In Vitro Collection for the Safe Storage of Grapevine Hybrids and Identification of the Presence of Plasmopara viticola Resistance Genes.

This paper focuses on the creation of an in vitro collection of grapevine hybrids from the breeding program of the Kazakh Scientific Research Institute of Fruit Growing and Viticulture and investigates the presence of Plasmopara viticola resistance mediated by Rpv3 and Rpv12 loci. We looked at the optimization of in vitro establishment using either shoots taken directly from field-grown plants or from budwood cuttings forced indoors. We further screened for the presence of endophyte contamination in the initiated explants and optimized the multiplication stage. Finally, the presence of the resistance loci against P. viticola was studied. The shoots initiated from the field-sourced explants were the more effective method of providing plant sources for in vitro initiation once all plant accessions met the goal of in vitro establishment. The concentration of phytohormones and the acidity of the culture medium have a great effect on the multiplication rate and the quality of in vitro stock cultures. Out of 17 grapevine accessions, 16 showed the presence of single or combined resistance loci against P. viticola. The grapevine accessions identified as carrying Rpv3 and Rpv12 alleles represent important genetic resources for disease resistance breeding programs. These accessions may further contribute to the creation of new elite cultivars of economic interest.

Application of Biotechniques for In Vitro Virus and Viroid Elimination in Pome Fruit Crops.

Sustainable production of pome fruit crops is dependent upon having virus-free planting materials. The production and distribution of plants derived from virus- and viroid-negative sources is necessary not only to control pome fruit viral diseases but also for sustainable breeding activities, as well as the safe movement of plant materials across borders. With variable success rates, different in vitro-based techniques, including shoot tip culture, micrografting, thermotherapy, chemotherapy, and shoot tip cryotherapy, have been employed to eliminate viruses from pome fruits. Higher pathogen eradication efficiencies have been achieved by combining two or more of these techniques. An accurate diagnosis that confirms complete viral elimination is crucial for developing effective management strategies. In recent years, considerable efforts have resulted in new reliable and efficient virus detection methods. This comprehensive review documents the development and recent advances in biotechnological methods that produce healthy pome fruit plants. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Effect of Plant Preservative MixtureTM on Endophytic Bacteria Eradication from In Vitro-Grown Apple Shoots.

Endophytic contaminants are a common problem for the in vitro propagation of woody plants and have significant economic repercussions for the conservation of plant genetic resources and commercial micropropagation. In this study, first, the microbial contamination that appeared around the base of in vitro-grown apple shoots was identified as Bacillus megaterium. Then, plant preservative mixture (PPMTM) was used as a bactericidal agent in plant tissue culture. Its efficacy for eradicating endophytic B. megaterium in in vitro cultures of apple was tested. In vitro-contaminated shoots were grown in tissue culture medium supplemented with 0.2% v/v PPMTM for 12 weeks and then transferred to medium without any PPMTM and cultured for 24 weeks. This study showed that PPMTM is an effective agent for controlling the growth of B. megaterium. Our results highlight the species-specific response of apple shoots to PPMTM. PPMTM was effective in controlling endogenous microbial contaminations from apple varieties 'Golden Delicious', 'Landsberger Renette', 'Suislepper', and 'Aport krovavo-krasnyi'; meanwhile, in 'KG 7' and 'Gold Rush', all the plants grown in the absence of PPMTM were still bacterially contaminated, even though they were pre-treated for 12 weeks in PPMTM-supplemented medium. These results therefore suggest the essentiality of further testing of extended incubation of PPMTM in these cultivars that had outbreaks of bacterial contamination.

Eradication of Potato Virus S, Potato Virus A, and Potato Virus M From Infected in vitro-Grown Potato Shoots Using in vitro Therapies.

Certain viruses dramatically affect yield and quality of potatoes and have proved difficult to eradicate with current approaches. Here, we describe a reliable and efficient virus eradication method that is high throughput and more efficacious at producing virus-free potato plants than current reported methods. Thermotherapy, chemotherapy, and cryotherapy treatments were tested alone and in combination for ability to eradicate single and mixed Potato virus S (PVS), Potato virus A (PVA), and Potato virus M (PVM) infections from three potato cultivars. Chemotherapy treatments were undertaken on in vitro shoot segments for four weeks in culture medium supplemented with 100 mg L-1 ribavirin. Thermotherapy on in vitro shoot segments was applied for two weeks at 40°C (day) and 28°C (night) with a 16 h photoperiod. Plant vitrification solution 2 (PVS2) and cryotherapy treatments included a shoot tip preculture followed by exposure to PVS2 either without or with liquid nitrogen (LN, cryotherapy) treatment. The virus status of control and recovered plants following therapies was assessed in post-regeneration culture after 3 months and then retested in plants after they had been growing in a greenhouse for a further 3 months. Microtuber production was investigated using in vitro virus-free and virus-infected segments. We found that thermotherapy and cryotherapy (60 min PVS2 + LN) used alone were not effective in virus eradication, while chemotherapy was better but with variable efficacy (20-100%). The most effective result (70-100% virus eradication) was obtained by combining chemotherapy with cryotherapy, or by consecutive chemotherapy, combined chemotherapy and thermotherapy, then cryotherapy treatments irrespective of cultivar. Regrowth following the two best virus eradication treatments was similar ranging from 8.6 to 29% across the three cultivars. The importance of virus removal on yield was reflected in "Dunluce" free of PVS having higher numbers of microtubers and in "V500' free of PVS and PVA having a greater proportion of microtubers > 5 mm. Our improved procedure has potential for producing virus-free planting material for the potato industry. It could also underpin the global exchange of virus-free germplasm for conservation and breeding programs.

Thermotherapy Followed by Shoot Tip Cryotherapy Eradicates Latent Viruses and Apple Hammerhead Viroid from In Vitro Apple Rootstocks.

Virus and viroid-free apple rootstocks are necessary for large-scale nursery propagation of apple (Malus domestica) trees. Apple stem grooving virus (ASGV) and Apple chlorotic leaf spot virus (ACLSV) are among the most serious apple viruses that are prevalent in most apple growing regions. In addition to these viruses, a new infectious agent named Apple hammerhead viroid (AHVd) has been identified. We investigated whether thermotherapy or cryotherapy alone or a combination of both could effectively eradicate ACLSV, ASGV, and AHVd from in vitro cultures of four apple rootstocks developed in the Cornell-Geneva apple rootstock breeding program (CG 2034, CG 4213, CG 5257, and CG 6006). For thermotherapy treatments, in vitro plants were treated for four weeks at 36 °C (day) and 32 °C (night). Plant vitrification solution 2 (PVS2) and cryotherapy treatments included a shoot tip preculture in 2 M glycerol + 0.8 M sucrose for one day followed by exposure to PVS2 for 60 or 75 min at 22 °C, either without or with liquid nitrogen (LN, cryotherapy) exposure. Combinations of thermotherapy and PVS2/cryotherapy treatments were also performed. Following treatments, shoot tips were warmed, recovered on growth medium, transferred to the greenhouse, grown, placed in dormancy inducing conditions, and then grown again prior to sampling leaves for the presence of viruses and viroids. Overall, thermotherapy combined with cryotherapy treatment resulted in the highest percentage of virus- and viroid-free plants, suggesting great potential for producing virus- and viroid-free planting materials for the apple industry. Furthermore, it could also be a valuable tool to support the global exchange of apple germplasm.

Grapevine Shoot Tip Cryopreservation and Cryotherapy: Secure Storage of Disease-Free Plants.

Grapevine (Vitis spp.) is one of the most economically important temperate fruit crops. Grapevine breeding programs require access to high-quality Vitis cultivars and wild species, which may be maintained within genebanks. Shoot tip cryopreservation is a valuable technique for the safe, long-term conservation of Vitis genetic resources that complements traditional field and in vitro germplasm collections. Vitis is highly susceptible to virus infections. Virus-free plants are required as propagation material for clonally propagated germplasm, and also for the global exchange of grapevine genetic resources. Shoot tip cryotherapy, a method based on cryopreservation, has proven to be effective in eradicating viruses from infected plants, including grapevine. This comprehensive review outlines/documents the advances in Vitis shoot tip cryopreservation and cryotherapy that have resulted in healthy plants with high regrowth levels across diverse Vitis species.

Cryotherapy by encapsulation-dehydration is effective for in vitro eradication of latent viruses from 'Marubakaido' apple rootstock.

Apple stem pitting virus (ASPV), Apple chlorotic leaf spot virus (ACLSV) and Apple stem grooving virus (ASGV) are several major viral pathogens of apple trees, responsible for substantial damage to the world's apple industry. This study aimed to evaluate the effectiveness of the encapsulation-dehydration cryopreservation technique to eradicate these viral pathogens from in vitro shoot tips excised from 'Marubakaido' apple rootstock cultures. Axillary shoot tips were excised from in vitro cultures, encapsulated in alginate beads, precultured in MS salts, dehydrated in a laminar flow hood, immersed in liquid nitrogen, then warmed and recovered on medium. After LN exposure, in vitro rooting and acclimatization, recovered 'Marubakaido' plants exhibited 52% survival and 35% regrowth without callus formation. After 8 months of regrowth, PCR analyses revealed that all the plants were free of ACLSV and ASPV, but 2 out of 20 recovered plants were still infected with ASGV. This is the first report in Brazil of the application of cryotherapy to eradicate viral complexes in Malus. Cryotherapy can facilitate the production of virus-free plants by producing high quality plant material.

Winter cover crops affecting physical and chemical soil attributes in a commercial vineyard / Plantas de cobertura de inverno afetando atributos químicos e físicos do solo em vinhedo comercial

ABSTRACT: Cover crops may have direct or indirect effects on the physical and chemicalsoil attributes; these cropsplay a key role in the cycling of nutrients in the soil and add labile organic carbon, bringing economic and environmental benefits to the system. To study the effect of cover crops on the physical and chemical properties of an Oxisol, a three-year experiment was conducted in a commercial vineyard located at Epagri's Experimental Station in Videira, SC, Brazil. Different winter species (white clover, red clover, common vetch, turnip, corn spurrey, black oat, rye, and ryegrass) were sown in addition to treatments with manual weeding or mechanical mowing. Certain chemical and physical attributes of soil were determined in samples collected fromlayers 0-0.1 and 0.1-0.2m deep on the vinerows and between rows, as well as the dry mass of winter cover crops. Few chemical and physical attributes of the soil changed among winter cover crops and did not differ from the crops managed with mechanical mowing or hand weeding of spontaneous vegetation. Vine rows provided more adequate values of most physical and chemical soil attributes.

ESUMO: As plantas de cobertura podem apresentar efeitos diretos ou indiretos sobre os atributos físicos e químicos do solo, desempenhando papel fundamental na ciclagem dos nutrientes e na adição de carbono orgânico lábil ao solo, trazendo benefícios econômicos e ecológicos ao sistema. Para estudar o efeito de plantas de cobertura sobre os atributos físicos e químicos de um Nitossolo Vermelho, foi conduzido por três anos um experimento com semeadura de diferentes espécies de inverno (trevo-branco, trevo-vermelho, ervilhaca-comum, nabo-forrageiro, espérgula, aveia-preta, centeio e azevém), além dos tratamentos com capina manual e roçada mecânica, em um vinhedo comercial localizado na Estação Experimental da Epagri em Videira, SC. Foram determinados alguns atributos químicos e físicos do solo em amostras coletadas nas camadas de 0-0,1 e 0,1-0,2m de profundidade na linha e na entrelinha da cultura, além da massa seca das plantas de cobertura de inverno. As plantas de cobertura do solo alteram poucos atributos químicos e físicos do solo e não se diferenciam do manejo da vegetação espontânea com capinas manuais ou com roçadas mecânicas. A linha da cultura apresenta valores mais adequados da maioria dos atributos físicos e químicos do solo.