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PubMed2026

The larch DAL1 interacts with PEBP family genes to regulate the annual growth cycle.

Boreal and temperate perennial woody plants coordinate annual growth cycle with seasonal environmental changes with age-dependent phenological differences. However, the underlying molecular mechanisms remain limited. In this study, we demonstrated that the MADS-box transcription factor DAL1 in Larix kaempferi (Japanese larch) directly regulates the expression of PEBP family genes LkFT1 and LkMFT to govern the annual growth cycle. LkDAL1 binds to the LkFT1 promoter to repress its expression, and to the LkMFT promoter to activate its expression. LkFT1 is highly expressed in the dormant stage, with its expression increased by short day and decreased by winter low temperature and subsequent spring warm temperature, whereas LkMFT is highly expressed in the active stage, with its expression decreased by short day. Notably, when it comes to tree age, LkFT1 is highly expressed in dormant young trees, LkMFT is highly expressed in active adult trees, and LkDAL1 expression levels increase with age in both dormant and active trees. Further, transient overexpression of LkFT1 in dormant larch delays bud break, that of LkMFT promotes bud break, and that of LkDAL1 promotes bud break; in addition, stable overexpression of LkDAL1 in poplar also promotes bud break. Moreover, overexpression of LkFT1 or LkMFT promotes flowering in Arabidopsis thaliana. Together, these findings uncover a novel mechanism in which the LkDAL1-PEBP module regulates the annual growth cycle in larch, providing new insights into age-dependent phenological differences in conifers.

Larix↗

PubMed1977

The time and duration of meiosis.

Ever since meiosis was recognized as a process there has been a continuing interest in its temporal aspects. Two main types of meiotic timing experiments have been conducted: first, experiments to estimate the duration of meiosis (and sometimes its stages); second, experiments to locate the sensitive stage(s) when exposure of meiocytes to various treatments can affect meiotic chromosome behaviour (e.g. pairing or recombination). Such experiments have played an important role in increasing our understanding of the meiotic process. The duration of meiosis has been estimated in about 70 organisms, including two prokaryotes (yeast and Chlamydomonas) and the following eukaryotes: 1 Basidiomycete (Coprinus lagopus), 2 Gymnosperms (Larix decidua and Thuja plicata gracilis). at least 39 angiosperms, and at least 26 animal species. The duration of female meiosis has been estimated in far fewer species than male meiosis. However, estimates of the duration of female meiosis are available for 6 angiosperms. Drosophila melanogaster, Xenopus laevis, and several mammals. Comparison of these data shows that the duration of meiosis is one of the most variable aspects of the meiotic process, ranging from less than 6 h in yeast to more than 40 years in the human female. Developmental holds at different stages of meiosis are common in plants and animals, and inevitably prolong the meiotic division. However, even among species without developmental holds, the duration of meiosis is very variable. For instance, in animals it ranges from about 1-2 days in male Drosophila melanogaster to more than 24 days in male Homo sapiens and several Orthopterans. Despite the large variation in the duration of meiosis three generalizations can be made: (i) first prophase is always very long compared with the remaining meiotic stages, (ii) the rate of meiotic development is very slow compared with the rate of development in dividing somatic meristem cells of the same organisms under the same conditions, (iii) the duration of meiosis is characteristic of the genotype and species. Four main factors have been recognized which effect or determine the duration of meiosis, namely (1) environmental factors (e.g. temperature); (2) nuclear DNA content; (3) ploidy level of the organism; and, (4) the genotype. Because nuclear DNA content plays a major role in determining the duration of meiosis, it has been suggested that DNA influences the rate of meiotic development in two ways: first through its informational content (the genotype), and second indirectly by the physical and mechanical effects of its mass independently of its informational content (i.e. the nucleotype). Thus, the observed duration of meiosis is the result of a complex genotype-nucleotype-environment interaction. With the obvious exception of variation caused by developmental holds, changes in the duration of meiosis usually involve proportional changes in the durations of all its stages...

Animals↗