Leaf color is one of the most important features for plants used for landscape and ornamental purposes. However, the regulatory mechanism of yellow leaf coloration still remains elusive in many plant species. To understand the complex genetic mechanism of yellow-leaf Forsythia, we first compared the pigment content and leaf anatomical structure of yellow-leaf and green-leaf accessions derived from a hybrid population. The physiological and cytological analyses demonstrated that yellow-leaf progenies were chlorophyll deficient with defected chloroplast structure. With comparative transcriptome analysis, we identified a number of candidate genes differentially expressed between yellow-leaf and green-leaf Forsythia plants. Among these genes, we further screened out two candidates, ChlH (magnesium chelatase Subunit H) and POLGAMMA2 (POLYMERASE GAMMA 2), with consistent relative-expression pattern between different colored plants. To verify the gene function, we performed virus-induced gene silencing assays and observed yellow-leaf phenotype with total chlorophyll content reduced by approximately 66 and 83% in ChlH-silenced and POLGAMMA2-silenced plants, respectively. We also observed defected chloroplast structure in both ChlH-silenced and POLGAMMA2-silenced Forsythia. Transient over-expression of ChlH and POLGAMMA2 led to increased chlorophyll content and restored thylakoid architecture in yellow-leaf Forsythia. With transcriptome sequencing, we detected a number of genes related to chlorophyll biosynthesis and chloroplast development that were responsive to the silencing of ChlH and POLGAMMA2. To summarize, ChlH and POLGAMMA2 are two key genes that possibly related to yellow-leaf coloration in Forsythia through modulating chlorophyll synthesis and chloroplast ultrastructure. Our study provided insights into the molecular aspects of yellow-leaf Forsythia and expanded the knowledge of foliage color regulation in woody ornamental plants.

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Water and steam play very important roles to utilize for heating, cooling, and mass exchange and reaction in refinery production. So application of an appropriate water and steam control system to save water and steam can tremendously reduce production cost. A water and steam control system based on a novel method and architecture is presented in this paper. Its application and capability is validated.Index Terms-utility system, water and steam control system, refinery I. INTRODU CTIONRefineries , chemical , petrochemical and pulp-and-paper plants apply utility systems as a means to do work, to heat, to cool, to refine and process raw materials into final products. The utility systems also serve as general vehicle to safely transport and exchange energy and "work " capacity throughout the plant. Due to the complex, integrated and distributed nature of the utility systems, it is typically challenging to comprehend what is dynamically happening in the systems and to identify and act on opportunities for savings or improvement in a timely manner.