Fahad Ramzan

FISH and GISH: molecular cytogenetic tools and their applications in ornamental plants.

Key messageThe innovations in chromosome engineering have improved the efficiency of interrogation breeding, and the identification and transfer of resistance genes from alien to native species.AbstractRecent advances in molecular biology and cytogenetics have brought revolutionary, conceptual developments in mitosis and meiosis research, chromosome structure and manipulation, gene expression and regulation, and gene silencing. Cytogenetic studies offer integrative tools for imaging, genetics, epigenetics, and cytological information that can be employed to enhance chromosome and molecular genomic research in plant taxa. In situ hybridization techniques, such as fluorescence in situ hybridization (FISH) and genomic in situ hybridization (GISH), can identify chromosome morphologies and sequences, amount and distribution of various types of chromatin in chromosomes, and genome organization during the metaphase stage of meiosis. Over the past few decades, various new molecular cytogenetic applications have been developed. The FISH and GISH techniques present an authentic model for analyzing the individual chromosome, chromosomal segments, or the genomes of natural and artificial hybrid plants. These have become the most reliable techniques for studying allopolyploids, because most cultivated plants have been developed through hybridization or polyploidization. Moreover, introgression of the genes and chromatin from the wild types into cultivated species can also be analyzed. Since hybrid derivatives may have variable alien chromosome numbers or chromosome arms, the use of these approaches opens new avenues for accurately identifying genome differences.

Pre-planting Exogenous Application of Gibberellic Acid Influences Sprouting, Vegetative Growth, Flowering, and Subsequent Bulb Characteristics of 'Ad-Rem' Tulip

Tulip (Tulipa gesneriana L.) is a fascinating bulbous cut flower, and also used for potting, bedding, and border purpose. However, under the sub-tropical climatic conditions, quality tulip flower production is severely affected by its non-uniform bulb sprouting, lack or erratic flowering, small flower stalk, and short vase life. Hence, this study was performed to evaluate the potential of gibberellic acid (GA3) on sprouting, vegetative growth, flowering, flower quality, and vase life, including different bulb characteristics of ‘Ad-Rem’ tulip. Tulip bulbs were dipped in aqueous solution of different GA3 concentrations (0, 50, 75, 100, 125, and 150 mg L-1) for 30 min with Tween-20 (0.01%) as a surfactant. Tulip bulbs treated with 100 mg·L-1 GA3 sprouted in significantly less number of days, exhibited higher sprouting percentage, more plant height, leaf area, leaf chlorophyll, photosynthesis rate, flower stalk length, stalk diameter, and fresh and dry flower stalk weight. Moreover, 100 mg·L-1 GA3 application also decreased overall flower emergence time, increased flower size, produced attractive, glowing, and sturdy flowers with increased quality, and extended the vase life of ‘Ad-Rem’ tulip flowers up to 2.9-folds. However, 150 mg·L-1 GA3 application exhibited better results regarding daughter bulblets per clump with a subsequent increase in bulb diameter, and weight compared to other treatments. Additionally, significant correlation was also found among different growth, flower, and bulb characteristics of GA3-treated tulip plants. Hence, 100-150 mg·L-1 pre-planting exogenous application of GA3 may be effective for quality tulip production under the sub-tropical climatic conditions.

Evaluation of F1 and BC1 hybrids of Lilium lancifolium × Asiatic hybrid ‘Chianti’ by morphological analysis and fluorescence in situ hybridization

ABSTRACT Lilium lancifolium Thunb. exhibits wide genetic diversity and numerous genetic traits within progeny populations. Parent morphology affects the distribution and assortment of progeny phenotypes. In this study, morphological analysis and fluorescence in situ hybridization (FISH) were conducted for cross progeny (F1 and BC1). Results showed that F1-1 hybrids had greater plant height than the parents; however, backcross progeny plant height (group 1) was low. Leaf number in both groups was considerably low in F1 hybrid, although high in backcrossed plants. Flower number and days to flower opening were intermediate to those of the parents for F1 hybrids, yet low in BC1 progeny. In group 1, backcross progeny showed small bulb length; however, group 2 progeny showed large bulb length. Positive and negative correlations between the phenotypic traits of parents and progeny confirmed significant variations. According to FISH results, F1-1 and F1-2 hybrids distinctly exhibited nine and eight 45S rDNA loci which were same in position with 45S loci of the parents. In backcross progeny, eight 45S rDNA signals were detected in four BC1 progeny of group 1, while 10 signals were observed in all group 2 progeny, same with the L. lancifolium karyotype. Morphological analysis and FISH helped in scrutinising progeny to obtain hybrids with desirable characteristics.

Chromosomal analysis of Lilium longiflorum x Asiatic hybrids using GISH (genomic in situ hybridization)

In Lilium, a popular horticulture crop, the main objective of crossbreeding is introgression of desirable genes and features into new cultivars. Commercial Lilium cultivars were produced primarily through 2n-gametes or 2x-gametes as parental plants or backcrossing. The primary genetic difference in 2 methods, is the presence of genomic recombination. Especially, GISH (genomic in situ hybridization) among molecular cytogenetic analysis, is the relevant technique to detect genetic information; genome composition, chromosome behavior during meiosis and recombination of hybrids as using their parental DNA as a probe. Based on previous studies, in this research, 12 LA (L. longiflorum x L. Asiatic hybrids) hybrids were analyzed by GISH (genomic in situ hybridization) along with ploidy analysis, and pollen germination tests. The LA hybrids used in this study, showed less pollen germination ability (ranged 0 - 21.74%), but germination of ‘Caesars Palace’ was significantly higher (59.09%). Interestingly, ploidy analysis showed that ‘Caesars Palace’ was tetraploid and ‘Batistero’ had one more additional chromosome from the L genome. Nine of the 12 cultivars exhibited recombination and 3 had only non-recombinant chromosomes; fewer L. longiflorum chromosomes were present in the cultivars than Asiatic chromosomes. Consequentially, it is assumed that 2n-gametes were more common methodology than 2x-gametes for producing commercial cultivars. Moreover, backcrossing tended to be performed with the Asiatic hybrid cultivar.

Application of Genomic In Situ Hybridization in Horticultural Science

Molecular cytogenetic techniques, such as in situ hybridization methods, are admirable tools to analyze the genomic structure and function, chromosome constituents, recombination patterns, alien gene introgression, genome evolution, aneuploidy, and polyploidy and also genome constitution visualization and chromosome discrimination from different genomes in allopolyploids of various horticultural crops. Using GISH advancement as multicolor detection is a significant approach to analyze the small and numerous chromosomes in fruit species, for example, Diospyros hybrids. This analytical technique has proved to be the most exact and effective way for hybrid status confirmation and helps remarkably to distinguish donor parental genomes in hybrids such as Clivia, Rhododendron, and Lycoris ornamental hybrids. The genome characterization facilitates in hybrid selection having potential desirable characteristics during the early hybridization breeding, as this technique expedites to detect introgressed sequence chromosomes. This review study epitomizes applications and advancements of genomic in situ hybridization (GISH) techniques in horticultural plants.