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加拿大大西洋圣诞树和绿化产业的生存。针头脱落的确切原因尚不清楚。具有高抗针叶脱落性的克隆尚待鉴定和开发。离根香脂冷杉抗针叶脱落的解剖学、生理学机制尚未完全阐明。针发射的启动器、信号和调节器也是未知的。本项目将鉴定具有增强的针叶脱落抗性的克隆，并发现针叶脱落和调节的启动子、信号、机制和调节剂。我们认为RD香脂冷杉的落针是由多重压力（脱水，机械和极端温度）引发的，触发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，促进衰老反应的级联，导致某些细胞壁成分在附着点溶解，促进脱落。该项目将导致与RD香脂冷杉的因果因素、信号、针叶脱落生理和针叶脱落抗性机制有关的几个发现。了解这些过程将有助于筛选和确定具有增强的针叶脱落抗性的基因型，并开发控制针叶损失的技术，直接有助于圣诞树行业的可持续性，以保持其竞争地位，并有助于加拿大生物经济和人力资源开发。

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.