Leaf senescence, the last stage of leaf development, is a type of postmitotic senescence and is characterized by the functional transition from nutrient assimilation to nutrient remobilization which is essential for plants’ fitness. The initiation and progression of leaf senescence are regulated by a variety of internal and external factors such as age, phytohormones, and environmental stresses. Significant breakthroughs in dissecting the molecular mechanisms underpinning leaf senescence have benefited from the identification of senescence-altered mutants through forward genetic screening and functional assessment of hundreds ofsenescence-associated genes(SAGs)viareverse genetic research in model plantArabidopsis thalianaas well as in crop plants. Leaf senescence involves highly complex genetic programs that are tightly tuned by multiple layers of regulation, including chromatin and transcription regulation, post-transcriptional, translational and post-translational regulation. Due to the significant impact of leaf senescence on photosynthesis, nutrient remobilization, stress responses, and productivity, much effort has been made in devising strategies based on known senescence regulatory mechanisms to manipulate the initiation and progression of leaf senescence, aiming for higher yield, better quality, or improved horticultural performance in crop plants. This review aims to provide an overview of leaf senescence and discuss recent advances in multi-dimensional regulation of leaf senescence from genetic and molecular network perspectives. We also put forward the key issues that need to be addressed, including the nature of leaf age, functional stay-green trait, coordination between different regulatory pathways, source-sink relationship and nutrient remobilization, as well as translational researches on leaf senescence.

Leaf senescence in plants involves both positive and negative transcriptional regulation. In this work, we show evidence for the single-stranded DNA-binding protein WHIRLY1 (WHY1) that functions as an upstream suppressor of WRKY53 in a developmental stage-dependent manner during leaf senescence in Arabidopsis (Arabidopsis thaliana). The why1 mutant displayed an early-senescence phenotype. In this background, the expression levels of both WRKY53 and the senescence-associated protease gene SAG12 increased. WHY1 bound to the sequence region that contains an elicitor response element motif-like sequence, GNNNAAATT, plus an AT-rich telomeric repeat-like sequence in the WRKY53 promoter in in vivo and in vitro mutagenesis assays as well as in a chromatin immunoprecipitation assay. This binding to the promoter of WRKY53 was regulated in a developmental stage-dependent manner, as verified by chromatin immunoprecipitation-polymerase chain reaction assay. This direct interaction was further determined by a transient expression assay in which WHY1 repressed β-GLUCURONIDASE gene expression driven by the WRKY53 promoter. Genetic analysis of double mutant transgenic plants revealed that WHY1 overexpression in the wrky53 mutant (oeWHY1wrky53) had no effect on the stay-green phenotype of the wrky53 mutant, while a WHY1 knockout mutant in the wrky53 mutant background (why1wrky53) generated subtle change in the leaf yellow/green phenotype. These results suggest that WHY1 was an upstream regulator of WRKY53 during leaf senescence.

A link between the scent and color of Narcissus tazetta flowers can be anticipated due to their biochemical origin, as well as their similar biological role. Despite the obvious aesthetic and ecological significance of these colorful and fragrant components of the flowers and the molecular profiles of their pigments, fragrant formation has addressed in some cases. However, the regulatory mechanism of the correlation of fragrant components and color patterns is less clear. We simultaneously used one way to address how floral color and fragrant formation in different tissues are generated during the development of an individual plant by transcriptome-based weighted gene co-expression network analysis (WGCNA). A spatiotemporal pattern variation of flavonols/carotenoids/chlorophyll pigmentation and benzenoid/phenylpropanoid/ monoterpene fragrant components between the tepal and corona in the flower tissues of Narcissus tazetta, was exhibited. Several candidate transcription factors: MYB12, MYB1, AP2-ERF, bZIP, NAC, MYB, C2C2, C2H2 and GRAS are shown to be associated with metabolite flux, the phenylpropanoid pathway to the production of flavonols/anthocyanin, as well as related to one branch of the phenylpropanoid pathway to the benzenoid/phenylpropanoid component in the tepal and the metabolite flux between the monoterpene and carotenoids biosynthesis pathway in coronas. It indicates that potential competition exists between floral pigment and floral fragrance during Narcissus tazetta individual plant development and evolutionary development.

Triple-localized WHIRLY2 plays a vital role in carbon reallocation from maternal tissue to filial tissue through controlling sucrose transporter gene expression

Arabidopsis nuclear- and chloroplast-localized WHIRLY1 adjusts SA content in cells via ICS1, PAL1, and BSMT1 to regulate plant senescence in a developmental-dep