Phase change refers to the process of maturation and transition from the juvenile to the adult stage. In response to this shift, certain species like chestnut lose the ability to form adventitious roots, thereby hindering the successful micropropagation of adult plants. While auxin is the main hormone involved in adventitious root formation, other hormones, such as ethylene, are also thought to play a role in its induction and development. In this study, experiments were carried out to determine the effects of ethylene on the induction and growth of adventitious roots. The analysis was performed in two types of chestnut microshoots derived from the same tree, a juvenile-like line with high rooting ability derived from basal shoots (P2BS) and a line derived from crown branches (P2CR) with low rooting responses. By means of the application of compounds to modify ethylene content or inhibit its signalling, the potential involvement of this hormone in the in-duction of adventitious roots was analyzed. Our results show that ethylene can modify the rooting competence of mature shoots, while the response in juvenile material was barely affected. To further characterize the molecular reasons underlying this maturation-derived shift in behaviour, specific gene expression analyses were developed. Findings suggest that several mechanisms, including ethylene signalling, auxin transport and epigenetic modifications, relate to the modu-lation of the rooting ability of mature chestnut microshoots and their recalcitrant behaviour.

A positive fluid balance may evolve to fluid overload and associate with organ dysfunctions, weaning difficulties, and increased mortality in ICU patients. We explored whether individualized fluid management, assessing fluid-responsiveness via passive leg-raising maneuver (PLR) before spontaneous breathing trial (SBT) associated with less extubation failure in ventilated patients with high fluid balance, admitted to the ICU after liver transplantation (LT). We recruited 15 LT patients in 2023. Postoperative fluid balance was +4476 [3697,5722] mL. PLRs were conducted at ICU admission (T1) and pre-SBT (T2). Cardiac index (CI) changes were recorded before and after SBT (T3). Seven patients were fluid responsive at T1, and 12 at T2. No significant differences occurred in hemodynamic, respiratory, and perfusion parameters between fluid-responsive and fluid-unresponsive patients at any time. Fluid-responsive patients at T1 and T2 increased their CI during SBT from 3.1 [2.8,3.7] to 3.7 [3.4,4.1] mL/min/m2 (p= 0.045). All fluid-responsive patients at T2 were extubated after SBT and consolidated extubation. Two out of three of fluid-unresponsive patients experienced weaning difficulties. We concluded that fluid-responsive patients post-LT may start weaning earlier and achieve successful extubation despite high postoperative fluid balance. This highlights the profound impact of personalized assessment of cardiovascular state on critical surgical patients.

Wounding and exogenous auxin are needed to induce adventitious roots in Chestnut microshoots. However, the specific inductive role of wounding has not been characterized in this species. In the present work two main goals were established: First, we prompted to optimize exogenous auxin treatments to improve overall health status of the shoots at the end of the rooting cycle. Second, we developed a time-series transcriptomic analysis to compare gene expression in response to wounding alone and wounding plus auxin, focusing in the early events within the first days after treatments. Results suggest that the expression of many genes involved in the rooting process is under direct or indirect control of both stimuli. However, specific levels of expression of relevant genes are only attained when both treatments are applied simultaneously, leading to the successful development of roots. In this sense, we have identified four transcription factors upregulated by auxin (CsLBD16, CsERF113, Cs22D, CsIAA6), with some of them being also induced by wounding. The highest expression levels of these genes occurred when wounding and auxin treatments were applied simultaneously, correlating with the rooting response of the shoots. Results in this work clarify the genetic nature of the wounding response in chestnut, its relation to adventitious rooting and might be helpful in the development of more specific protocols for the vegetative propagation of this species.