Huarte Hector R, Puglia Giuseppe D, Prjibelski Andrey D, Raccuia Salvatore A
CONICET/Faculty of Agricultural Sciences, National University of Lomas de Zamora, 1836 Llavallol, Argentina.
Institute for Agricultural and Forestry Systems in the Mediterranean (ISAFoM), Department of Biology, Agriculture and Food Science (DiSBA), National Research Council (CNR), Via Empedocle, 58, 95128 Catania, Italy.
Plants (Basel). 2020 Sep 18;9(9):1225. doi: 10.3390/plants9091225.
The association among environmental cues, ethylene response, ABA signaling, and reactive oxygen species (ROS) homeostasis in the process of seed dormancy release is nowadays well-established in many species. Alternating temperatures are recognized as one of the main environmental signals determining dormancy release, but their underlying mechanisms are scarcely known. Dry after-ripened wild cardoon achenes germinated poorly at a constant temperature of 20, 15, or 10 °C, whereas germination was stimulated by 80% at alternating temperatures of 20/10 °C. Using an RNA-Seq approach, we identified 23,640 and annotated 14,078 gene transcripts expressed in dry achenes and achenes exposed to constant or alternating temperatures. Transcriptional patterns identified in dry condition included seed reserve and response to dehydration stress genes (i.e., , peroxidases, and ). At a constant temperature, we observed an upregulation of ABA biosynthesis genes (i.e., ), ABA-responsive genes (i.e., and , as well as other genes previously related to physiological dormancy and inhibition of germination. However, the alternating temperatures were associated with the upregulation of ethylene metabolism (i.e., , and ) and signaling (i.e., ) genes and ROS homeostasis regulators genes (i.e., and ). Accordingly, the ethylene production was twice as high at alternating than at constant temperatures. The presence in the germination medium of ethylene or ROS synthesis and signaling inhibitors reduced significantly, but not completely, germination at 20/10 °C. Conversely, the presence of methyl viologen and salicylhydroxamic acid (SHAM), a peroxidase inhibitor, partially increased germination at constant temperature. Taken together, the present study provides the first insights into the gene expression patterns and physiological response associated with dormancy release at alternating temperatures in wild cardoon ( var. ).
如今，在许多物种中，种子休眠解除过程中环境信号、乙烯反应、脱落酸信号传导和活性氧（ROS）稳态之间的关联已得到充分证实。交替温度被认为是决定休眠解除的主要环境信号之一，但其潜在机制却鲜为人知。干燥后熟的野生刺苞菜瘦果在20、15或10℃恒温下萌发较差，而在20/10℃交替温度下萌发率提高了80%。我们采用RNA测序方法，鉴定出23,640个基因转录本，并对干燥瘦果以及暴露于恒温或交替温度下的瘦果中表达的14,078个基因转录本进行了注释。在干燥条件下鉴定出的转录模式包括种子储备以及对脱水胁迫基因（即过氧化物酶等）的反应。在恒温条件下，我们观察到脱落酸生物合成基因（即 ）、脱落酸响应基因（即 和 ）以及其他先前与生理休眠和萌发抑制相关的基因上调。然而，交替温度与乙烯代谢（即 、 和 ）和信号传导（即 ）基因以及ROS稳态调节基因（即 和 ）的上调有关。因此，交替温度下的乙烯产量是恒温下的两倍。乙烯或ROS合成与信号抑制剂存在于萌发培养基中时，显著但未完全降低20/10℃下的萌发率。相反，甲基紫精和过氧化物酶抑制剂水杨羟肟酸（SHAM）的存在在恒温下部分提高了萌发率。综上所述，本研究首次深入了解了野生刺苞菜（ 变种）在交替温度下与休眠解除相关的基因表达模式和生理反应。
