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

香脂冷杉的针叶损失威胁到价值9700万美元的大西洋加拿大圣诞树和绿化产业的生存。针头掉落的确切原因尚不清楚。具有高抗落针能力的无性系还有待于鉴定和开发。分离根(RD)冷杉针叶脱落抗性的解剖学和生理学机制尚不清楚。针叶脱落的引发剂、信号和调制器也是未知的。该项目将鉴定具有增强的针叶脱落抗性的无性系，并发现针叶脱落和调节的启动子、信号和机制以及调节因子。我们认为，RD香脂冷杉的针滴是由多种胁迫(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，促进一系列衰老反应，导致贴壁点某些细胞壁成分的溶解，促进脱落。本项目将在马尾松的致病因子、信号、针叶脱落生理和针叶抗脱落机制(S)等方面取得若干新的发现。对这些过程的了解将有助于筛选和识别具有更强的针头脱落抗性的基因类型，并开发控制针头损失的技术，直接有助于圣诞树行业的可持续性，以保持其竞争地位，并为加拿大的生物经济和人力资源开发做出贡献。

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.