Genetic analysis reveals three novel QTLs underpinning a butterfly egg-induced hypersensitive response-like cell death in Brassica rapa.

BACKGROUND: Cabbage white butterflies (Pieris spp.) can be severe pests of Brassica crops such as Chinese cabbage, Pak choi (Brassica rapa) or cabbages (B. oleracea). Eggs of Pieris spp. can induce a hypersensitive response-like (HR-like) cell death which reduces egg survival in the wild black mustard (B. nigra). Unravelling the genetic basis of this egg-killing trait in Brassica crops could improve crop resistance to herbivory, reducing major crop losses and pesticides use. Here we investigated the genetic architecture of a HR-like cell death induced by P. brassicae eggs in B. rapa. RESULTS: A germplasm screening of 56 B. rapa accessions, representing the genetic and geographical diversity of a B. rapa core collection, showed phenotypic variation for cell death. An image-based phenotyping protocol was developed to accurately measure size of HR-like cell death and was then used to identify two accessions that consistently showed weak (R-o-18) or strong cell death response (L58). Screening of 160 RILs derived from these two accessions resulted in three novel QTLs for Pieris brassicae-induced cell death on chromosomes A02 (Pbc1), A03 (Pbc2), and A06 (Pbc3). The three QTLs Pbc1-3 contain cell surface receptors, intracellular receptors and other genes involved in plant immunity processes, such as ROS accumulation and cell death formation. Synteny analysis with A. thaliana suggested that Pbc1 and Pbc2 are novel QTLs associated with this trait, while Pbc3 also contains an ortholog of LecRK-I.1, a gene of A. thaliana previously associated with cell death induced by a P. brassicae egg extract. CONCLUSIONS: This study provides the first genomic regions associated with the Pieris egg-induced HR-like cell death in a Brassica crop species. It is a step closer towards unravelling the genetic basis of an egg-killing crop resistance trait, paving the way for breeders to further fine-map and validate candidate genes.

Student participation in governance of medical and veterinary education: experiences and perspectives of student representatives and program directors.

Student participation in governance of education is of growing interest. However, it remains unclear what factors render this participation in institutional governance a success or a failure. Another question is: what are the perceived benefits for schools and students? We empirically explored experiences and perspectives of student representatives and program directors of all (8) medical and (1) veterinary schools in the Netherlands on factors that influence student participation in institutional governance and its values and challenges for schools and student representatives. A constructivist grounded theory study was performed. A theoretical sample of student representatives was invited to fill out an explorative, qualitative questionnaire. Next, focus groups with student representatives and interviews with all program directors were conducted. Data was analyzed using open, axial and selective coding by all authors. Experiences and perspectives of students and program directors were remarkably similar in both perceived influences and values. Four main categories of influences could be distinguished in student participation: (1) individual student characteristics, (2) individual staff characteristics, (3) the organization of student representatives and (4) the school's organization, including its culture and policy regarding student participation. A cohesive, well-organized and independent student organization has crucial impact on student participation in educational governance processes. For representatives, major benefits of participation are personal and career development. Challenges are low effectiveness and efficiency of their actions. A clear school policy on student participation and better introduction, feedback and coaching of representatives should be provided to improve student participation in governance processes.