Proline dehydrogenase is the rate-limiting enzyme in proline degradation and serves important functions in the stress responses and development of plants. We isolated two tobacco proline dehydrogenases, NtPDH1 and NtPDH2, in the course of screening for genes upregulated in stressed tobacco (Nicotiana tabacum) microspores. Expression analysis revealed that the two genes are differentially regulated. Under unstressed conditions, their steady-state transcript levels were similar in mature pollen and apical meristems, whereas NtPDH2 was expressed predominantly in vegetative organs, styles, and ovules. The expression of NtPDH1 was maintained at a constant low level during 24 h of dehydration, whereas NtPDH2 was upregulated within 1 h after the onset of stress and subsequently downregulated to undetectable levels. Differential and sustained expression was also found for the two enzymatic isoforms of Arabidopsis thaliana AtPDH. Silencing of the NtPDH genes by RNA interference using the CaMV 35S promoter led to increased proline contents, decreased seed set, delayed seed germination and retarded seedling development pointing towards an important function of at least one of the two NtPDH genes during plant reproductive development.

Modern European beekeeping is facing numerous challenges due to a variety of factors, mainly related to globalisation, agrochemical pollution and environmental changes. In addition to this, new pathogens threaten the health of European honeybees. In that context, correct colony management should encompass a wider vision, where productivity aspects are linked to a One Health approach in order to protect honeybees, humans and the environment. This paper describes a novel tool to be applied in beekeeping operations: good beekeeping practices (GBPs). The authors ranked a list of GBPs scored against their importance and validated by an international team, including researchers, national animal health authorities and international beekeepers' associations. These activities were carried out in the project 'BPRACTICES', approved within the transnational call of the European Research Area Network on Sustainable Animal Production Rev. Sci. Tech. Off. Int. Epiz., 38 (3) 3 3/27 (ERA-NET SusAn) in the Horizon 2020 research and innovation programme of the European Union. This study, created through an international collaboration, aims to present an innovative and implementable approach, similar to applications already adopted in other livestock production systems.

SummaryReversible male sterility and doubled haploid plant production are two valuable technologies in F 1 -hybrid breeding. F 1 -hybrids combine uniformity with high yield and improved agronomic traits, and provide self-acting intellectual property protection. We have developed an F 1 -hybrid seed technology based on the metabolic engineering of glutamine in developing tobacco anthers and pollen. Cytosolic glutamine synthetase (GS1) was inactivated in tobacco by introducing mutated tobacco GS genes fused to the tapetum-specific TA29 and microspore-specific NTM19 promoters. Pollen in primary transformants aborted close to the first pollen mitosis, resulting in male sterility. A non-segregating population of homozygous doubled haploid male-sterile plants was generated through microspore embryogenesis.Fertility restoration was achieved by spraying plants with glutamine, or by pollination with pollen matured in vitro in glutamine-containing medium. The combination of reversible male sterility with doubled haploid production results in an innovative environmentally friendly breeding technology. Tapetum-mediated sporophytic male sterility is of use in foliage crops, whereas microspore-specific gametophytic male sterility can be applied to any field crop. Both types of sterility preclude the release of transgenic pollen into the environment.