Banana leaf anatomy characteristics related to ploidy levels

ABSTRACT. Many important crops have cultivars with different ploidy and provide a diverse choice of materials for breeding programs. Therefore, it is essential to accurately assess the ploidy of all breeding materials. Increased DNA content is known to have various effects on external and internal morphology, an effect known as the “nucleotypic effect”. Thus, anatomical assessment can be used as a tool for determining ploidy in plants, making the chromosome counting technique or flow cytometry unnecessary. This study aimed to evaluate the leaf anatomical characteristics of banana cultivars and understand the relationship between these features and ploidy levels. Thirteen accessions were evaluated, including diploid, triploid, and tetraploid genotypes, and cultivars, resulting from in vitro propagation after 90 days of acclimatization. Five fully expanded young leaves were collected from each cultivar, fixed in FAA70 (formaldehyde-acetic acid-ethanol) and preserved in 70% alcohol. Transverse and paradermal sections of the abaxial and adaxial regions were taken, and variables such as size and stomatal density, leaf thickness in the midrib and fourth vascular bundle region, and thickness of the epidermis, hypodermis, and parenchyma were measured. Results for leaf thickness, stomatal size, and density proved to be appropriate parameters for characterizing banana ploidy levels.

摘要
诸多重要农作物均拥有不同倍性的品种，为育种项目提供了多样化的试验材料。因此，精准鉴定所有育种材料的倍性至关重要。已知DNA含量增加会对植株内外形态产生多种影响，该效应被称为核型效应（nucleotypic effect）。因此，解剖学鉴定可作为植物倍性检测的手段，无需再使用染色体计数技术或流式细胞术。本研究旨在解析香蕉品种的叶片解剖学特征，并明确这些特征与倍性水平之间的关联。本研究共评估13份种质材料，涵盖二倍体、三倍体与四倍体基因型及品种，所有供试材料均为经过90天炼苗后的离体繁殖植株。从每个品种采集5片完全展开的幼叶，使用FAA70固定液（甲醛-冰乙酸-乙醇）固定，并保存在70%乙醇中。分别制作远轴面与近轴面的横切片和平周切片，并测定多项指标：气孔大小与密度、主脉及第四维管束区域的叶片厚度，以及表皮、下皮层与薄壁组织的厚度。研究结果表明，叶片厚度、气孔大小与密度可作为鉴定香蕉倍性水平的有效参数。