Youzhen Hu, Bin Liu, Huazhong Ren, Liping Chen, Christopher B. Watkins and Su-Sheng Gan✉

Core

Cytokinins retard leaf senescence and must be degraded at the onset of and during leaf senescence. A mechanism is revealed, in which the senescence-specific transcription factor, AtNAP, physically binds to the promoter of AtCKX3 to activate cytokinin oxidase expression and catabolizing cytokinins and thereby facilitating senescence processes.

Xin Wang, Kaori Ando, Shan Wu, Umesh K. Reddy, Prabin Tamang, Kan Bao, Sue A. Hammar, Rebecca Grumet, James D. McCreight✉ and Zhangjun Fei✉

Core

Genetic characterization of 2083 melon accessions in the U.S. National Plant Germplasm System provides insights into melon genetic diversity, origin and domestication, and facilitates the construction of a melon core collection that captures the majority of the genetic variation in the germplasm. Genome-wide association studies identified potentially associated genome regions related to fruit quality and other horticultural traits, providing valuable information for melon research and breeding.

Yu-Tong Jiang, Lu-Han Yang, Ali Ferjani and Wen-Hui Lin✉

Abstract

Vacuoles are organelles in plant cells that play pivotal roles in growth and developmental regulation. The main functions of vacuoles include maintaining cell acidity and turgor pressure, regulating the storage and transport of substances, controlling the transport and localization of key proteins through the endocytic and lysosomal-vacuolar transport pathways, and responding to biotic and abiotic stresses. Further, proteins localized either in the tonoplast (vacuolar membrane) or inside the vacuole lumen are critical for fruit quality. In this review, we summarize and discuss some of the emerging functions and regulatory mechanisms associated with plant vacuoles, including vacuole biogenesis, vacuole functions in plant growth and development, fruit quality, and plant-microbe interaction, as well as some innovative research technology that has driven advances in the field. Together, the functions of plant vacuoles are important for plant growth and fruit quality. The investigation of vacuole functions in plants is of great scientific significance and has potential applications in agriculture.

Yongfeng Guo, Guodong Ren, Kewei Zhang, Zhonghai Li, Ying Miao✉ and Hongwei Guo✉

Abstract

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 of senescence-associated genes (SAGs) via reverse genetic research in model plant Arabidopsis thaliana as 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.

Yuying Wang, Peiwen Wang, Weihao Wang, Lingxi Kong, Shiping Tian and Guozheng Qin✉

Core

The transcription factor SlDof1 is required for normal fruit ripening in tomato. Knockdown of SlDof1 expression delays ripening-related processes, and transcriptome analysis coupled with ChIP-seq shows that some well-known ripening-related genes are direct targets of SlDof1. Our study demonstrates SlDof1’s regulatory function and provides insights about the molecular regulatory networks controlling fruit ripening.