title: Comparative transcriptome profiling of potassium starvation responsiveness in two contrasting watermelon genotypes.
abstract: Potassium (K) is one of the essential nutrients for crops, and K⁺ deficiency highly restricts crop yield and quality. Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] is an economically important crop that often suffers from K⁺ deficiency. To elucidate the underlying tolerance mechanism of watermelon to K⁺ deficiency and to improve K efficiency of watermelon and other crops in the future, two watermelon genotypes, namely, YS and 8424, that exhibit contrasting K efficiencies were studied to compare their response mechanisms to K⁺ deficiency. YS was more tolerant of K⁺ deficiency and displayed less inhibited root growth than 8424. Roots of YS and 8424 seedlings with or without K⁺ supply were harvested at 6 and 120 h after treatment (HAT), and their transcriptomes were analyzed by Illumina RNA sequencing. Different regulation mechanisms of the root K⁺-uptake genes for short- and long-term stress were observed. Genes involved in jasmonic acid and reactive oxygen species production; Ca²⁺ and receptor-like kinase signaling; lignin biosynthesis; and other stress-related genes were repressed in YS, whereas a large number of such stress-related genes were induced in 8424 at 120 HAT. These results suggested that repressed defense and stress response can save energy for better root growth in YS, which can facilitate K⁺ uptake and increase K efficiency and tolerance to K⁺ deficiency. This study presents the first global root transcriptome in watermelon and provides new insights into the molecular mechanisms underlying tolerance to K⁺ deficiency of K-efficient watermelon genotypes.
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education/College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
authors.forename: Molin
authors.initials: M
authors.lastname: Fan
authors.forename: Yuan
authors.initials: Y
authors.lastname: Huang
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Zhong
authors.forename: Qiusheng
authors.initials: Q
authors.lastname: Kong
authors.forename: Junjun
authors.initials: J
authors.lastname: Xie
authors.forename: Mengliang
authors.initials: M
authors.lastname: Niu
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
authors.forename: Zhilong
authors.initials: Z
authors.lastname: Bie
mesh_terms: D018533:Biomass; D002412:Cations / Q000032:analysis / Q000378:metabolism; D029773:Citrullus / Q000145:classification / Q000235:genetics* / Q000502:physiology; D015536:Down-Regulation; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D026901:Membrane Transport Proteins / Q000235:genetics*; D008954:Models, Biological; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics; D018517:Plant Roots / Q000235:genetics* / Q000502:physiology; D011188:Potassium / Q000032:analysis / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics; D017423:Sequence Analysis, RNA; D013312:Stress, Physiological; D059467:Transcriptome; D015854:Up-Regulation
chemical_list: D002412:Cations; D026901:Membrane Transport Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D024661:Potassium Channels, Inwardly Rectifying; D011188:Potassium