Microtubule configurations and nuclear DNA synthesis during initiation of suspensor-bearing embryos from Brassica napus cv. Topas microspores

In the new Brassica napus microspore culture system, wherein embryos with suspensors are formed, ab initio mimics zygotic embryogenesis. The system provides a powerful in vitro tool for studying the diverse developmental processes that take place during early stages of plant embryogenesis. Here, we studied in this new culture system both the temporal and spatial distribution of nuclear DNA synthesis places and the organization of the microtubular (MT) cytoskeleton, which were visualized with a refined whole mount immunolocalization technology and 3D confocal laser scanning microscopy. A ‘mild’ heat stress induced microspores to elongate, to rearrange their MT cytoskeleton and to re-enter the cell cycle and perform a predictable sequence of divisions. These events led to the formation of a filamentous suspensor-like structure, of which the distal tip cell gave rise to the embryo proper. Cells of the developing pro-embryo characterized endoplasmic (EMTs) and cortical microtubules (CMTs) in various configurations in the successive stages of the cell cycle. However, the most prominent changes in MT configurations and nuclear DNA replication concerned the first sporophytic division occurring within microspores and the apical cell of the pro-embryo. Microspore embryogenesis was preceded by pre-prophase band formation and DNA synthesis. The apical cell of the pro-embryo exhibited a random organization of CMTs and, in relation to this, isotropic expansion occurred, mimicking the development of the apical cell of the zygotic situation. Moreover, the apical cell entered the S phase shortly before it divided transversally at the stage that the suspensor was 3–8 celled

Presence of celiac disease epitopes in modern and old hexaploid wheat varieties: wheat breeding may have contributed to increased prevalence of celiac disease

Gluten proteins from wheat can induce celiac disease (CD) in genetically susceptible individuals. Specific gluten peptides can be presented by antigen presenting cells to gluten-sensitive T-cell lymphocytes leading to CD. During the last decades, a significant increase has been observed in the prevalence of CD. This may partly be attributed to an increase in awareness and to improved diagnostic techniques, but increased wheat and gluten consumption is also considered a major cause. To analyze whether wheat breeding contributed to the increase of the prevalence of CD, we have compared the genetic diversity of gluten proteins for the presence of two CD epitopes (Glia-α9 and Glia-α20) in 36 modern European wheat varieties and in 50 landraces representing the wheat varieties grown up to around a century ago. Glia-α9 is a major (immunodominant) epitope that is recognized by the majority of CD patients. The minor Glia-α20 was included as a technical reference. Overall, the presence of the Glia-α9 epitope was higher in the modern varieties, whereas the presence of the Glia-α20 epitope was lower, as compared to the landraces. This suggests that modern wheat breeding practices may have led to an increased exposure to CD epitopes. On the other hand, some modern varieties and landraces have been identified that have relatively low contents of both epitopes. Such selected lines may serve as a start to breed wheat for the introduction of ‘low CD toxic’ as a new breeding trait. Large-scale culture and consumption of such varieties would considerably aid in decreasing the prevalence of CD

A systems biology approach to browning in apple - influence of harvest date on the proteome

During long term storage of apple (Malus x domestica Borkh.), physiological disorders may occur. One major group of internal disorders is characterized by flesh browning. The susceptibility to flesh browning is cultivar, batch and season dependent and is caused by a combination of preharvest and postharvest factors. This can result in considerable economic losses with incidence levels up to 40%. Braeburn and Kanzi are commercial cultivars in Belgium that are prone to browning. Harvest date is known to affect the sensitivity of a batch to browning during subsequent storage. The main objective of this experiment is to investigate how the proteome of apples differs in function of their harvest date. This will be related to browning incidence after prolongued storage. Apples (Malus x domestica Borkh., cv. Braeburn) were picked in the orchard of the Experimental Garden for Pome and Stone Fruits, pcfruit (Sint-Truiden, Belgium) at three different harvest times. Proteins were extracted immediately after harvest, using a phenol extraction (Pedreschi et al. 2007) and quantified using a modified Bradford procedure. For each harvest time five replicate extracts were prepared and analysed after tryptic digestion using a nano-2D_UPLC-MS system, Synapt Q-TOF. Data processing was performed with ProteinLynx and Progenesis software. After optimization of the peptide extraction and two-dimensional separation, 24439 peptides could be detected and 145 different protein families could confidentially be identified via an optimized workflow (Vertommen et al in press). Further results will be presented focusing on the observed proteome differences as a function of harvest date.status: publishe