Apple Autotetraploids with Enhanced Resistance to Apple Scab (Venturia inaequalis) Due to Genome Duplication-Phenotypic and Genetic Evaluation

Abstract

Among the fungal diseases of apple trees, serious yield losses are due to an apple scab caused by Venturia inaequalis. Protection against this disease is based mainly on chemical treatments, which are currently very limited. Therefore, it is extremely important to introduce cultivars with reduced susceptibility to this pathogen. One of the important sources of variability for breeding is the process of polyploidization. Newly obtained polyploids may acquire new features, including increased resistance to diseases. In our earlier studies, numerous tetraploids have been obtained for several apple cultivars with ‘Free Redstar’ tetraploids manifesting enhanced resistance to apple scab. In the present study, tetraploids of ‘Free Redstar’ were assessed in terms of phenotype and genotype with particular emphasis on the genetic background of their increased resistance to apple scab. Compared to diploid plants, tetraploids (own-rooted plants) were characterized with poor growth, especially during first growing season. They had considerably shorter shoots, fewer branches, smaller stem diameter, and reshaped leaves. In contrast to own-rooted plants, in M9-grafted three-year old trees, no significant differences between diplo- and tetraploids were observed, either in morphological or physiological parameters, with the exceptions of the increased leaf thickness and chlorophyll content recorded in tetraploids. Significant differences between sibling tetraploid clones were recorded, particularly in leaf shape and some physiological parameters. The amplified fragment length polymorphism (AFLP) analysis confirmed genetic polymorphism of tetraploid clones. Methylation-sensitive amplification polymorphism (MSAP) analysis showed that the level of DNA methylation was twice as high in young tetraploid plants as in a diploid donor tree, which may explain the weaker vigour of neotetraploids in the early period of their growth in the juvenile phase. Molecular analysis showed that ‘Free Redstar’ cultivar and their tetraploids bear six Rvi genes (Rvi5, Rvi6, Rvi8, Rvi11, Rvi14 and Rvi17). Transcriptome analysis confirmed enhanced resistance to apple scab of ‘Free Redstar’ tetraploids since the expression levels of genes related to resistance were strongly enhanced in tetraploids compared to their diploid counterparts.

Effect of Meiotic Polyploidisation on Selected Morphological and Anatomical Traits in Interspecific Hybrids of Brassica oleracea × B. napus

“…Furthermore, seed size, stomatal density, and pollen fertility are usually related to the ploidy level [46]. For instance, a positive relationship was found between the ploidy level and stomatal guard cell length and width, and a negative correlation was observed between ploidy level and stomatal density for diploid and triploid Citrus clementina [47] and stomata length and pollen size in diploid and tetraploid tulips [31] and apples [48]. In Brassica, a high correlation between ploidy and stomata lengths was reported for trigenomic hexaploid hybrids (AABBCC) [36].…”

Establishing Tetraploid Embryogenic Cell Lines of Magnolia officinalis to Facilitate Tetraploid Plantlet Production and Phenotyping

“…This can be achieved using a medium that promotes cell proliferation, followed by screening with flow cytometry. Significant phenotypic variations between sibling polyploid clones are known to result from genetic and epigenetic changes occurring during individual polyploidization events ( Podwyszyńska et al, 2021 ; Wójcik et al, 2022 ). The establishment different polyploid cell lines from the same diploid line, which are presumed to represent individual polyploidization events, might expand the phenotypic variations and create novel breeding opportunities.…”

RUSSIAN ADAPTIVE APPLE (Malus × domestica Borkh.) VARIETIES OF VNIISPK — CONTINUITY OF GOALS AND DEVELOPED TECHNOLOGIES (review)

“…Такой состав нутриентов снижает риск хронических заболеваний, улучшает состояние здоровья и повышает адаптационные возможности организма (6,7). Внешний вид (размер, цвет) и аромат -основные факторы привлекательности плодов яблони для потребителя; с экономической точки зрения основное внимание, особенно в последние десятилетия, уделяется технологическим признакам, определяющим, например, возможность применения современных приемов выращивания и уборки, пригодность для переработки, а также адаптивность, урожайность, сроки цветения и созревания, лежкость плодов, их однородность по размеру, устойчивость к болезням (8)(9)(10)(11)(12). Наиболее востребованными направлениями в мировой селекции яблони остаются устойчивость к болезням, вредителям, абиотическим факторам, компактный габитус растения, товарность плодов (13)(14)(15)(16)(17).…”

“…Очевидно, что получаемые полиплоиды могут приобретать новые признаки (11,42,43). При этом у тетра-и гексаплоидных форм многие физиологические и морфологические показатели ниже, чем у диплоидных (11,42,43).…”