Macrostructure of <i>Malus</i> Leaves and Its Taxonomic Significance

Leaves are the most ubiquitous plant organs, whose macrostructures exhibit close correlations with environmental factors while simultaneously reflecting inherent genetic and evolutionary patterns. These characteristics render them highly significant for plant taxonomy, ecology, and related disciplin...

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Main Authors: Yuerong Fan, Huimin Li, Jingze Ma, Ting Zhou, Junjun Fan, Wangxiang Zhang
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/13/1918
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author Yuerong Fan
Huimin Li
Jingze Ma
Ting Zhou
Junjun Fan
Wangxiang Zhang
author_facet Yuerong Fan
Huimin Li
Jingze Ma
Ting Zhou
Junjun Fan
Wangxiang Zhang
author_sort Yuerong Fan
collection DOAJ
description Leaves are the most ubiquitous plant organs, whose macrostructures exhibit close correlations with environmental factors while simultaneously reflecting inherent genetic and evolutionary patterns. These characteristics render them highly significant for plant taxonomy, ecology, and related disciplines. Therefore, this study presents the first comprehensive evaluation of <i>Malus</i> leaf macrostructures for infraspecific classification. By establishing a trait-screening system, we conducted a numerical taxonomic analysis of leaf phenotypic variation across 73 <i>Malus</i> germplasm (34 species and 39 cultivars). Through ancestor-inclined distribution characteristic analysis, we investigated phylogenetic relationships at both the genus level and infraspecific ranks within <i>Malus</i>. A total of 21 leaf phenotypic traits were selected from 50 candidate traits based on the following criteria: high diversity, abundance, and evenness (D ≥ 0.50, H ≥ 0.80, and E ≥ 0.60); significant intraspecific uniformity and interspecific distinctness (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover accent="true"><mrow><mi>C</mi><mi>V</mi></mrow><mo>¯</mo></mover></mrow></semantics></math></inline-formula> ≤ 10% and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>C</mi><mi>V</mi></mrow></semantics></math></inline-formula> ≥ 15%). Notably, the selected traits with low intraspecific variability (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover accent="true"><mrow><mi>C</mi><mi>V</mi></mrow><mo>¯</mo></mover></mrow></semantics></math></inline-formula> ≤ 10%) exhibit environmental robustness, likely reflecting low phenotypic plasticity of these specific traits under varying conditions. This stability enhances their taxonomic utility. It was found that the highest ancestor-inclined distribution probability reached 90% for 10 traceable cultivars, demonstrating reliable breeding lines. Based on morphological evidence, there was a highly significant correlation between the evolutionary orders of (Sect. <i>Docyniopsis</i> → Sect. <i>Sorbomalus</i> → Sect. <i>Malus</i>) and group/sub-groups (B<sub>1</sub> → B<sub>2</sub> → A). This study demonstrates that phenotypic variation in leaf macrostructures can effectively explore the affinities among <i>Malus</i> germplasm, exhibiting taxonomic significance at the infraspecific level, thereby providing references for variety selection. However, hybrid offspring may exhibit mixed parental characteristics, leading to blurred species boundaries. And convergent evolution may create false homologies, potentially misleading morphology-based taxonomic inferences. The inferred taxonomic relationships present certain limitations that warrant further investigation.
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spelling doaj-art-9dfbfedc793549ea94b23d87699d34f82025-08-20T03:28:26ZengMDPI AGPlants2223-77472025-06-011413191810.3390/plants14131918Macrostructure of <i>Malus</i> Leaves and Its Taxonomic SignificanceYuerong Fan0Huimin Li1Jingze Ma2Ting Zhou3Junjun Fan4Wangxiang Zhang5College of Forestry, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Forestry, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Forestry, Nanjing Forestry University, Nanjing 210037, ChinaJiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Nanjing 210014, ChinaJinling Institute of Technology, College of Horticulture, Nanjing 210038, ChinaCollege of Forestry, Nanjing Forestry University, Nanjing 210037, ChinaLeaves are the most ubiquitous plant organs, whose macrostructures exhibit close correlations with environmental factors while simultaneously reflecting inherent genetic and evolutionary patterns. These characteristics render them highly significant for plant taxonomy, ecology, and related disciplines. Therefore, this study presents the first comprehensive evaluation of <i>Malus</i> leaf macrostructures for infraspecific classification. By establishing a trait-screening system, we conducted a numerical taxonomic analysis of leaf phenotypic variation across 73 <i>Malus</i> germplasm (34 species and 39 cultivars). Through ancestor-inclined distribution characteristic analysis, we investigated phylogenetic relationships at both the genus level and infraspecific ranks within <i>Malus</i>. A total of 21 leaf phenotypic traits were selected from 50 candidate traits based on the following criteria: high diversity, abundance, and evenness (D ≥ 0.50, H ≥ 0.80, and E ≥ 0.60); significant intraspecific uniformity and interspecific distinctness (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover accent="true"><mrow><mi>C</mi><mi>V</mi></mrow><mo>¯</mo></mover></mrow></semantics></math></inline-formula> ≤ 10% and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>C</mi><mi>V</mi></mrow></semantics></math></inline-formula> ≥ 15%). Notably, the selected traits with low intraspecific variability (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover accent="true"><mrow><mi>C</mi><mi>V</mi></mrow><mo>¯</mo></mover></mrow></semantics></math></inline-formula> ≤ 10%) exhibit environmental robustness, likely reflecting low phenotypic plasticity of these specific traits under varying conditions. This stability enhances their taxonomic utility. It was found that the highest ancestor-inclined distribution probability reached 90% for 10 traceable cultivars, demonstrating reliable breeding lines. Based on morphological evidence, there was a highly significant correlation between the evolutionary orders of (Sect. <i>Docyniopsis</i> → Sect. <i>Sorbomalus</i> → Sect. <i>Malus</i>) and group/sub-groups (B<sub>1</sub> → B<sub>2</sub> → A). This study demonstrates that phenotypic variation in leaf macrostructures can effectively explore the affinities among <i>Malus</i> germplasm, exhibiting taxonomic significance at the infraspecific level, thereby providing references for variety selection. However, hybrid offspring may exhibit mixed parental characteristics, leading to blurred species boundaries. And convergent evolution may create false homologies, potentially misleading morphology-based taxonomic inferences. The inferred taxonomic relationships present certain limitations that warrant further investigation.https://www.mdpi.com/2223-7747/14/13/1918<i>Malus</i>leaf architecturenumerical classificationancestor-inclined distribution
spellingShingle Yuerong Fan
Huimin Li
Jingze Ma
Ting Zhou
Junjun Fan
Wangxiang Zhang
Macrostructure of <i>Malus</i> Leaves and Its Taxonomic Significance
Plants
<i>Malus</i>
leaf architecture
numerical classification
ancestor-inclined distribution
title Macrostructure of <i>Malus</i> Leaves and Its Taxonomic Significance
title_full Macrostructure of <i>Malus</i> Leaves and Its Taxonomic Significance
title_fullStr Macrostructure of <i>Malus</i> Leaves and Its Taxonomic Significance
title_full_unstemmed Macrostructure of <i>Malus</i> Leaves and Its Taxonomic Significance
title_short Macrostructure of <i>Malus</i> Leaves and Its Taxonomic Significance
title_sort macrostructure of i malus i leaves and its taxonomic significance
topic <i>Malus</i>
leaf architecture
numerical classification
ancestor-inclined distribution
url https://www.mdpi.com/2223-7747/14/13/1918
work_keys_str_mv AT yuerongfan macrostructureofimalusileavesanditstaxonomicsignificance
AT huiminli macrostructureofimalusileavesanditstaxonomicsignificance
AT jingzema macrostructureofimalusileavesanditstaxonomicsignificance
AT tingzhou macrostructureofimalusileavesanditstaxonomicsignificance
AT junjunfan macrostructureofimalusileavesanditstaxonomicsignificance
AT wangxiangzhang macrostructureofimalusileavesanditstaxonomicsignificance