CRP – V4-2203 Vrednotenje genotipov in vzgoja družin križanj…

CRP – V4-2203 Vrednotenje genotipov in vzgoja družin križanj za proučevanje odpornosti hmelja Humulus lupulus L. na hudo viroidno zakrnelost hmelja

PREDSTAVITEV PROJEKTA

Hmeljarstvo je v Sloveniji zelo pomembna izvozna kmetijska panoga, slovenska hmeljišča predstavljajo 2-3 % svetovnih površin. Kar 98 % hmeljišč je posajenih s slovenskimi sortami, vzgojenimi na Inštitutu za hmeljarstvo in pivovarstvo Slovenije (IHPS). V zadnjih letih slovensko hmeljarstvo ogroža karantenska bolezen “huda viroidna zakrnelost hmelja”, ki jo povzroča Citrus bark cracking viroid (CBCVd). Med dolgoročnejše rešitve problematike CBCVd na hmelju spada predvsem ciljno žlahtnjenje odpornih in tolerantnih sort.

V procesu žlahtnjenja novih sort je zelo pomembna čim večja diverziteta virov odpornosti. IHPS razpolaga z gensko banko divjih moških in ženskih rastlin ter kolekcijo križancev hmelja iz kontinuiranega programa žlahtnjenje hmelja. Genska banka hmelja je slabo ovrednotena oz. vezano na toleranco na CBCVd, praktično ne proučena. Izvesti je potrebno umetna okuževanja izbranih genotipov ter oceniti njihovo občutljivost na CBCVd.

Projekt bo znatno pripomogel k reševanju problematike hude viroidne zakrnelosti hmelja in predstavlja neposreden prenos raziskovalnega dela v prakso in uresničuje cilj stabilne kmetijske pridelave v Sloveniji. Rezultati projekta bodo dolgoročno pripomogli h konkurenčnosti slovenskega hmeljarstva na globalnem trgu.

Določeni viri odpornosti bodo podlaga za vpis novih sort hmelja, odpornih oz. tolerantnih na CBCVd, ki bodo hkrati tudi tržno zanimive.

Opazovanje tolerance križancev hmelja na CBCVd

ABSTRACT IN ENGLISH

Hop growing is a very important export agricultural sector in Slovenia, with Slovenian hop fields representing 2-3% of the total hop growing area. Up to 98% of hop fields are planted with Slovenian varieties bred at the Slovenian Institute of Hop Research and Brewing (IHPS). However, in recent years, Slovenian hop growing has been threatened by the quarantine severe hop stunt disease, which is caused by Citrus bark cracking viroid (CBCVd). Long-term solutions to the CBCVd problem in hops include targeted breeding of resistant and tolerant varieties. Currently, only 6% of hop fields are planted with CBCVd-tolerant varieties.

When breeding new varieties, it is important to incorporate as much genetic diversity as possible into the breeding programme. IHPS has a gene bank containing wild male and female plants, as well as a collection of hop crosses from its ongoing breeding programme. However, the hop gene bank has not been adequately evaluated in terms of tolerance to CBCVd. Artificial infections of selected genotypes must be carried out to assess their susceptibility to CBCVd.

In our project, we established a spatially isolated hop selection field with 49 planted genotypes to carry out artificial infections and determine the tolerance of genetic resources to CBCVd. In this field, we carried out artificial infections and a phenotypic assessment of the infected plants, confirming the presence of CBCVd using appropriate diagnostic techniques. Among the different hop genetic resources at IHPS, we identified female and male hop plants tolerant to CBCVd. Genotypes with known tolerance to CBCVd were included in the initial targeted crosses. We have bred new crossing families that will form the basis for further genetic and molecular research.

Within the project, we analysed the differential expression of hop genes following infection with the viroids CBCVd, HLVd and HSVd. Using existing transcriptomic data, we identified transcripts with extremely high expression levels in infected plants. Contig_1902 and contig_94445 showed the most promised and could serve as potential biomarkers for the early diagnosis of viroid infections. To confirm these findings experimentally, we conducted pot experiments with three hop varieties (Celeia, Styrian Cardinal and Styrian Wolf) infected with CBCVd. Using the RT-qPCR method, we checked the expression of both transcripts on isolated plant material, but were unable to confirm the results of the bioinformatic analysis indicating strongly increased expression.

We shared our knowledge and results with key stakeholders.

The results of the project will significantly contribute to solving the problem of severe hop stunt disease. The project represents a direct transfer of research work into practice and achieves the goal of stable agricultural production in Slovenia. The results of the project will contribute to the competitiveness of Slovenian hop growing on the global market in the long term.

The identified sources of resistance will form the basis for the registration of new hop varieties resistant or tolerant to CBCVd, which will also be of commercial interest.