Identification of Apple Varieties Resistant to Fire Blight (<i>Erwinia amylovora</i>) Using Molecular Markers

Fire blight of fruit crops is one of the most dangerous diseases for apple trees and other plants of the Rosaceae family, and in Kazakhstan, it is subject to quarantine. To study the spread of fire blight, a phytopathological evaluation of 59 apple varieties of domestic and foreign breeds was carried out in various regions of the south and southeast of Kazakhstan while also considering climatic conditions. The susceptibility of an apple tree to fire blight is influenced by the climatic conditions prevailing in a particular fruit region of Kazakhstan. Samples were collected from various varieties of apple trees with fire blight symptoms for molecular genetic analysis. The phytopathological evaluation and results of the PCR analysis made it possible to identify the causative agent of the disease and its spread to apple varieties in the main fruit regions of Kazakhstan. A molecular study of the resistance to the fire blight pathogen was carried out using the most effective molecular markers. A set of 10 (FBE-1_Y320; FBE-2_Y192; FBE-2_Y495; FBE-2_Y551; FB-MR5-K35; FB-MRS-R240; FB-MR5-R249; FB-MR5-rp16k15_M106; RLP1a; and RLP1b) SNPs was selected, including SNPs reported to be associated with three trait loci, as well as the two markers AE10-375 and GE-8019. Interestingly, the SNP analysis revealed that for all ten markers linked to fire blight resistance, the genotypes of all 59 apple cultivars were identical. No differences in the presence or absence of these markers were observed among the studied varieties. The 26 apple varieties of domestic and foreign breeds most resistant to fire blight were identified in the molecular analysis using the markers AE-375 and GE-8019. Among the studied 59 apple varieties, 23 varieties were identified using the AE-375 marker and 7 varieties with the GE-8019 marker. Samuret, Honeycrisp, Pinova, and Red Topaz were found to be resistant using markers AE-375 and GE-8019. The most promising apple varieties for further breeding for resistance to fire blight programs were selected

Mulching to improve sweet potato production

Sweet potato ((Ipomoea batatas L.) is a high-yielding nutritious specialty crop. There is a growing need for proactive information on sustainable production of sweet potatoes under short growing seasons. The objective of our study was to evaluate the effects of crop residue and synthetic mulches on the growth, yield, and quality parameters of three varieties of sweet potatoes. Three types of mulch, wheat straw (straw), white polyethylene film (white mulch), and black plastic film (black mulch), and a control (no mulch) were evaluated during the 2021 and 2022 growing seasons in the south-eastern region of Kazakhstan. The vine length, meristem number, tuber per plant, and tuber weight were significantly higher under white mulch and black mulch than under straw, and the results were significantly different from the control. The total yields of sweet potato tubers under white mulch and black mulch also varied significantly among the varieties, ranging from 20.5 t/ha for Rizi 0603 to 54.5 t/ha for Xushu 25. The results of the present study will be used to develop other technological sequences for the cultivation of sweet potatoes in the south-eastern region of Kazakhstan. More research is needed to ascertain the stability of the effects of varieties, mulch treatment, and their interactions on yields and to determine other treatments and varieties with better potential to improve sweet potato yields for cultivation in Kazakhstan

Screening of Apple Cultivars for Scab Resistance in Kazakhstan

Scab, caused by Venturia inaequalis, is the most destructive fungal disease of apple worldwide. Apple scab incidence was studied in apple orchards in the south and southeast of Kazakhstan, including the Almaty, Zhambyl, and Turkestan regions, during 2022 and 2023. Disease incidence was higher in the Zhambyl region than in the Turkestan and Almaty regions in both years. The field evaluation suggested that 19 genotypes showed resistance to apple scab. Molecular screening was carried out using eight gene-specific molecular markers (AM19, CH05e03, OPL19, Hi07f02, AL07, K08, HB09, and CH02f06). The results of the molecular screening revealed that in 38 of the 45 studied cultivars, which included 11 Kazakh cultivars and 34 foreign cultivars, the Rvi (Rvi2, Rvi4, Rvi5, Rvi6, Rvi8, Rvi9, Rvi11, Rvi14, and Rvi15) resistance genes were amplified. Resistance genes such as Rvi2, Rvi4, Rvi6, and Rvi9 are still useful for breeding, but their use is recommended only in extended pyramids of multiple resistance genes. Several cultivars will be strong candidates for further breeding programs against apple scab and for the pyramiding of scab resistance genes in new cultivars

Genetic structure and genome-wide association study of the traditional Kazakh horses

Horses are traditionally used in Kazakhstan as a source of food and as working and saddle animals as well. Here, for the first time, microarray-based medium-density single nucleotide polymorphism (SNP) genotyping of six traditionally defined types and breeds of indigenous Kazakh horses was conducted to reveal their genetic structure and find markers associated with animal size and weight. The results showed that the predefined separation between breeds and sampled populations was not supported by the molecular data. The lack of genetic variation between breeds and populations was revealed by the principal component analysis, ADMIXTURE, and distance-based analyses, as well as the general population parameters expected and observed heterozygosity (He and Ho) and between-group fixation index (Fst). The analysis revealed that the studied types and breeds should be considered as a single breed, namely the ‘Kazakh horse’. The comparison with previously published data on global horse breed diversity revealed the relatively high level of individual diversity of Kazakh horses in comparison with the well-known foreign breeds. The Mongolian and Tuva breeds were identified as the closest horse landraces, demonstrating similar patterns of internal variability. The genome-wide association analysis was performed for animal size and weight as the traits directly related with the meat productivity of horses. The analysis identified a set of 60 SNPs linked with horse genes involved in the regulation of processes of development of connective tissues and the bone system, neural system, immune system regulation, and other processes. The present study is novel and introduces Kazakh horses as a promising genetic source for horse breeding and selection both on the domestic and international levels