Peel color is an important factor affecting the appearance and quality of citrus fruits, which directly influences consumer preferences.An unsynchronized ripening phenomenon of peel and flesh widely exists in early-maturing mandarin fruits harvested from Chongqing, the previous study found that 661 nm red LED light irradiation was an effective means to promote the coloration of early mandarin fruit.Based on the transcriptome data of red LED light irradiation-treated fruit, it was found that the transcription factor CcbHLH130 (Ciclev10005233 mg) might play an important role in red LED irradiation-promoted coloration of early-maturing mandarin fruit peel.The CcbHLH130 CDS sequence was cloned from the rind of mandarin fruit in the Chongqing area and characterized for biological information and transcription factors.Results showed that CcbHLH130 was highly homologous to Arabidopsis AtFBH4, and was also localized in the nucleus with transcriptional activation activity, and its promoter region had a light response element, abscisic acid response element, and gibberellin response element.After performing transient transformation of CcbHLH130 in tobacco leaves, the leaves at the site of transient transformation were significantly yellowed on the second day, and the contents of chlorophyll a and abscisic acid chlorophyll b were significantly reduced (P<0.05).After transient overexpression of CcbHLH130 in mandarin fruits, the relative expression level of CcbHLH130 in the peel increased significantly on the first day (P<0.05), the expression levels of chlorophyll degradation-related genes CcNYC1, CcChlase1-2, CcHCAR, and CcRCCR was significantly up-regulated at day 2 after the transient transfer (P<0.05), and an obvious color change was found in the peel on the third day, accompanied by a significantly reduce in the contents of chlorophyll and its metabolites (P<0.05).Taken together, CcbHLH130 may accelerate the color change of mandarin fruits by promoting the degradation of chlorophyll.
[1] RODRIGO M J, ALQUÉZAR B, ALÓS E, et al.Biochemical bases and molecular regulation of pigmentation in the peel of citrus fruit[J].Scientia Horticulturae, 2013,163:46-62.
[2] PORRAS I, BROTONS J M, CONESA A, et al.Influence of temperature and net radiation on the natural degreening process of grapefruit (Citrus paradisi Macf.) cultivars Rio Red and Star Ruby[J].Scientia Horticulturae, 2014,173:45-53.
[3] TAO J, ZHANG S L, AN X M, et al.Effects of light on carotenoid biosynthesis and color formation of citrus fruit peel[J].Ying Yong Sheng Tai Xue Bao, 2003,14(11):1833-1836.
[4] MA G, ZHANG L C, KATO M, et al.Effect of blue and red LED light irradiation on β-cryptoxanthin accumulation in the flavedo of Citrus fruits[J].Journal of Agricultural and Food Chemistry, 2012,60(1):197-201.
[5] GONG J L, YANG H B, XU Y N, et al.Differential regulation of red light- and ethephon-induced degreening in postharvest kumquat fruit[J].Postharvest Biology and Technology, 2023,198:112264.
[6] YUAN Z Y, DENG L L, YIN B F, et al.Effects of blue LED light irradiation on pigment metabolism of ethephon-degreened mandarin fruit[J].Postharvest Biology and Technology, 2017,134:45-54.
[7] LU Y X, SHEN X C, LI Y C, et al.Regulation of chlorophyll and carotenoid metabolism in Citrus fruit[J].Horticultural Plant Journal, 2025,11(3): 951-962.
[8] JIAO Y L, LAU O S, DENG X W.Light-regulated transcriptional networks in higher plants[J].Nature Reviews Genetics, 2007,8(3):217-230.
[9] TOLEDO-ORTIZ G, HUQ E, QUAIL P H.The Arabidopsis basic/helix-loop-helix transcription factor family[J].The Plant Cell, 2003,15(8):1749-1770.
[10] MENKENS A E, SCHINDLER U, CASHMORE A R.The G-box:A ubiquitous regulatory DNA element in plants bound by the GBF family of bZIP proteins[J].Trends in Biochemical Sciences, 1995, 20(12):506-510.
[11] LIU Q, DENG S F, LIU L, et al.The chlorophyll and carotenoid metabolism in postharvest mandarin fruit peels is co-regulated by transcription factor CcbHLH35[J].Postharvest Biology and Technology, 2024,216:113030.
[12] ZHU Z G, CHEN G P, GUO X H, et al.Overexpression of SlPRE2, an atypical bHLH transcription factor, affects plant morphology and fruit pigment accumulation in tomato[J].Scientific Reports, 2017,7:5786.
[13] SANAGI M, AOYAMA S, KUBO A, et al. Low nitrogen conditions accelerate flowering by modulating the phosphorylation state of FLOWERING BHLH 4 in Arabidopsis[J]. Proceedings of the National Academy of Sciences of the United States of America, 2021, 118(19): e2022942118.
[14] ZHAO Q, FAN Z H, QIU L N, et al.MdbHLH130, an apple bHLH transcription factor, confers water stress resistance by regulating stomatal closure and ROS homeostasis in transgenic tobacco[J].Frontiers in Plant Science, 2020,11:543696.
[15] ZHANG Y Q, LIU Z J, CHEN Y D, et al.Phytochrome-interacting factor 5 (PIF5) positively regulates dark-induced senescence and chlorophyll degradation in Arabidopsis[J].Plant Science, 2015,237:57-68.
[16] WANG H L, LIU Q, DENG S F, et al.Transcription factor CcbHLH66 regulates mandarin fruit coloration via modulating the expression of chlorophyll degradation related genes CcRCCR and CcNYC[J].Postharvest Biology and Technology, 2024,218:113188.
[17] 刘倩, 邓淑芳, 刘玲, 等.转录因子CcbHLH107调控蜜橘果实转色的功能分析[J].食品科学, 2024,45(15):194-204.
LIU Q, DENG S F, LIU L, et al.Functional analysis of the transcription factor CcbHLH107 regulating the color change of mandarin fruit[J].Food Science, 2024,45(15):194-204.
[18] LOVE M I, HUBER W, ANDERS S.Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2[J].Genome Biology, 2014,15(12):550.
[19] 张暄, 陈鸥, 王文军, 等.ZjERF098鉴定及其提高冬枣黑斑病抗病性的效果研究[J].食品与发酵工业, 2025, 51(1):55-63.
ZHANG X, CHEN O, WANG W J, et al.Identification of ZjERF098 and investigation of its enhancing effect on winter jujube resistance to black spot rot[J].Food and Fermentation Industries, 2025, 51(1):55-63.
[20] WANG W J, LI T, CHEN J L, et al.A self-regulated transcription factor CsWRKY33 enhances resistance of Citrus fruit to Penicillium digitatum[J].Postharvest Biology and Technology, 2023,198:112267.
[21] GE X X, CAO T T, YI L H, et al.Low and high storage temperature inhibited the coloration of mandarin fruit (Citrus unshiu Marc.) with different mechanism[J].Journal of the Science of Food and Agriculture, 2022, 102(15):6930-6941.
[22] DAS A, GUYER L, HÖRTENSTEINER S. Chlorophyll and Chlorophyll Catabolite Analysis by HPLC[M]. New York, NY: Springer New York, 2018:223-235.
[23] DENG L L, YUAN Z Y, XIE J, et al.Sensitivity to ethephon degreening treatment is altered by blue LED light irradiation in mandarin fruit[J].Journal of Agricultural and Food Chemistry, 2017,65(30):6158-6168.
[24] QUAIL P H.Photosensory perception and signalling in plant cells:New paradigms?[J].Current Opinion in Cell Biology, 2002,14(2):180-188.
[25] LU X D, ZHOU C M, XU P B, et al.Red-light-dependent interaction of phyB with SPA1 promotes COP1-SPA1 dissociation and photomorphogenic development in Arabidopsis[J].Molecular Plant, 2015,8(3):467-478.
[26] LU S W, ZHANG M W, ZHUGE Y X, et al.VvERF17 mediates chlorophyll degradation by transcriptional activation of chlorophyll catabolic genes in grape berry skin[J].Environmental and Experimental Botany, 2022,193:104678.
[27] JIBRAN R, SULLIVAN K L, CROWHURST R, et al.Staying green postharvest:How three mutations in the Arabidopsis chlorophyll b reductase gene NYC1 delay degreening by distinct mechanisms[J].Journal of Experimental Botany, 2015,66(21):6849-6862.
[28] HÖRTENSTEINER S, MATILE P.12 - How Leaves Turn Yellow:Catabolism of Chlorophyll[M].NOODÉN L D.Plant Cell Death Processes.San Diego:Academic Press, 2004:189-202.
[29] AUBRY S, FANKHAUSER N, OVINNIKOV S, et al.Pheophorbide a may regulate jasmonate signaling during dark-induced senescence[J].Plant Physiology, 2020,182(2):776-791.
[30] HARPAZ-SAAD S, AZOULAY T, ARAZI T, et al.Chlorophyllase is a rate-limiting enzyme in chlorophyll catabolism and is posttranslationally regulated[J].The Plant Cell, 2007,19(3):1007-1022.
[31] TIAN S L, YANG Y Y, FANG B, et al.The CrMYB33 transcription factor positively coordinate the regulation of both carotenoid accumulation and chlorophyll degradation in the peel of Citrus fruit[J].Plant Physiology and Biochemistry, 2024,209:108540.
[32] YIN X R, XIE X L, XIA X J, et al.Involvement of an ethylene response factor in chlorophyll degradation during Citrus fruit degreening[J].The Plant Journal, 2016,86(5):403-412.
