Rootstock Affects Floral Induction in Citrus Engaging the Expression of the FLOWERING LOCUS T (CiFT)

Stefania Bennici,Mario Di Guardo,Stefano La Malfa,Giuseppina Las Casas,Alberto Continella,Elisabetta Nicolosi,Alessandra Gentile,Giuseppe Lana,Gaetano Distefano

doi:10.3390/agriculture11020140

Stefania Bennici, Mario Di Guardo + Show 7 more

Open Access

https://doi.org/10.3390/agriculture11020140

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Journal: Agriculture	Publication Date: Feb 8, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: University of Catania, Hunan Agricultural University

Abstract

In Citrus, flower induction represents the transition from vegetative to reproductive growth. The regulation of flower induction is mainly triggered by exposure to low temperatures and water-deficit stress, which activates the signaling cascade leading to an increased expression of the citrus orthologs of the FLOWERING LOCUS T (CiFT). In this study, the relationship between rootstock and flower induction under Mediterranean field conditions was investigated by monitoring the expression levels of the floral promoter CiFT2 in leaves of the pigmented sweet orange “Tarocco Scirè” grafted onto “C35” citrange and “Swingle” citrumelo rootstocks. The latter two are known to confer, respectively, high and low yield efficiency to the scion. In both rootstock/scion combinations, CiFT2 showed a seasonal expression with a peak during the inductive period in January triggered by cold temperature. The “Tarocco Scirè”/”C35” citrange combination showed the highest expression levels for CiFT2; this increased expression was correlated with yield and a higher number of flowers in the following spring, suggesting a significant effect of rootstocks on flower induction mediated by the overexpression of the CiFT2 gene.

Highlights

Sweet orange is one of the most important fruit crops in the world in terms of both production and harvested area: in 2018, the annual world production was equal to 75,413,374 tons with a corresponding harvested area of 4,469,719 hectares [1]
The effect of rootstock on flower induction was investigated through the assessment of CiFT2 expression in leaves of “Tarocco Scirè” sweet orange grafted onto “C35” citrange and “Swingle” citrumelo, two rootstocks characterized by high and low yield efficiency, respectively
Even though both rootstock/scion combinations showed an increased CiFT2 expression during the inductive period (January 2018), the expression level in TS/C35 was threerefomldaihniegdhreerlathtiavnelTySl/oSwC,(apn-vdatlhueen=b0o.0th2)c(oFmigbuirnea1ti)o.nAs ssihgonwifeicdanant dinifcfreeraesneceininJagneunaeryex2p0r1e8s(wsiiotnh bTeSt/wCe3e5nsthhoewtwinog raoostigstnoicfkic/asncitolyn hcoigmhbeirnCatiiFoTn2s ewxapsreaslssoioonbcsoermvpedariendJuwliyth(pT-vSa/SluCe).= Fco0srio.mg0m4nb)iiFfnaiecanbatdirnoutOnlaysrcythwoitbgiotehhtrehar2eis0sne1pc8TroSi(nn/pdSg-Cvspa,eelwauaskehoinr=les2tg00i.i0ns1t38Me)r(; Jeaiudnyn2iben0)o,1Jttu8hhlaeycase2isxg0epn1sr8itefhi(scFesaiinogetnuxlpyrleerhev1iseg)s.lhiroeenrmelaxeivpnereeldsoslfiooCwniF(ipnT-2b5voaowfltuh1a1es = 0.0E3v)ewnatshoreucgohrdbeodthinroToSt/sCto3c5k(/Fsicgiounrec1o)m. binations showed an increased CiFT2 expression during the inductive period (January 2018), the expression level in TS/C35 was threefold higher than TS/SC (p-value = 0.02) (Figure 1)

Summary

Introduction

Sweet orange is one of the most important fruit crops in the world in terms of both production and harvested area: in 2018, the annual world production was equal to 75,413,374 tons with a corresponding harvested area of 4,469,719 hectares [1]. The Mediterranean countries with the highest production of sweet orange are Spain and Italy with 3.6 and 1.5 million tons, respectively [1]. Several works have indicated that floral induction in citrus occurs independently of the photoperiod [4]. Low temperatures (10–18 ◦C day/5–13 ◦C night) and water-deficit stress are recognized as the main factors involved in the induction of flowering in citrus [4,5,6,7]

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Conclusion