Abstract: [Objective] This study aimed to reveal the change pattern of endogenous hormones content and volatile compounds in Masson pine seedlings under drought stress, and to provide a foundation for studying the stress-resistance physiology and nursery of Masson pine.[Method] The seedling volatiles, under different drought stress, were identified by headspace solid phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS), and the endogenous hormones were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS).[Result] A total of 13 types of volatiles were identified with GC-MS, they belong to terpenoids, aldehydes, alcohols, and ester compounds. Nine types were identified as terpenoids, and among them, α-pinene, caryophyllene, and α-phellandrene had relatively higher content. Under drought stress, relative content of monoterpenes decreased first and then increased as the drought stress intensified, but relative content of sesquiterpenes increased first and then decreased. Drought conditions promoted the synthesis of monoterpenes. The content of ABA and ZT in needles was gradually increased with the strengthening of drought stress, but GA and IAA content was decreased gradually with the strengthening of drought stress.[Conclusion] HS-SPME could be one of the effective techniques to extract the volatiles of Masson pine under drought stress condition, and GC-MS is suitable for the needle volatiles identification. Under drought stress, Masson pine needles are rich in monoterpenes and sesquiterpenes. Through altering the ratio of monoterpenes and sesquiterpenes, seedlings enhanced the drought resistance. Endogenous hormones improved the drought-resistant ability to adapt the drought stress through coordination with each other. ZT and ABA are important hormones of drought stress, and deserve further study.

Key words: Pinus massoniana, drought stress, volatiles, endogenous hormones