Variation and Genetic Parameters of Leaf Morphological Traits of Eight Families from Populus simonii × P. nigra

Abstract

Leaf morphology in Populus L. varies extensively among sections, species and clones under strong genetic control. P. nigra L. (section Aigeiros), with large and triangular leaves, is a commercial forest tree of economic importance for fast growth and high yield in Europe. P. simonii Carr. (section Tacamahaca) with small land rhomboid ovate leaves performs cold and dry resistance/tolerance in the semi-arid region of Northern China. Leaf morphological traits could be used as early indicators to improve the efficiency of selection. In order to investigate the genetic variation pattern of leaf morphology traits, estimate breeding values (combining ability), as well as evaluate crossing combinations of parents, 1872 intersectional progenies from eight families (P. simonii × P. nigra) and their parents were planted with cuttings for the clonal replicate field trial in Northern China. Four leaf size traits (area, perimeter, length, width) and roundness were measured with leaf samples from the 1-year-old clonal plantation. Significant differences regarding leaf traits were found between and among three female clones of P. simonii from Inner Mongolia, China and six male clones of P. nigra from Casale Monferrato, Italy. The genetic variation coefficient, heritability and genetic variance component of most traits in male parents were greater than these of female parents. Heritability estimates of male and female parents were above 0.56 and 0.17, respectively. Plentiful leaf variations with normal and continuous distributions exited in the hybrid progenies among and within families with the genetic variation coefficient and heritability above 28.49 and 0.24, respectively. Heritability estimates showed that leaf area was the most heritable trait, followed by leaf width. The breeding value ranking of parents allowed us to select the parental clones for new crosses and extend the mating design. Two male parental clones (N430 and N429) had greater breeding values (general combining ability, GCA) of leaf size traits than other clones. The special combining ability (SCA) of the crossing combination between P. simonii cl. ZL-3 and P. nigra cl. N430 was greater than that of others. Eight putatively superior genotypes, most combined with the female parental clone ZL-3, can be selected for future testing under near-commercial conditions. Significant genetic and phenotypic correlations were found between five leaf morphology traits with the coefficients above 0.9, except for leaf roundness. The results showed that leaf morphology traits were under strong genetic control and the parental clones with high GCA and SCA effects could be utilized in heterosis breeding, which will provide a starting point for devising a new selection strategy of parents and progenies.

Leaf morphological traits: ecological function, geographic distribution and drivers

“…叶原基、建立背腹性及调控叶片扁平化等过程, 进 而形成不同大小和形状的叶片 (Ali et al, 2020;Ren et al, 2020)。例如, 近期研究证明, TCP转录因子在 植物叶形态多样化的过程中起到重要作用, 其与转 录抑制因子TIE1和E3泛素连接酶TEAR1相互作用, 共同调控植物的叶形态 (Tao et al, 2013;Zhang et al, 2017)。 目前叶形态的研究主要集中于两个方面。一方 面是叶性状间的权衡关系, 主要研究叶片形态、结 构和生理性状间的关系, 包括叶片大小与数目间的 权衡 (Kleiman & Aarssen, 2007;Whitman & Aarssen, 2009;Huang et al, 2016)、叶形态对叶片生理结构 (如叶脉网络、栅栏组织和海绵组织)和支撑结构(如 小枝、叶柄)间生物量分配的影响 (Milla & Reich, 2007;Niinemets et al, 2007;Yang et al, 2010;Tian et al, 2016;He et al, 2018)以及叶片大小和排列对 叶片光合作用、水分运输等生理过程的影响 (Poorter & Rozendaal, 2008;Pyakurel & Wang, 2014)。 另一方 面是叶形态与环境间的关系及其应用。以往研究发 现, 多个叶形态指标(包括叶片大小、叶片长宽比、 叶缘类型、单复叶等)与环境因子(主要为年平均气 温、 降水量和土壤性质)间具有较强的相关性 (Jacobs, 1999;Royer et al, 2005;Traiser et al, 2005;Adams et al, 2008;Xia et al, 2009;Peppe et al, 2011) (McDonald et al, 2003;Peppe et al, 2011); 在寒冷 气候下叶片边缘通常具有较大、较多的齿, 且叶片 倾向于高度分裂 (Peppe et al, 2011)。此外, 叶形态 对气候变化响应敏感 (Wiemann et al, 1998;Royer et al, 2009b;Guerin et al, 2012;Li et al, 2020b)。因 此, 叶形态的变异能有效反映生境的变化, 常用来 重建古气候 (Wilf et al, 1998;Greenwood et al, 2004;Adams et al, 2008;Peppe et al, 2011;Chen et al, 2014)。 定量叶形态与气候间的关系有助于理解植物 对气候变化的响应 (Dolph & Dilcher, 1980;Fonseca et al, 2000;Peppe et al, 2011), 亦可用来推测全球 气候变化对植被组成和分布的影响…”

Population Variability of Almond-Leaved Willow (Salix triandra L.) Based on the Leaf Morphometry: Isolation by Distance and Environment Explain Phenotypic Diversity

“…This theory is supported by similar occurrences in other pioneer species, with leaf morphology correlating to the specific environments [78], demonstrating additionally greater inter-population variability [76]. Interaction between genetic and environmental factors often results in variation in leaf size and shape traits, which play a crucial role in a plant's ability to capture light and photosynthesise, i.e., in overall plant's fitness [16,27,103,104]. Accordingly, adjustment of leaf morphology by the plants in the variable environmental conditions is the main mechanism in plant adaptation [105].…”

“…High levels of variability, noticeable among different genera as well as within individual species, make leaf morphometric traits valuable in research on population variability [27]. Intraspecific variability, particularly on the population level, might offer beneficial responses to the conditions in the environment, i.e., enable the population to survive [28].…”

Morphological and Anatomical Variations among <i>Alocasia alba</i> Schott Accessions in Bali Botanic Garden

“…This study also found some variations in leaf shapes, sizes of petioles, leaves, peduncles, spathes and each zone of spadix. This phenotypic variation within species is the result of the interaction of environmental and genetic factors that was gradually inherited to the offspring (Ramsey et al 1994;Gonzalez et al 2012;Albarrán-Lara et al 2018;Li et al 2018;Alcántara-ayala et al 2020;Ren et al 2020). The leaf size and shape indicated the diversity of leaf morphological phenotypes (Ren et al 2020).…”