The success of the first meiotic division relies (among other factors) on the formation of bivalents between homologous chromosomes, the monopolar orientation of the sister kinetochores at metaphase I and the maintenance of centromeric cohesion until the onset of anaphase II. The meiotic cohesin subunit, Rec8 has been reported to be one of the key players in these processes, but its precise role in kinetochore orientation is still under debate. By contrast, much less is known about the other non-SMC cohesin subunit, Scc3. We report the identification and the characterisation of AtSCC3, the sole Arabidopsis homologue of Scc3. The detection of AtSCC3 in mitotic cells, the embryo lethality of a null allele Atscc3-2, and the mitotic defects of the weak allele Atscc3-1 suggest that AtSCC3 is required for mitosis. AtSCC3 was also detected in meiotic nuclei as early as interphase, and bound to the chromosome axis from early leptotene through to anaphase I. We show here that both AtREC8 and AtSCC3 are necessary not only to maintain centromere cohesion at anaphase I, but also for the monopolar orientation of the kinetochores during the first meiotic division. We also found that AtREC8 is involved in chromosome axis formation in an AtSPO11-1-independent manner. Finally, we provide evidence for a role of AtSPO11-1 in the stability of the cohesin complex.

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Successful commercial utilization of the meal by-product of Brassica oilseed crops requires the cultivation of cultivars with low glucosinolate (GSL) content in the seeds; however, such cultivars are not yet available in Brassica carinata. The objective of the present research was to search for transgressive segregants with further-reduced GSL content in the progeny of crosses involving four B. carinata lines with reduced GSL content (90 compared with 120 lmol/g seed in standard germplasm). The four lines were crossed following a diallel design and F 2 phenotypes (F 3 seed bulked) were analysed for GSL content. F 2 phenotypes with a transgressive GSL content lower than the parents were identified in all crosses involving the line S2-1241, suggesting that this line carries alleles for reduced GSL content not present in the other lines. F 3 : 4 lines from transgressive F 2 phenotypes were evaluated for 2 years, which resulted in the selection of an F 3 : 4 line with an average GSL content of 58 and 46 lmol/g seed, respectively compared with 84 and 62 lmol/g seed, respectively in S2-1241.

Seed meal amendments rich in glucosinolates are of interest for soil pest and disease control. The Ethiopian mustard (Brassica carinata A. Braun) line N2-6215, with very high levels of seed glucosinolates (160 lmol/g), was developed from the line C-101 (116 lmol/g) following mutagenesis. The objective of this research was to study the inheritance of very high seed glucosinolate content. Plants of N2-6215 were reciprocally crossed with plants of the line C-101. The F 1 , F 2 , and BC 1 F 1 plant generations were evaluated in two environments and seeds from individual plants were analysed for total glucosinolate content. The very high glucosinolate content in N2-6215 seeds was largely subject to maternal control. No cytoplasmic effects were detected. The trait was found to be oligogenic and determined by at least two or three genes. The estimates of broad-sense heritability were 0.45 and 0.58 in both environments, whereas the estimates of narrowsense heritability were 0.35 and 0.50. The moderate heritability and oligogenic control of the trait suggest the feasibility of breeding for increased seed glucosinolate content in Ethiopian mustard.

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