The Physiological Mechanism(s) of Needle Abscission Resistance in Root Detached Balsam Fir

香脂冷杉的针叶损失威胁着价值9700万美元的大西洋加拿大圣诞树和绿色产业的生存。针滴的确切原因尚不清楚。具有高抗针尖脱落性的无性系尚待鉴定和开发。离根香脂杉木抗针尖脱落的解剖、生理机制尚不清楚。针尖脱落的引发因素、信号和调制器也不清楚。本项目将鉴定出抗脱针能力增强的克隆，发现脱针和调控的启动因子、信号、机制和调节因子。我们认为，RD香脂冷杉的针落是由多种胁迫（脱水、机械和极端温度）引发的，触发了复杂而未知的细胞信号，涉及多种植物激素和/或某些挥发物，促进了一系列衰老反应，导致某些细胞壁成分在附着点溶解，促进脱落。本项目将对苦瓜冷杉的病因、信号、针尖脱落生理及抗针尖脱落机制等方面进行研究。了解这些过程将有助于筛选和鉴定具有更强的针脱落抗性的基因型，并开发控制针损失的技术，这直接有助于圣诞树产业的可持续性，以保持其竞争地位，并为加拿大的生物经济和人力资源发展做出贡献。

Needle loss in Balsam fir threatens the survival of the 97 million dollar Atlantic Canada Christmas Tree and Greenery industry. The exact cause of needle drop is not known. Clones with high needle abscission resistance are yet to be identified and developed. The anatomical, physiological mechanisms of needle abscission resistance in root detached (RD) Balsam fir are yet to be uncovered. The initiators, the signals and the modulators of needle abscission are also not known. This project will identify the clones with enhanced needle abscission resistance and discover the initiators, signals and the mechanism and the modulators of needle abscission and regulation. We propose that needle drop in RD Balsam fir is initiated by multiple stresses (dehydration, mechanical and extreme temperatures), triggering complex yet unknown cellular signals, involving multiple plant hormones and/or certain volatiles, promoting a cascade of senescence reactions, resulting in dissolution of certain cell wall components at the point of attachment, promoting abscission. This project will lead to several discoveries relating to causal factor, signals, needle abscission physiology and needle abscission resistance mechanism(s) of RD Balsam fir. An understanding of these processes will help to screen and identify the genotypes with enhanced needle abscission resistance and develop technologies to control needle loss contributing directly to the sustainability of the Christmas tree industry to retain its competitive position and contribute to Canadian bioeconomy and human resource development.