王尧，董帅，张民，李振华

摘  要：為了解烟草种子光休眠与后熟的分子机理，本研究以野生型（WT）、NtPHYB1过表达（NtPHYB1-OE）和NtPHYB1 RNA干扰（NtPHYB1-RNAi）3种烟草种子为材料，在恒温和变温2种环境下进行后熟。结果表明，与WT新采收种子相比，NtPHYB1-RNAi新采收种子光休眠显著加深，而NtPHYB1-OE新采收种子光休眠未显著变浅。与恒温后熟相比，变温下WT和NTPHYB1-OE种子后熟加快，而NTPHYB1-RNAi种子变化不显著。与WT新采收种子相比，NtPHYB1-RNAi新采收种子中NtABI3的表达量显著提高，NtPHYB1-OE新采收种子中NtABI5的表达量显著降低。在变温下后熟，WT种子中NtNCED6和NtGA2ox2下降变缓，NtCYP707A1和 NtGA3ox2上升变缓;NtPHYB1-RNAi种子中NtNCED6下降变缓，而NtCYP707A1上升变缓;NtPHYB1-OE种子中NtNCED6下降变缓，而NtCYP707A1、NtGA3ox2、NtGA2ox2和NtGAI下降均加快。综上所述，NtPHYB1能够协同储藏温度影响ABA和GA的信号和代谢基因表达从而调控种子光休眠和后熟。

关键词：光休眠;后熟;NtPHYB1;变温;种子萌发;植物激素

NtPHYB1 Interacts with Storage Temperature to Regulate Seed Photodormancy and After-ripening in Nicotiana tabacum L.

WANG Yao， DONG Shuai， ZHANG Min， LI Zhenhua*

（College of Agronomy， Guizhou University， Guiyang 550025， China）

Abstract： To reveal the molecular mechanism of seed photodormancy and after-ripening in tobacco， wild-type （WT）， NtPHYB1 over expression （NtPHYB1-OE） and deficient （NtPHYB1-RNAi） tobacco seeds were used in this study， in conducting after-ripening experiments in two environments with constant or natural temperature. The results showed that NtPHYB1-RNAi fresh seeds had a significant increase in photodormant level compared with WT fresh seeds; However， the photodormancy of NtPHYB1-OE fresh seeds did not show significant change. The after-ripening of WT and NtPHYB1-OE seeds was accelerated under variable temperature compared with under constant temperature storage， while that of NtPHYB1-RNAi seeds was not significantly changed. Compared with WT fresh seeds， the expression of NtABI3 in NtPHYB1-RNAi fresh seeds was significantly increased， while the expression of NtABI5 in NtPHYB1-OE fresh seeds was significantly decreased. In WT seeds， expression of NtNCED6 and NtGA2ox2 decreased slowly when after-ripening under variable temperature， while NtCYP707A1 and NtGA3ox2 were up-regulated slowly. In NtPHYB1-RNAi seeds， NtNCED6 expression decreased slowly then， while NtCYP707A1 expression increased slowly. In NtPHYB1-OE seeds， NtNCED6 expression decreased slowly then， while expression of NtCYP707A1， NtGA3ox2， NtGA2ox2 and NtGAI decreased faster. In conclusion， NtPHYB1 interacts with storage temperature to regulate photodormancy and after-ripening by regulating expressions of genes involved in ABA and GA signal and metabolism in tobacco seeds.

Keywords： photodormancy; after-ripening; NtPHYB1; variable temperature; seed germination; phytochrome

种子光休眠（photodormancy）是指具有生活力的种子在黑暗环境下暂时不能萌发的现象。至今，已经在上千物种中发现种子光休眠，特别是小粒种子物种，种子光休眠较为普遍。在生产上，丸化有利于小粒种子播种，但丸化后，喜光性（photophil）种子易出现光休眠，严重影响出苗率。因此，研究种子光休眠和后熟的调控机制，对于指导光敏感种子制种和播种均具有重要意义。

光照和后熟均具有解除种子休眠和促进萌发

的作用。目前关于光解除种子休眠和促进萌发的分子机制研究较为深入，它通过激发光敏色素（Phytochrome，PHY）信号通路解除种子休眠和促进萌发[1-2]。早在1934年，FLINT[3]在莴苣中发现光调控种子休眠和萌发现象。1952年，BORTHWICK等[4]发现莴苣种子萌发受红光和远红光可逆转换调控并发现PHY。……