Genome characterization by meiotic analysis, fluorescent in situ hybridization and assessment of some physiological and biochemical parameters of Thai sugarcane cultivars under salt and drought stress

Name: Sarut Thumjamras

LCSH: Kasetsart University -- Dissertations. Ph.D. (Bioproducts ScienceHorticulture) 2018

Classification :.LCCS: QK495.G74

LCSH: Kasetsart University. -- Department of Science -- Dissertations

LCSH: Sugarcane -- Genome mapping

LCSH: Sugarcane -- Genetics

LCSH: Genomes

Abstract: Drought and saline soil are major problems of growing sugarcane in Thailand. Breeding for genotypes that are more tolerant of such environmental stresses requires extensive genomic data and effective screenings for physiological traits. But our knowledge about genetics and genomics of sugarcane cultivars including the Thai sugarcane ‘‘KPS 01- 01-25’’, is still lacking, as research in these fields are greatly complicated due to its highly polyploid nature. As a first step in the genome characterization we analyzed the crop’s karyotype, studied chromosome pairing at meiosis I and performed fluorescent in situ hybridization (FISH) of rDNA and rice BACs as probes. Analysis of mitotic cell complements in early tapetal cells showed that this cultivar has 110 chromosomes. Pollen mother cells at pachytene clearly demonstrated fully paired configurations of the long chromosomes, in which few pairing partner exchanges and loops could be discerned. In diakinesis cells we observed 74.1 % bivalents, 18.6 % univalents, 2.9 % trivalents and 4.4 % quadrivalents. During this stage secondary associations were abundant, but these threadlike structures disappear after metaphase I. FISH with 5S rDNA produced up to ten fluorescent spots, of which 2–5 are often very small, whereas the 45S rDNA probe showed foci on 8–9 chromosomes. Based on our results and that of related studies, we estimate that this sugarcane is composed of 11–12 genomes. We also selected rice Bacterial artificial chromosomes (BACs) containing chromosome 5 sequences that contains genes controlling economically important traits, and used these BACs for FISH on sugarcane chromosome slides. These cross-species chromosome BAC FISH revealed weak signals, and foci were distributed over parts of the chromosomes. Based on these experiments we concluded that cross-species FISH in sugarcane can better be carried out with sorghum BACs as probes. For testing these physiological stress conditions, we compared the Thai (KPS 01-01-25), tolerant (KPS 01-01- 12) and susceptible (LK 92-11) genotypes in assays with different levels of sodium chloride (0-2% NaCl) and polyethylene glycol (0-15% PEG-6000) for a period of 4 weeks. We observed that both the salt and PEG treatments significantly increased the proline and glycine betaine contents in the leaves. The compound solute accumulation can indicate an osmotic adjustment in sugarcane, whereas the chlorophyll stability index and water relation content decreased significantly in treatments with salt treatments by 2% NaCl. In addition, membrane damage rates responded to only high concentrations of PE . The results suggested that sugarcane responds differently regarding organic osmolytes accumulation and its physiological mechanisms in response to NaCl and PEG stress.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Siriluck Iamtham

Role: Thesis Advisor

Name: Hans De Jong

Role: Thesis CO-Advisor

Created: 2018

Modified: 2025-07-01

Issued: 2025-07-01

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2561/sarut-thu-all.pdf

CallNumber: QK495.G74 .S27

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Forestry

Grantor: Kasetsart University

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