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Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development

Gibberellin (GA) and paclobutrazol (PBZ) are both plant hormones for stimulating and retardant of plant growth and development, respectively. The role of both hormones in oil palm growth and development is not thoroughly investigated. Therefore, this study focused on the physiological effects of gib...

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Main Author: Chai, Sook Keat
Format: Thesis
Language:English
Published: 2021
Subjects:
Palms - Growth
Gibberellic acid
Online Access:http://psasir.upm.edu.my/id/eprint/104792/1/FBSB%202022%208%20IR.pdf
http://psasir.upm.edu.my/id/eprint/104792/
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spelling my.upm.eprints.1047922023-10-10T07:51:05Z http://psasir.upm.edu.my/id/eprint/104792/ Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development Chai, Sook Keat Gibberellin (GA) and paclobutrazol (PBZ) are both plant hormones for stimulating and retardant of plant growth and development, respectively. The role of both hormones in oil palm growth and development is not thoroughly investigated. Therefore, this study focused on the physiological effects of gibberellic acid (GA3) or PBZ application on young clonal oil palm and its associated molecular responses. It also involved optimization of a tissue preparation procedure for cryosectioning in future transcriptome profiling of inflorescences. Sucrose treatment with snap freezing of fresh oil palm inflorescences provided cryosections with good cellular morphology and higher RNA yields and quality. On phytohormone application, GA3 and PBZ treatments were separately conducted on young clonal palms for 56 weeks. The GA3-treated palms were taller with longer fronds than the control but produced lower biomass. These physiological changes were associated with a higher expression of cell cycle-related genes such as MYB3R-1, E2FB, CK1d, CDK5RAP3 and SRO1 and cellulose synthase CSLC5 (five-fold) and CCR1 (three-fold) for lignin synthesis. In contrast, PBZ application likely blocked GA biosynthesis by suppressing expression of GA biosynthesis genes GA20ox and GA3ox. PBZ-treated palms were shorter in height and frond length with lower biomass. Higher expression of the growth suppressor RCC and two- to eight-fold lower expression of cytoskeletal motor genes actin 3 and kinesin 3, cellulose synthase CESA2, pectin activator WAK3 and pectin lyase-like suggested that PBZ may suppressed cell expansion in leaves by enhancing secondary cell wall rigidity in oil palm. Besides that, lower SPAD values together with two- to five-fold lower expression of chlorophyll synthesis genes UROD, ChlD, LIL3, PORA and CAO suggested that GA3 suppressed chlorophyll synthesis in GA3-treated palms. Conversely, three fold higher GGR expression in leaflets of PBZ-treated palms associating with higher SPAD values suggested that accumulated geranylgeranyl pyrophosphate (GGPP) due to suppression of GA synthesis might be channeled towards chlorophyll synthesis. On reproductive development, late flowering in PBZ-treated palms correlated with suppression of floral activator SOC1 while late flowering GA3-treated palms displayed elevated expression of flowering repressors LSD1 (three-fold) and GATA21 (two- to five-fold) and reduced expression of the flowering accelerator COL5 (three-fold). However, sex of inflorescences was not affected by these treatments. In conclusion, GA3 treatment of oil palm promoted height increment and frond elongation by promoting cell division and elongation but suppressed biomass production. On the contrary, growth retardation following PBZ treatment might be attributed to suppression of cell expansion. Both GA3 and PBZ treatments appeared to delay flowering but did not affect sex determination in young clonal oil palms. 2021-05 Thesis NonPeerReviewed text en http://psasir.upm.edu.my/id/eprint/104792/1/FBSB%202022%208%20IR.pdf Chai, Sook Keat (2021) Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development. Doctoral thesis, Universiti Putra Malaysia. Palms - Growth Gibberellic acid
institution Universiti Putra Malaysia
building UPM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Putra Malaysia
content_source UPM Institutional Repository
url_provider http://psasir.upm.edu.my/
language English
topic Palms - Growth
Gibberellic acid
spellingShingle Palms - Growth
Gibberellic acid
Chai, Sook Keat
Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development
description Gibberellin (GA) and paclobutrazol (PBZ) are both plant hormones for stimulating and retardant of plant growth and development, respectively. The role of both hormones in oil palm growth and development is not thoroughly investigated. Therefore, this study focused on the physiological effects of gibberellic acid (GA3) or PBZ application on young clonal oil palm and its associated molecular responses. It also involved optimization of a tissue preparation procedure for cryosectioning in future transcriptome profiling of inflorescences. Sucrose treatment with snap freezing of fresh oil palm inflorescences provided cryosections with good cellular morphology and higher RNA yields and quality. On phytohormone application, GA3 and PBZ treatments were separately conducted on young clonal palms for 56 weeks. The GA3-treated palms were taller with longer fronds than the control but produced lower biomass. These physiological changes were associated with a higher expression of cell cycle-related genes such as MYB3R-1, E2FB, CK1d, CDK5RAP3 and SRO1 and cellulose synthase CSLC5 (five-fold) and CCR1 (three-fold) for lignin synthesis. In contrast, PBZ application likely blocked GA biosynthesis by suppressing expression of GA biosynthesis genes GA20ox and GA3ox. PBZ-treated palms were shorter in height and frond length with lower biomass. Higher expression of the growth suppressor RCC and two- to eight-fold lower expression of cytoskeletal motor genes actin 3 and kinesin 3, cellulose synthase CESA2, pectin activator WAK3 and pectin lyase-like suggested that PBZ may suppressed cell expansion in leaves by enhancing secondary cell wall rigidity in oil palm. Besides that, lower SPAD values together with two- to five-fold lower expression of chlorophyll synthesis genes UROD, ChlD, LIL3, PORA and CAO suggested that GA3 suppressed chlorophyll synthesis in GA3-treated palms. Conversely, three fold higher GGR expression in leaflets of PBZ-treated palms associating with higher SPAD values suggested that accumulated geranylgeranyl pyrophosphate (GGPP) due to suppression of GA synthesis might be channeled towards chlorophyll synthesis. On reproductive development, late flowering in PBZ-treated palms correlated with suppression of floral activator SOC1 while late flowering GA3-treated palms displayed elevated expression of flowering repressors LSD1 (three-fold) and GATA21 (two- to five-fold) and reduced expression of the flowering accelerator COL5 (three-fold). However, sex of inflorescences was not affected by these treatments. In conclusion, GA3 treatment of oil palm promoted height increment and frond elongation by promoting cell division and elongation but suppressed biomass production. On the contrary, growth retardation following PBZ treatment might be attributed to suppression of cell expansion. Both GA3 and PBZ treatments appeared to delay flowering but did not affect sex determination in young clonal oil palms.
format Thesis
author Chai, Sook Keat
author_facet Chai, Sook Keat
author_sort Chai, Sook Keat
title Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development
title_short Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development
title_full Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development
title_fullStr Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development
title_full_unstemmed Physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development
title_sort physiological and molecular effects of gibberellic acid and paclobutrazol on young clonal palm growth and development
publishDate 2021
url http://psasir.upm.edu.my/id/eprint/104792/1/FBSB%202022%208%20IR.pdf
http://psasir.upm.edu.my/id/eprint/104792/
_version_ 1781706744378949632
score 13.211869

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