with how little is known about the basis of the problem: the pollen-pistil incompatibility reaction in mandarin, and the intercompatibility relationship between different cultivars. In this work, we characterized the pollen-pistil incompatibility in the two commonly grown mandarin cultivars Fortune and Nova, and evaluated the intercompatibility relationship between six cultivars with different genetic origins; these cultivars included Fortune (Citrus clementina Hort. ex Tan. × Citrus reticulata Blanco), Nova [(Citrus paradisi Macf. × C. reticulata) × C. clementina), Comune Clementine (C. clementina), Avana apireno (C. reticulata), Primosole (Citrus unshiu Marcov. × C. reticulata), and Simeto (C. unshiu × Citrus deliciosa Ten.). Following the controlled hand pollination in the field, we evaluated pollen tube performance after self- and cross-pollination, as well as intercultivar compatibility by observing pollen tube growth. The results show the self-incompatibility of these cultivars with the pollen tube having been arrested in the style, which explains their seedless condition when planted in solid blocks. The study of intercompatibility indicates a different pollen tube behavior depending on the genotype, as well as on the cross combinations. These results provide a basis to evaluate self- and intercompatibility in citrus, and the effect of close planting of some cultivars.Financial support for this research was provided by the Italian Ministry of Agriculture and Forestry, Project RAVAGRU (Advanced research in citriculture), publication no. 32; by the Italian Ministry of the University, Project PRIN ‘‘The productive process in fruit tree species: molecular, physiological, and agronomical aspects of floral incompatibility and strategies for its control’’; by the Minister of Science and Innovation, EU Feder (Project grant CICYT AGL-2006-13529-CO2-01/AGR); and by the Grupo de Excelencia del Gobierno de Aragón A-43.Peer Reviewe

EST-SNP genotyping of citrus species using high-resolution melting curve analysis

'Citrus' taxonomy is very complex mainly due to specific aspects of its reproductive biology. A number of studies have been performed using various molecular markers in order to evaluate the level of genetic variability in 'Citrus'. SNP markers have been used for genetic diversity assessment using a variety of different methods. Recently, the availability of EST database and whole genome sequences has made it possible to develop more markers such as SNPs. In the present study, the high-resolution melting curve analysis (HRM) was used to detect SNPs or INDELs in 'Citrus' genus for the first time. We aimed to develop a panel of SNPs to differentiate 'Citrus' genotypes which can also be applied to 'Citrus' biodiversity studies. The results showed that 21 SNP containing markers produced distinct polymorphic melting curves among the 'Citrus' spp. investigated through HRM analysis. It was proved that HRM is an efficient, cost-effective, and accurate method for discriminating citrus SNPs as well as a method to analyze more polymorphisms in a single PCR amplicon, representing a useful tool for genetic, biodiversity, and breeding studies. SNPs developed based on 'Citrus sinensis' EST database showed a good transferability within the 'Citrus' genus. Moreover, HRM analysis allowed the discrimination of citrus genotypes at specific level and the resulting genetic distance analysis clustered these genotypes into three main branches. The results suggested that the panel of SNP markers could be used in a variety of applications in citrus biodiversity assessment and breeding programs using HRM analysis

QUANTITATIVE STRUCTURAL-ANALYSIS OF PERIPHERAL AIRWAYS AND ARTERIES IN SUDDEN FATAL ASTHMA

Abstract The peripheral airways and the adjacent muscular pulmonary arteries were studied by morphometric methods in the autopsy lungs of six asthmatic subjects who died suddenly during an asthma attack, and they were compared with those of six control subjects who died of other causes and had no history of respiratory diseases. Bronchioles of asthmatic subjects had an increased amount of lumen occlusion (p less than 0.01), smooth muscle thickness (p less than 0.001), and inflammatory infiltrate (p less than 0.001), and both mononuclear cells and eosinophils contributed to this increased inflammation. The muscular pulmonary arteries adjacent to occluded and inflamed bronchioles did not have the morphologic features of chronic hypoxia, as shown by the normal medial and intimal thickness, but they had an important inflammatory process in their walls that was particularly marked at sites adjacent to airways. Although the functional significance of these findings is unknown, they may be responsible in part for the gas exchange abnormalities observed in acute severe asthma