Abstract: Tomato is an ideal model species for fleshy fruit development research. SlYABBY2b regulates the ovary locule number, which is increased by gibberellins, in tomato. However, the relationship between SlYABBY2b and endogenous gibberellin is poorly understood. In this study, SlYABBY2b-overexpressing and RNA interference (RNAi) transgenic tomato plants were used to elucidate the mechanism by which SlYABBY2b regulates the ovary locule number and endogenous gibberellin content in tomato. SlYABBY2b-overexpressing plants showed fewer locules and lower gibberellin content than the control plants. Contrasting results were found in the RNAi lines. Therefore, the SlYABBY2b gene negatively regulates tomato ovary locule number and endogenous gibberellin content. Furthermore, the expression of SlYABBY2b gene was remarkably higher than that of the wild type in the apical shoots of gibberellin-deficient mutants. This showed that the gibberellins can inhibit the expression of SlYABBY2b gene negative regulation. Further study revealed that SlYABBY2b suppressed the expression of SlGA20ox1 and SlGA3ox2, but increased that of SlGA2ox1 and SlGA2ox5 in the apical shoots of SlYABBY2b-overexpressing plants, thereby reducing gibberellin content. Contrasting results were found in the RNAi lines. Our results showed that the SlYABBY2b gene was located on gibberellin signal transduction pathways, fed back regulation of the synthesis of gibberellin, and felt exogenous gibberellin signal to further regulate the formation of tomato locule.

SlYABBY2b基因对番茄果实心室数和内源赤霉 素含量的影响

[1]Asahira T, Hosoki T, Shinya K, 1982. Regulation of low temperature-induced malformation of tomato fruit by plant growth regulators. J Jpn Soc Hort Sci, 50(4):468-474.

[2]Barrero LS, Tanksley SD, 2004. Evaluating the genetic basis of multiple-locule fruit in a broad cross section of tomato cultivars. Theor Appl Genet, 109(3):669-679.

[3]Barrero LS, Cong B, Wu F, et al., 2006. Developmental characterization of the fasciated locus and mapping of Arabidopsis candidate genes involved in the control of floral meristem size and carpel number in tomato. Genome, 49(8):991-1006.

[4]Chakrabarti M, Zhang N, Sauvage C, et al., 2013. A cytochrome P450 regulates a domestication trait in cultivated tomato. Proc Natl Acad Sci USA, 110(42):17125-17130.

[5]Chen JG, Zhou X, Zhang YZ, 1998. Gibberellin-responding and non-responding dwarf mutants in foxtail millet. Plant Growth Reg, 26(1):19-24.

[6]Cong B, Barrero LS, Tanksley SD, 2008. Regulatory change in YABBY-like transcription factor led to evolution of extreme fruit size during tomato domestication. Nat Genet, 40(6):800-804.

[7]Dai M, Zhao Y, Ma Q, et al., 2007. The rice YABBY1 gene is involved in the feedback regulation of gibberellin metabolism. Plant Physiol, 144(1):121-133.

[8]Fernández-Lozano A, Yuste-Lisbona FJ, Pérez-Martín F, et al., 2015. Mutation at the tomato EXCESSIVE NUMBER OF FLORAL ORGANS (ENO) locus impairs floral meristem development, thus promoting an increased number of floral organs and fruit size. Plant Sci, 232:41-48.

[9]Foolad MR, 2007. Genome mapping and molecular breeding of tomato. Int J Plant Genomics, 2007:64358.

[10]Fukazawa J, Sakai T, Ishida S, et al., 2000. REPRESSION OF SHOOT GROWTH, a bZIP transcriptional activator, regulates cell elongation by controlling the level of gibberellins. Plant Cell, 12(6):901-915.

[11]Gazzarrini S, Tsuchiya Y, Lumba S, et al., 2004. The transcription factor FUSCA3 controls developmental timing in Arabidopsis through the hormones gibberellin and abscisic acid. Dev Cell, 7(3):373-385.

[12]Hay A, Kaur H, Phillips A, et al., 2002. The gibberellin pathway mediates KNOTTED1-type homeobox function in plants with different body plans. Curr Biol, 12(18):1557-1565.

[13]Hedden P, Phillips AL, 2000. Gibberellin metabolism: new insights revealed by the genes. Trends Plant Sci, 5(12):523-530.

[14]Hernández-Bautista A, Lobato-Ortiz R, Cruz-Izquierdo S, et al., 2015. Fruit size QTLs affect in a major proportion the yield in tomato. Chilean J Agric Res, 75(4):402-409.

[15]Huang Z, van der Knaap E, 2011. Tomato fruit weight 11.3 maps close to fasciated on the bottom of chromosome 11. Theor Appl Genet, 123(3):465-474.

[16]Huang Z, Houten JV, Gonzalez G, et al., 2013. Genome-wide identification, phylogeny and expression analysis of SUN, OFP and YABBY gene family in tomato. Mol Genet Genomics, 288(3-4):111-129.

[17]Illa-Berenguer E, van Houten J, Huang Z, et al., 2015. Rapid and reliable identification of tomato fruit weight and locule number loci by QTL-seq. Theor Appl Genet, 128(7):1329-1342.

[18]Imai R, Yang YY, Tahar AA, et al., 1996. Cloning and light-regulated expression of two cDNAs for ent-kaurene synthase A from tomato. Pant Cell Physiol, 37:143.

[19]Ishida S, Fukazawa J, Yuasa T, et al., 2004. Involvement of 14-3-3 signaling protein binding in the functional regulation of the transcriptional activator REPRESSION OF SHOOT GROWTH by gibberellins. Plant Cell, 16(10):2641-2651.

[20]Jain M, Kaur N, Tyagi AK, et al., 2006. The auxin-responsive GH3 gene family in rice (Oryza sativa). Funct Integr Genomics, 6(1):36-46.

[21]Kumar R, Khurana A, Sharma AK, 2014. Role of plant hormones and their interplay in development and ripening of fleshy fruits. J Exp Bot, 65(16):4561-4575.

[22]Kumaran MK, Bowman JL, Sundaresan V, 2002. YABBY polarity genes mediate the repression of KNOX homeobox genes in Arabidopsis. Plant Cell, 14(11):2761-2770.

[23]Li H, Qi MF, Sun MH, et al., 2017. Tomato transcription factor SlWUS plays an important role in tomato flower and locule development. Front Plant Sci, 8:457.

[24]Li Y, Li TL, Wang D, 2008. Correlation between endogenous hormones of stem apices and fruit locule numbers in tomatoes during floral bud differentiation stages. Agric Sci China, 7(4):447-454.

[25]Lippman Z, Tanksley SD, 2001. Dissecting the genetic pathway to extreme fruit size in tomato using a cross between the small-fruited wild species Lycopersicon pimpinellifolium and L. esculentum var. Giant Heirloom. Genetics, 158(1):413-422.

[26]Liu S, Li TL, 2012. Regulation effects of exogenous gibberellin acid (GA₃) on the formation of tomato (Solanum lycoperscium) ovary locule and fasciated transcription. Arf J Biotechnol, 11(72):13732-13738.

[27]Magome H, Yamaguchi S, Hanada A, et al., 2004. dwarf and delayed-flowering 1, a novel Arabidopsis mutant deficient in gibberellin biosynthesis because of overexpression of a putative AP2 transcription factor. Plant J, 37(5):720-729.

[28]Muños S, Ranc N, Botton E, et al., 2011. Increase in tomato locule number is controlled by two single-nucleotide polymorphisms located near WUSCHEL. Plant Physiol, 156(4):2244-2254.

[29]Olszewski N, Sun TP, Gubler F, 2002. Gibberellin signaling biosynthesis, catabolism, and response pathways. Plant Cell, 14(Suppl 1):S61-S80.

[30]Pesaresi P, Mizzotti C, Colombo M, et al., 2014. Genetic regulation and structural changes during tomato fruit development and ripening. Front Plant Sci, 5:124.

[31]Rebers M, Kaneta T, Kawaide H, et al., 1999. Regulation of gibberellin biosynthesis genes during flower and early fruit development of tomato. Pant J, 17(3):241-250.

[32]Rodríguez GR, Muños S, Anderson C, et al., 2011. Distribution of SUN, OVATE, LC, and FAS in the tomato germplasm and the relationship to fruit shape diversity. Plant Physiol, 156(1):275-285.

[33]Rosin FM, Hart JK, Horner HT, et al., 2003. Overexpression of a knotted-like homeobox gene of potato alters vegetative development by decreasing gibberellin accumulation. Plant Physiol, 132(1):106-117.

[34]Sakamoto T, Miura K, Itoh H, et al., 2004. An overview of gibberellin metabolism enzyme genes and their related mutants in rice. Plant Physiol, 134(4):1642-1653.

[35]Sawhney V, Greyson R, 1971. Induction of multilocular ovary in tomato by gibberellic acid. J Am Soc Hort Sci, 96(2):196-198.

[36]Sawhney VK, Dabbs DH, 1978. Gibberellic acid induced multilocular fruits in tomato and the role of locule number and seed number in fruit size. Can J Bot, 56(22):2831-2835.

[37]Schoof H, Lenhard M, Haecker A, et al., 2000. The stem cell population of Arabidopsis shoot meristems is maintained by a regulatory loop between the CLAVATA and WUSCHEL genes. Cell, 100(6):635-644.

[38]Serrani JC, Sanjuán R, Ruiz-Rivero O, et al., 2007. Gibberellin regulation of fruit set and growth in tomato. Plant Physiol, 145(1):246-257.

[39]Serrani JC, Ruiz-Rivero O, Fos M, et al., 2008. Auxin-induced fruit-set in tomato is mediated in part by gibberellins. Plant J, 56(6):922-934.

[40]Seymour GB, Østergaard L, Chapman NH, et al., 2013. Fruit development and ripening. Annu Rev Plant Biol, 64(1):219-241.

[41]Sponsel VM, Hedden P, 2010. Gibberellin biosynthesis and inactivation. In: Davies PJ (Ed.), Plant Hormones. Springer, Dordrecht, p.63-94.

[42]Tanksley SD, 2004. The genetic, developmental, and molecular bases of fruit size and shape variation in tomato. Plant Cell, 16(Suppl_1):S181-S189.

[43]Tomer E, Moshkovits H, Rosenfeld K, et al., 1998. Varietal differences in the susceptibility to pointed fruit malformation in tomatoes: histological studies of the ovaries. Sci Hortic, 77(3-4):145-154.

[44]van der Knaap E, Chakrabarti M, Chu YH, et al., 2014. What lies beyond the eye: the molecular mechanisms regulating tomato fruit weight and shape. Front Plant Sci, 5:227.

[45]Wang H, Caruso LV, Downie AB, et al., 2004. The embryo MADS domain protein AGAMOUS-Like 15 directly regulates expression of a gene encoding an enzyme involved in gibberellin metabolism. Plant Cell, 16(5):1206-1219.

[46]Xu C, Liberatore KL, Macalister CA, et al., 2015. A cascade of arabinosyltransferases controls shoot meristem size in tomato. Nat Genet, 47(7):784-792.

[47]Yamaguchi S, 2008. Gibberellin metabolism and its regulation. Annu Rev Plant Biol, 59(1):225-251.

[48]Zheng Z, Zhou X, 1995. A monoclonal antibody recognizing nonderivative 13-hydroxy gibberellins and their glucosides. Acta Bot Sin, 37(10):761-769 (in Chinese).

[49]List of electronic supplementary materials

[50]Table S1 Gibberellin mutants and wild types

[51]Table S2 RT-PCR primers used to amplify gene-specific regions