Comprehensive insights on how 2,4-dichlorophenoxyacetic acid retards senescence in post-harvest citrus fruits using transcriptomic and proteomic approaches.
Auxin-like 2,4-dichlorophenoxyacetic acid (2,4-D), a high-efficiency anti-stalling agent for the post-harvest fresh fruit industry, has had its use restricted due to environmental concerns. However, no other substitutes for 2,4-D are available to the post-harvest industry. Insights into the molecular mechanism underlying the effects of 2,4-D on fruit quality preservation will provide a theoretical basis for exploring new safe and effective anti-stalling agents. This study comprehensively analysed changes in the peel of Olinda Valencia orange [Citrus sinensis (L.) Osbeck] induced by 500 ppm 2,4-D using 'omic'-driven approaches. Transcriptional profiling revealed that transcriptional factor (mainly AP2/ERF, WRKY, and NAC family members), transport, and hormone metabolism genes were over-represented and up-regulated within 24h post-treatment (HPT). Stress defence genes were up-regulated, while cell wall metabolism genes were down-regulated after 48 HPT. However, secondary metabolism genes, especially phenylpropanoid and lignin biosynthesis-related genes, were over-represented at all the time points. Comparative proteomic analysis indicated that the expression of proteins implicated in stress responses (25%), hormone metabolism, and signal transduction (12%) significantly accumulated at the post-transcriptional level. Hormone levels detected by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) showed that abscisic acid, salicylic acid, and 2,4-D significantly increased, while ethylene production (detected by gas chromatography) decreased after 2,4-D treatment. In addition, lignin and water content in the fruit peel also increased and the epicuticle wax ultrastructure was modified. In conclusion, 2,4-D retarded fruit senescence by altering the levels of many endogenous hormones and by improving stress defence capabilities by up-regulating defence-related genes and proteins.
Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan 430070, PR China.
Qiaoli
Q
Ma
Yuduan
Y
Ding
Jiwei
J
Chang
Xiaohua
X
Sun
Li
L
Zhang
Qingjiang
Q
Wei
Yunjiang
Y
Cheng
Lingling
L
Chen
Juan
J
Xu
Xiuxin
X
Deng
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology*; D000040:Abscisic Acid / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002957:Citrus / Q000187:drug effects / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D032084:Citrus sinensis / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D015180:Electrophoresis, Gel, Two-Dimensional; D005030:Ethylenes / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D008031:Lignin / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D020156:Salicylic Acid / Q000378:metabolism; D013312:Stress, Physiological; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D015854:Up-Regulation; D014867:Water / Q000378:metabolism
D005030:Ethylenes; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014867:Water; D015084:2,4-Dichlorophenoxyacetic Acid; D000040:Abscisic Acid; D008031:Lignin; C036216:ethylene; D020156:Salicylic Acid
2,4-dichlorophenoxy acetic acid (2,4-D); ABA; auxin; citrus fruit; ethylene; fruit quality preservation; fruit senescence; plant hormones; stress defence.