No abstract

Gibberellins (GAs) are involved in the regulation of numerous developmental processes in plants including zygotic embryogenesis, but their biosynthesis and role during somatic embryogenesis (SE) is mostly unknown. In this study we show that during three week- long induction phase, when cells of leaf explants from non-embryogenic genotype (M9) and embryogenic variant (M9-10a) were forming the callus, all the bioactive gibberellins from non-13-hydroxylation (GA4, GA7) and 13-hydroxylation (GA1, GA5, GA3, GA6) pathways were present, but the contents of only a few of them differed between the tested lines. The GA53 and GA19 substrates synthesized by the 13-hydroxylation pathway accumulated specifically in the M9-10a line after the first week of induction; subsequently, among the bioactive gibberellins detected, only the content of GA3 increased and appeared to be connected with acquisition of embryogenic competence. We fully annotated 20 Medicago truncatula orthologous genes coding the enzymes which catalyze all the known reactions of gibberellin biosynthesis. Our results indicate that, within all the genes tested, expression of only three: MtCPS, MtGA3ox1 and MtGA3ox2, was specific to embryogenic explants and reflected the changes observed in GA53, GA19 and GA3 contents. Moreover, by analyzing expression of MtBBM, SE marker gene, we confirmed the inhibitory effect of manipulation in GAs metabolism, applying exogenous GA3, which not only impaired the production of somatic embryos, but also significantly decreased expression of this gene.

However, the callus formation was observed in the nonembryogenic line as well, but the LEC1 and L1L genes were not expressed and the transcription of PRC2 genes was at stable level. It was only the SWN expression that decreased at the beginning of induction and did not change in the subsequent days in both lines. Our results indicate that LEC1 and L1L, known as marker genes of the late developmental stages, may be associated with the acquisition of embryogenic competency by somatic cells (prime events in the SE induction). The PRC2 complex genes are also expressed during embryogenic callus tissue formation on Medicago tuncatula leaf explants.

No abstract

The subject of the article is the last period of General Aleksei Brusilov’s military activity – during the civil war as well as active service in the Red Army. Focus has been placed mainly on the years 1923–1924, when he served in the Soviet forces as General Inspector of the Cavalry, contributing to its increasing professionalization. Due to the lack of any studies on Brusilov in Polish, the author considered it necessary to present an outline of the general’s military career in the army of the Russian Empire until 1914, which gave the paper a more comprehensive character and made it possible to critically assess his command and organizational skills. A brief discussion of the evolution of General Brusilov’s image in historiography and USSR and Russian propaganda has also been included.