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In this study, we used genotyping to determine the genetic structure and molecular identities of apple landraces from six species of Malus Mill. in China, based on the fingerprints revealed by microsatellite markers with tailed primer M13. A total of 46 apple landraces of Malus Mill. selected from the National Apple and Pear Germplasm Repository in Xingcheng, China were genotyped with 14 SSR markers. The primers differentiated all the accessions. At least three SSR primers, CH04h02, CH01f07a and CH04g07, with a higher heterozygosity and Shannon’s information index than other combinations can distinguish all the accessions. All the alleles for these three primers were arranged in descending order, and they were assigned values beginning with 01. Character strings were constituted by combining all the codes of the three primers for every accession. By such means, separate and special molecular identities were obtained for every apple landrace, which could be expressed in the form of a bar code. Using such bar codes, trees can be labeled and scanned, which aids in the identification and tracking of genebank collections. The eight-step method for establishing the molecular identities of apple landraces reported here may serve as a reference when determining the molecular identities establishment of other apple germplasms of Malus Mill. This method might also be used for the establishment of a molecular database to aid the preservation of Malus Mill., which is in imminent danger in China. It may also be used to improve the gene bank management of Malus Mill.

China is a center of diversity for Malus Mill. with 27 native species including 21 wild species and six domesticated species. We applied a set of 19 simple sequence repeat markers to genotype 798 accessions of 17 species (12 wild species and five cultivated species) of Malus originating from 14 provinces in China. A total of 500 alleles were detected. Diversity statistics indicated a high level of genetic variation as quantified by the average values of the effective allele number (Ne), expected heterozygosity (He), and Shannon’s Information Index (I) (10.309, 0.886, and 2.545, respectively). Malus sieversii (MSR; He=0.814, I=2.041, Ne=6.054), M. baccata (MBB; He=0.848, I=2.350, Ne=8.652), M. toringoides (MTH; He=0.663, I=1.355, Ne=3.332), and M. hupehensis (MHR; He=0.539, I=0.912, Ne=0.579) showed a higher level of genetic diversity in this study than the previous studies. MSR and MBB contributed to the origin and evolution of some accessions of M. domestica subsp. chinensis (MDC). However, other accessions of MDC showed a closer genetic distance with MBB and cultivated species, especially M. robusta (MRB), M. asiatica (MAN), and M. prunifolia (MPB). Not all accessions of MDC were descended from MSR in Xinjiang Uygur Autonomous Region of China. This research provides novel insights into the genetic relationships of Malus native to China, which will be useful for genetic association studies, germplasm conservation, and breeding programs.

В свете существенных изменений климата в сторону аридизации актуальными являются вопросы изучения засухоустойчивости и жаростойкости плодовых культур с целью выявления генотипов, наиболее адаптированных к условиям определенного региона. В статье приведены данные за 2019 г. по основным параметрам, характеризующим засухоустойчивость (оводненность, водный дефицит, водоудерживающую способность) и жаростойкости листьев видов родов Malus Mill. и Pyrus L. произрастающих на территории Оренбуржья. Большинство изученных образцов яблони и груши хорошо выносят засушливые условия Заволжско-Уральского региона. Полученные данные и последующие исследования позволят выделить среди множества видов и сортов яблонь генетические формы, наиболее приспособленные к засушливым условиям Заволжско-Уральского региона. Использование перспективных видов, сортов и форм будет способствовать сохранности и продуктивности вновь созданных плодовых насаждений. Среди самых устойчивых форм Malus. сочетающих высокую оценку засухоустойчивости и жаростойкости можно назвать M. fuska, M. zumi, M. kaido., M. baccata Дубки, клоновые подвои 4-3, 19-7, 4-5,Урал 8, Урал 5, ПП 4-4, 57-233, П 8-8, 18-7, 19-10, ОБ 3-4, Урал 5, 62-396, Арм 18, 64-143 и многие другие. У Pyrus наиболее устойчивыми являются: Шоколадка, УГ 1-1, СК-1, №133., In the light of significant climate changes towards aridization, the issues of studying the drought resistance and heat resistance of fruit crops in order to identify the genotypes with the highest adaptability in these parameters are relevant. The article presents data for 2019 on water content, water deficit, water retention capacity and heat resistance of leaves of species of the genus Malus Mill. and Pyrus L. growing in the Orenburg region. All 166 studied samples have different degrees of relative drought resistance and heat resistance. Most of them tolerate the arid conditions of the steppe zone of the Trans-Volga-Ural region well. An impressive list of promising forms is an encouraging result that allows further research on drought and heat resistance of various species and forms in the soil and climatic conditions of the region to continue. The creation of varieties resistant to moisture deficit using the existing gene pool will allow the creation of profitable fruit plantations.

Thirteen sequence-related amplified polymorphism (SRAP) primers combined with polymerase chain reaction (PCR) were used to evaluate the genetic relationships among 24 genotypes of the genus Malus Mill. including Sect. Malus, Baccatus, Sorbomalus and Chloromeles. Out of 115 surveyed fragments, 107 (93.04%) were polymorphic. Coefficients of genetic similarity ranged from 0.538 to 0.868, with an average value of 0.720 between pairs of materials, which indicated the high degree of polymorphism within this species. Cluster analysis showed that all genotypes were divided into six groups. A dendrogram showed that some of the clustered genotypes were largely congruent for geographical distribution. The species in Sect. Malus, Sorbomalus and Chloromeles were separated to a great extent. However, the DNA patterns for some genotype groups did not demonstrate relative agreement in their pedigrees. In Sect. Sorbomalus, M. yunnanesis was independently separated, while M. prattii were clustered in group III with M. bhutanica, M. platycarpa and M. fusca classified into Ser. Kansuenses. Five species originated from the American region were dispersed into two groups within the dendrogram. The conflicts were reflecting their complex genetic backgrounds.

Results of investigations curried out by the scientists of different countries, including molecular genetic studies, on the origin of genus Malus Mill. and their closest congeners, which may form the basis for a revised classification system for the genus and its taxonomic position within the Rosaceae Juss. family are considered.

Tijekom 1998. i 1999. godine u Botaničkom vrtu Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu, bilježeni su vrijeme početka cvatnje, vrhunac i kraj cvatnje na nekim vrstama roda Aesculus L., Magnolia L., Malus Mill., Paulownia Siebold et Zucc. i Viburnum L. Uočeno je da neke od promatranih vrsta svake godine cvatu približno u isto vrijeme. Riječ je o vrstama koje cvatu kasnije u proljeće, te su pod manjim utjecajem temperaturnih vrijednosti u drugoj polovici zime. Druge vrste cvatu jedne godine prije, a druge kasnije, ovisno o tome je li proljeće nastupilo ranije ili kasnije. To su vrste koje cvatu krajem zime ili ranije u proljeće i pod većim su utjecajem toplijeg razdoblja koje može nastupiti u drugoj polovici zime. Pod najvećim je utjecajem temperature vrijeme početka cvatnje, dok su pod manjim utjecajem vrhunac i kraj cvatnje. Naime, vrhunac cvatnje ne mora uvijek slijediti raniji početak cvatnje, pa se moguća oštećenja na biljkama zbog niskih temperatura smanjuju.