Characterization of polyploidy in the resistance to Venturia inaequalis in susceptible and monogenic resistant Malus x domestica Borkh.

Ilnikar, Kristina (author), Štajner, Nataša (mentor), De Storme, Nico (co-mentor)

Apple (M. x domestica), belonging to Rosaceae family, is the third most important fruit worldwide in terms of production and consumption. During the growing season, apple is infected by Venturia inaequalis, causing apple scab, one of the most destructive disease in apple culture. The main approach for controlling this disease is by multiple fungicide applications, which has resulted in resistance of the fungus to various fungicides. One of the potential alternative strategies with improved resistance to apple scab could be growing polyploid apple cultivars. In several cases, polyploids were recognized as more resistant to different types of stress than their diploid counterparts. The main goal of this thesis is to test the effect of polyploidy on phenotypic resistance and expression of defense-related genes and genes involved in the synthesis of phenolic compounds in di- and tetraploid apple varieties ‘Gala’ (scab-susceptible) and ‘Makali’ (monogenic resistant) during infection with V. inaequalis races 1 and 6. During the inoculation process, chlorosis, necrosis and sporulation were visually evaluated according to Chevalier method, and quantification of the fungal DNA qPCR was performed. The severity of evaluated symptoms and concentration of fungal DNA were on average lower in tetraploid than in diploid variants. For gene expression, RT-qPCR was performed. Polyploidy significantly affected the expression of PR-2(b), MPK4, PAL, NCS, F4R and LR in ‘Gala’ and of PR-1, CERK1, NCS, LR and 4CL in ‘Makali’. CDPK, WRKY29, PR-2(a), F3H and CCoAMT were not affected by ploidy.

• Language: English
• Keywords: Polyploidy, Malus domestica, Venturia inaequalis, apple scab, plant resistance, differential gene expression
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [K. Ilnikar]
• Year: 2020
• PID: 20.500.12556/RUL-118673
• UDC: 634.11:631.527.7:631.524.86:632.4(043.2)
• COBISS.SI-ID: 27186435
• Publication date in RUL: 30.08.2020

Secondary language

• Language: Slovenian
• Title: Karakterizacija poliploidije pri odpornosti proti patogeni glivi Venturia inaequalis v občutljivi in monogensko odporni sorti jablan (Malus × domestica Borkh.)

Abstract

Jablana (M. x domestica), pripadnica družine rožnic (Rosaceae), je tretja najbolj pridelovana in uporabljena sadna vrsta v svetovnem merilu. Tekom rastne sezone jo okužujejo številne bolezni, med drugim tudi gliva Venturia inaequalis, ki povzroča jablanov škrlup, gospodarsko najbolj škodljivo bolezen jablan. Za zatiranje te bolezni se običajno uporabljajo fungicidi, vendar pa je gliva razvila odpornost proti številnim fungicidom. Ena izmed potencialnih rešitev za zmanjšanje obsega kemičnega varstva, poleg izboljšane odpornosti proti škrlupu, bi lahko bilo gojenje poliploidnih kultivarjev jablan. Poliploidne rastline so se v primerjavi z diploidnimi izkazale za bolj odporne proti različnim vrstam stresa. V magistrski nalogi je bil analiziran učinek poliploidije na odpornost proti V. inaequalis rase 1 ter 6 in na ekspresijo obrambnih genov ter genov vključenih v sintezo fenolnih spojin v di- in tetraploidni jablani sorte ‘Gala’ (dovzetna za jablanov škrlup) in ‘Makali’ (monogensko odporna). Med inokulacijo so bile na listih ocenjene kloroza, nekroza in sporulacija po metodi Chevalier, količina glivne DNA je bila določena z metodo qPCR. Delež simptomov in koncentracija glivne DNA sta bila manjša v tetraploidnih genotipih v primerjavi z diploidnimi rastlinami. Ekspresija genov je bila analizirana z metodo RT-qPCR. Poliploidija je statistično značilno vplivala na ekspresijo PR-2(b), MPK4, PAL, NCS, F4R in LR v ‘Gala’ ter PR-1, CERK1, NCS, LR in 4CL v ‘Makali’. Na ekspresijo CDPK, WRKY29, PR-2(a), F3H in CCoAMT ploidija ni imela vpliva.

• Keywords: Poliploidija, Malus domestica, Venturia inaequalis, jablanov škrlup, odpornost rastlin, diferencialno izražanje genov