Background Phalaenopsis bellina and its closely related species, P. violacea, emit linalool, geraniol and their derivatives as the predominant monoterpenes at the full-bloom stages. Geranyl diphosphate synthase (PbGDPS) is the key enzyme that converts precursors for monoterpene biosynthesis. Besides the monoterpenes being synthesized in concert with floral development stages, we noticed that the scent emission of P. bellina and P. violacea was detected mainly in the daytime.ResultsThe monoterpenes of P. violacea flowers displayed a diurnal emission pattern, which was regulated by an internal oscillator in the treatment of constant light. In contrast, constant dark diminished the scent emission levels, indicating that light also affects monoterpene emission in P. violacea. Further treating P. violacea with various light wavelengths showed that the monoterpene emission was greatest in white light condition. Other Phalaenopsis hybrids, including P. I-Hsin Venus ‘KHM2212’ and P. Meidarland Bellina Age ‘LM128’, responded differently to various light wavelengths but most of them still showed the highest scent emission under the whole spectra of light. A great number of light-responsive, HY5-interacting, and circadian-responsive elements was enriched on the promoters of both structural genes and transcription factors for monoterpene biosynthesis. Furthermore, several putative genes encoding components involved in light and circadian signaling pathways were also identified in the transcriptome of P. bellina flowers at consecutive stages (from the anthesis day to day 7 post anthesis).ConclusionsTaken together, both circadian clock and light factors had positive effects on orchid floral scent emission, and the regulation resided on the control of both structural genes and transcription factors for monoterpene biosynthesis.

Software testing methodologies and metrics are key issues to improve and assure software quality. They are important areas in the research of Software Engineering. However, not many focus on the testing criteria and metrics evaluation of a class hierarchy. This paper introduces an important concept named URI (Unit Repeated Inheritance) to realize integrated object-oriented testing and object-oriented metrics. The approach describes an ILT (Inheritance Level Technique) method as a guide to test object-oriented software errors and measure the software complexity of a class hierarchy. The proposed technique shows that inheritance has a close relation to object-oriented software complexity and reveals that overuse of repeated(multiple) inheritance will increase software complexity and be prone to implicit software errors. Also, two test criteria: intra level first and inter level first are presented.

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