Viral infections in stone fruit crops cause substantial economic losses across all sectors of production. Despite their significance, viruses affecting stone fruits remain under-investigated in Kazakhstan. Among these, plum pox virus (PPV, genus Potyvirus, family Potyviridae), commonly known as Sharka, is the most critical viral pathogen worldwide, severely threatening the sustainable cultivation of stone fruits and posing risks to food security. This study aimed to evaluate virus management strategies in stone fruit crops to facilitate the production of healthy planting material from valuable genotypes. Field surveys were conducted in plum and apricot orchards located in the Almaty region (Southeast Kazakhstan) and the Saryagash region (Southern Kazakhstan). Plant samples were tested for the presence of the following viruses: apple chlorotic leaf spot virus (ACLSV), apple mosaic virus (ApMV), PPV, prune dwarf virus (PDV), prunus necrotic ringspot virus (PNRSV), cherry green ring mottle virus (CGRMV), and myrobalan latent ringspot virus (MLRSV). Real-time RT-PCR diagnostics confirmed the presence of PPV in the ‘Stanley’ and ‘Ansar’ cultivars and Prunus armeniaca genotypes, while both PPV and ACLSV were detected in the ‘Ayana’ variety. Chemotherapy (Ribavirin), thermotherapy, cryotherapy, and shoot apical meristem (SAM) culture, both individually and in combination, were used to eliminate viruses and regenerate virus-free plants. Successful virus eradication was achieved for PPV and ACLSV. However, the ‘Stanley’ and ‘Ansar’ cultivars did not survive the treatment process, likely due to high thermo- or cryo-sensitivity. As a result of this research, an in vitro collection of virus-free plants was established, comprising eight rootstocks, six plum cultivars, and three apricot genotypes.

K.R. AISAKULOVA, N.D. SLYAMOVA, A.M. USTEMIROVA, A.A. SEISENOVA, S.ZH. KAZYBAYEVA, S. SKAK, and ZH. MATAI Citation: Aisakulova KR, Slyamova ND, Ustemirova AM, Seisenova AA, Kazybayeva SZh, Skak S, Matai Zh (2023). Organic fertilizer’s role in the improvement of soil microflora and biometric values in fruit crops. SABRAO J. Breed. Genet.

In the present study, the most valuable cultivar ‘Aport krovavo-krasnyy’ was grafted onto M. sieversii genotypes harvested from 11 populations in Dzungarian Alatau and Ile Alatau to identify ones resistant to Erwinia amylovora. The wild apple populations included in the present research have not been previously explored. Seedling population 10, developed using rootstocks from a M. sieversii population growing in Turgen, demonstrated the highest resistance to Erwinia amylovora, showing no fire blight symptoms and no positive PCR results for E. amylovora during the eight years of monitoring in the Talgar field (Kazakhstan) from 2015 to 2022. The population from Steep Tract (seedling population 1) was also valuable for breeding and reduced the pathogen distribution to below 30%. Genotypes from a genetic reserve (seedling population 5) were the most susceptible among the researched populations, with a disease distribution level of 24–95%. In seedling population 5, trees affected at least twice by the pathogen exhibited wilting, shepherd’s crook formation, leaf necrosis, and occasional exudate droplets, while trees in other combinations primarily showed shoot wilting and leaf death. Fire blight disease also developed more rapidly within the plant in seedling population 5; by 2020, one tree nearly died after only two infections.

Apple (Malus domestica Borkh.) is an economically important fruit crop in Kazakhstan, where its wild progenitor, Malus sieversii, represents a valuable source of genetic diversity and disease resistance. Apple scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha) are among the most destructive fungal diseases limiting apple production. This study aimed to identify resistant M. sieversii rootstocks using integrated phytopathological and molecular analyses of graft combinations with the cultivar ‘Aport’. Field evaluations conducted during 2023–2025 revealed considerable variation in disease resistance among 11 scion–rootstock combinations. Forms №4, №7, №9, and №10 remained free of symptoms of both diseases throughout the study period, whereas forms №3, №5, and №8 exhibited moderate susceptibility to apple scab. The PCR screening identified scab resistance loci Rvi6 (forms №2, №3, №7, and №10), Rvi2/Rvi8 (№8, №9, and №10), Rvi5 (№7 and №10), and Rvi14 (№2, №7, and №10). Powdery mildew resistance was associated with the Pl1 locus, which was detected in all analyzed forms, while Pl2 was identified only in forms №2 and №10, and Pl-w in forms №3, №10, and №18. Form №10 exhibited the most favuorable genetic profile, combining multiple scab and powdery mildew resistance loci with complete field resistance. The results demonstrate the effectiveness of integrating molecular markers with field assessment for identifying resistant apple germplasm and highlight promising donor genotypes for breeding disease-resistant cultivars adapted to Kazakhstan.