Transcriptome and Metabolome Analyses Provide Insights into the Stomium Degeneration Mechanism in Lily

Lily (Lilium spp.) is a widely cultivated horticultural crop that has high ornamental and commercial value but also the serious problem of pollen pollution. However, mechanisms of anther dehiscence in lily remain largely unknown. In this study, the morphological characteristics of the stomium zone (SZ) from different developmental stages of ‘Siberia’ lily anthers were investigated. In addition, transcriptomic and metabolomic data were analyzed to identify the differentially expressed genes (DEGs) and secondary metabolites involved in stomium degeneration. According to morphological observations, SZ lysis occurred when flower buds were 6–8 cm in length and was completed in 9 cm. Transcriptomic analysis identified the genes involved in SZ degeneration, including those associated with hormone signal transduction, cell structure, reactive oxygen species (ROS), and transcription factors. A weighted co-expression network showed strong correlations between transcription factors. In addition, TUNEL (TdT-mediated dUTP nick-end labeling) assays showed that programmed cell death was important during anther SZ degeneration. Jasmonates might also have key roles in anther dehiscence by affecting the expression of the genes involved in pectin lysis, water transport, and cysteine protease. Collectively, the results of this study improve our understanding of anther dehiscence in lily and provide a data platform from which the molecular mechanisms of SZ degeneration can be revealed

Disparity in elevational shifts of upper species limits in response to recent climate warming in the Qinling Mountains, North-central China

Examinations of upper elevational distribution limits of tree species can provide indications of how subalpine vegetation responds to the ongoing climate warming. Dynamics and functional mechanisms of elevational treelines are reasonably well understood, while explanations for tree species-specific upper elevational distribution limits below the treeline still remain unclear. In this study, we used a state-of-the-art dendroecological approach to reconstruct long-term changes of species-specific upper elevational distribution limits of different plant functional type (i.e., light-demanding deciduous coniferous larch at treeline, shade-tolerant evergreen coniferous fir and shade-intolerant deciduous broad-leaved birch below treeline) along elevational gradients in the Qinling Mountains of north-central China. Over the past three centuries, all the upper species limits shifted upslope as a response to climate warming. However, the warming-induced upslope migrations showed substantial differences, displaying the maximum upward shift of larch with an average elevation of 24.7 m during the past century, while only a slight advance of the non-treeline tree species. The disparity in elevational advance of upper species limits might be attributable to the presence of interspecific competition, showing that the non-treeline tree species experienced intermediate interspecific competition while the treeline tree species experienced no interspecific competition.Thus, our findings suggested that in addition to climate warming, biotic interaction may contribute much to shaping the species-specific upper limit dynamics. This study not only enhanced mechanistic understanding of long-term species-specific upper elevational distribution limit changes, but also highlighted the jointly effects of rising temperatures and species interactions on subalpine vegetation dynamics. (C) 2019 Elsevier B.V. All rights reserved