Many plant species are able to regenerate adventitious roots either directly from aerial organs such as leaves or stems, in particularly after detachment (cutting), or indirectly, from over-proliferating tissue termed callus. In agriculture, this capacity of de novo root formation from cuttings can be used to clonally propagate several important crop plants including cassava, potato, sugar cane, banana and various fruit or timber trees. Direct and indirect de novo root regeneration (DNRR) originates from pluripotent cells of the pericycle tissue, from other root-competent cells or from non-root-competent cells that first dedifferentiate. Independently of their origin, the cells convert into root founder cells, which go through proliferation and differentiation subsequently forming functional root meristems, root primordia and the complete root. Recent studies in the model plants Arabidopsis thaliana and rice have identified several key regulators building in response to the phytohormone auxin transcriptional networks that are involved in both callus formation and DNRR. In both cases, epigenetic regulation seems essential for the dynamic reprogramming of cell fate, which is correlated with local and global changes of the chromatin states that might ensure the correct spatiotemporal expression pattern of the key regulators. Future approaches might investigate in greater detail whether and how the transcriptional key regulators and the writers, erasers, and readers of epigenetic modifications interact to control DNRR.

Polycomb group (PcG) protein-mediated histone methylation (H3K27me3) controls the correct spatiotemporal expression of numerous developmental regulators in Arabidopsis. Epigenetic silencing of the stem cell factor WUS in floral meristems (FMs) depends on H3K27me3 deposition by PcG proteins. However, the role of H3K27me3 in silencing of other meristematic regulator and pluripotency genes during FM determinacy has not yet been studied. To this end, we report the genome-wide dynamics of H3K27me3 levels during FM arrest and the consequences of strongly depleted PcG activity on early flower morphogenesis including enlarged and indeterminate FMs. Strong depletion of H3K27me3 levels results in misexpression of the FM identity gene AGL24, which partially leads to floral reversion causing ap1-like flowers and indeterminate FMs expressing ectopically WUS and STM. Loss of STM can rescue supernumerary floral organs and FM indeterminacy in H3K27me3-deficient flowers indicating that the hyperactivity of the FMs is at least partially a result of ectopic STM expression. Nonetheless, WUS remained essential for the FM activity. Our results demonstrate that PcG proteins promote FM determinacy at multi-levels of the floral gene regulatory network, silencing initially floral regulators like AGL24 that promotes FM indeterminacy, and subsequently, meristematic pluripotency genes such as WUS and STM during FM arrest.

Plant leaf margins produce small outgrowths or teeth causing serration in a regular arrangement, which is specified by auxin maxima. In Arabidopsis, the spatiotemporal pattern of auxin dependents on both, the transcription factor CUC2 and the signal peptide EPFL2, a ligand of the growth-promoting receptor kinase ERECTA (ER). Ectopic expression of CUC2 can have contrary effects on leaf growth. Ubiquitous expressed CUC2 suppresses growth in the whole leaf, whereas cuc2-1D mutants have enlarged leaves, through ER-dependent cell proliferation in the teeth. Here we investigated the growth dynamics of cuc2-1D leaves and the growth restricting the function of CUC2 using the ubiquitous inducible CUC2-GR transgene. In time courses, we dissected the serration promoting the function of CUC2 in the leaf margin and ectopic growth inhibition by CUC2 in the leaf plate. We found that CUC2 limits growth rather by cell cycle inhibition than by cell size control. Furthermore, endogenous CUC2 was rapidly induced by CUC2-GR indicating a possible auto-inducible feedback. In contrast, EPFL2 was quickly decreased by transient CUC2 induction but increased in cuc2-3 mutant leaves suggesting that CUC2 can also counteract the EPFL2-ER pathway. Therefore, tooth growth promotion and growth inhibition by CUC2 involve partially the same mechanism but in contrary ways.

Sacha Inchi (Plukenetia volubilis Linneo, Euphorbiaceae) is known as a Peruvian seed containing a high level of unsaturated fatty acids, such as α-linolenic acid (Omega-3), linoleic acid (Omega-6), and oleic acid (Omega-9). These essential fatty acids are important functional foods due to their benefits for human health. Considering its benefits, it is necessary to find the right cultivation conditions to develop Sacha Inchi in Indonesia, where it has not been widely cultivated. This study aimed to determine the adaptability of Sacha Inchi to different cultivation conditions and the effects of these conditions on seed production and oil quality. Sacha Inchi plants were cultivated under three different cultivation conditions (open area, mixed cultures, and agroforestry) and the seeds were harvested monthly to determine the seed production and oil quality. The results showed that seed production in the open area was higher than in other conditions. The highest oil yield from monthly harvesting was found in mixed cultures. Interestingly, the level of Omega-3 content in the agroforestry condition was higher compared to other conditions. The level of Omega-6 and Omega-9 content in the open area was higher than in mixed cultures and agroforestry. However, the content of unsaturated fatty acids in the three different cultivation conditions was not significantly different, being 91.88% in the open area, 92.53% in mixed cultures, and 92.97% for agroforestry. In conclusion, the cultivation of Sacha Inchi under open areas is recommended due to its seed productivity which will affect the total oil production.