Effect of exogenous GA3 and its inhibitor paclobutrazol on floral formation, endogenous hormones, and flowering-associated genes in 'Fuji' apple (Malus domestica Borkh.).
Gibberellins (GAs) reduce apple (Malus domestica) flowering rates; however, the mechanism of their action is not fully understood. To gain a better insight into gibberellin-regulated flowering, here, 5 year-old 'Fuji' apple trees were used to explore the responses of hormones [GA1+3, GA4+7, indole-3-acetic acid (IAA), zeatin-riboside (ZR), and abscisic acid (ABA)], and gibberellin- and flowering-associated genes, to applications of gibberellin acid (GA3) and paclobutrazol (PAC). Results showed that GA3 relatively stimulated vegetative growth and delayed floral induction. Moreover, GA3 spraying significantly affected contents of all endogenous hormones and all the genes tested in at least one time points: the content of endogenous GAs was increased instantly and that of ZR was reduced at 44 days after fullbloom (DAF), which might constitute an unfavorable factor for flower formation; MdKO (ent-kaurene oxidase gene) and MdGA20ox (GA20 oxidase gene) were significantly repressed by a high level of GAs through the negative feedback regulation of GA; additionally, the MdSPLs (SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE) in this study were all significantly repressed by GA3 but promoted by PAC; the expression of MdFT1/2 (FLOWERING LOCUS T), MdSOC1 (SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1) and MdAP1 (APETALA1) in GA3-treated buds changed in the same way, and they were repressed at 44 DAF. We suppose that GA3 spraying disrupts the balance between ZR and GAs, and inhibits floral induction, probably by suppressing MdSPLs and the floral integrators in flower induction, which ultimately contributed to inhibiting flower formation.
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: zhangsongwen686@163.com.
Songwen
S
Zhang
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: afant@nwsuaf.edu.cn.
Dong
D
Zhang
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: likessd@126.com.
Sheng
S
Fan
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: lishadu1992@163.com.
Lisha
L
Du
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: 15136236336@163.com.
Yawen
Y
Shen
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: xinglibo1986@live.com.
Libo
L
Xing
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: lym19890525@163.com.
Youmei
Y
Li
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: m13659181256@163.com.
Juanjuan
J
Ma
College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China. Electronic address: hanmy@nwsuaf.edu.cn.
Mingyu
M
Han
D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics; D016000:Cluster Analysis; D035264:Flowers / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D005875:Gibberellins / Q000494:pharmacology*; D027845:Malus / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D008954:Models, Biological; D010937:Plant Growth Regulators / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014230:Triazoles / Q000494:pharmacology*
D005875:Gibberellins; D010937:Plant Growth Regulators; D014230:Triazoles; C053370:paclobutrazol
Floral induction; Gene expression; Gibberellin; Malus domestica; Plant hormones