Genetic Diversity Analysis of Tomato (Solanum lycopersicum L.) with Morphological, Cytological, and Molecular Markers under Heat Stress

Abstract

Tomatoes are usually consumed daily in the human diet. High temperatures reduce the number of tomato yields per year. Heat stress has been considered one of the most prominent causes of alterations in morphological and molecular characteristics in crops that decrease normal growth, production, and yield in diverse plants, including tomatoes (Solanum lycopersicum L.). In this study, we evaluated six tomato lines, namely G1, G2, G3, G4, G5, and G6, at morphological, molecular, and cytological levels under heat stress. The average results of two seasons (2018 and 2019) clarified that the G6, G1, and G2 lines recorded the highest flowering values, as well as some fruit and vegetative growth traits. Furthermore, G6 and G2 had the maximum number of fruits/plant, whereas G2 and G1 produced the highest yield/plant under high temperatures. The number of chromosomes in all lines was 2n = 24, except for G5, in which the number was 2n = 26, whereas chromosome sizes were small, ranging from 323.08 to 464.48 µm. The G1 cultivar was a symmetrical cultivar (primitive), having the highest total form percentage (TF%) and symmetry index (Syi) values and the minimum karyotype asymmetry index (ASK) value, whereas G4 was asymmetrical (advanced). Molecular marker analysis demonstrated that intersimple sequence repeat (ISSR) primers 49A, HB-14, 49A, 49B, and 89B presented the highest values for polymorphism percentage P%, marker index (MI), effective multiplex ratio (EMR), and polymorphism information content (PIC), respectively. In contrast, OP-A3, OP-B3, SCoT 2, and SCoT 12 primers showed the highest PIC, EMR, MI, P%, and resolving power (Rp) values across the studied random amplified polymorphic DNA (RAPD) and start codon-targeted (SCoT) primers. Moreover, ISSR revealed the highest number of unique specific markers (6), followed by RAPD (4) and SCoT (3) markers. Cluster analysis of combined cytological data and data relating to molecular marker attributes separated the G1, G2, and G3 lines into one group, whereas the other lines were clustered in another group. On the whole, the application of combined analysis using morphological, cytological, and molecular genetics techniques could be considered to provide suitable parameters for studying the evolution of the genetic divergence between the studied tomato lines.

Genetic diversity using biochemical, physiological, karyological and molecular markers of Sesamum indicum L

“…The most important aims in cytogenetic investigations are chromosome identification and karyotype study. In the cytological examination, karyotype study is vital for demonstrating origin, polidy, chromosome attributes, and taxonomic and phylogenetic relationships between plants ( Eroğlu et al, 2013 ; Akbar et al, 2020 ; EL-Mansy et al, 2021 ). Karyoevolutionary forms are illustrated and demonstrated by studying karyotype attributes and their formula ( Weiss-Schneeweiss et al, 2013 ; Soliman et al, 2019 ; Soliman et al, 2020 ).…”

Genetic characterization and quantitative trait relationship using multivariate techniques reveal diversity among tomato germplasms

“…Tomato ( Solanum lycopersicum L.) is one of the most relevant productions of the agro‐horticultural sector in not just Ethiopia but also around the world (El‐Mansy et al., 2021; Tolessa et al., 2013; Worku & Sahe, 2018) for its edible fruits. This nutritious fruit is a valuable vegetable which could be taken raw as salad, processed as puree, ketchup, juice, or powder, and cooked as tomato sauce or soup which has been reported to be an effective remediation for sufferers of constipation (Alda et al., 2009; Rehman et al., 2019).…”

Molecular Characterization of Tomato (Solanum lycopersicum L.) Accessions under Drought Stress

“…Several researchers were interested in the natural phenotypic variations which positively affect natural morphological diversity and genetic variations in a diverse population [3,27]. In this study, the analysis of variance for all the morphological characters showed a wide range of variation among tomato accessions, including fruit shape-related perimeter, fruit shape index, curved fruit shape index, and fruit shape index internal.…”

“…These insights have provided the breeders with new knowledge and tools for plant improvement and the ability to detect the variation between species, varieties, and accessions; for example, using several types of DNA molecular markers can be used such as random amplified polymorphic DNA (RAPD), restriction fragment length polymorphism (RFLP), amplified fragment length polymorphism (AFLP), minisatellites, variable number of tandem repeats (VNTRs), and simple sequence repeats (SSRs) [11,[19][20][21]. SSRs are sections of DNA consisting of (1)(2)(3)(4)(5)(6) or (2)(3)(4)(5)(6)(7) base pair units tandemly repeated throughout the genome [20,[22][23][24], to detect the variation degree [9,21,24] or phylogenetic [25][26][27]. The hypervariability character of SSR markers, based on microsatellite DNA loci, enables this method to be the main major in studying plant population genetics [8,20,[28][29][30][31].…”