Unnikrishnan, Jennie
(2023)
Systematic analysis of reproductive development in normal and mantled oil palm (Elaeis guineensis Jacq) flowers and fruit.
PhD thesis, University of Nottingham.
Abstract
Oil palm (Elaeis guineensis Jacq.) is the most efficient oil crop in the world; it uses substantially less land and resources and produces more oil than any other oil crop. Even so, to meet the growing palm oil demands due to the increasing global population, per capita consumption rates and biofuel demands, ground-breaking strategies for agronomic and genetic improvement of the commercial planting material are necessary. Clonal propagation through tissue culture has proven to be useful in producing uniform planting materials. However, there are incidences of the deleterious floral homeotic mutant, mantled, in oil palm ramets.
In this study, standardised protocols and analytical parameters for the extraction and characterisation of oil palm inflorescences, bunches and pollen in the context of the mantled abnormality are proposed. Genotyping using twenty SSR markers showed good discriminatory powers and revealed ten ‘off types’. Methylation detection at the EgDEF1 KARMA locus using RsaI showed an 18.75% error in distinguishing mantled from normal. Thus, accurate phenotyping and appraisal of mantled phenotype were achieved through visual scoring of unripe bunches. This novel phenotyping regime allowed quantification of the severity as well as variability associated with the aberrant phenotype.
For selection and extraction of comparable inflorescence samples from normal and mantled ramets, a new developmental classification was formulated, and the field sampling and histology protocols were optimised through trial. The different developmental categories were validated using ANOVA (F probability<0.001) and Fisher’s protected least significant difference test. This developmental classification supplements the previous model for developmental stage prediction and enables precise field identification of key developmental events. Subsequently, a reproductive developmental series for oil palm from early inflorescence development to floral maturity was prepared. This developmental series permitted comparisons between age categories (three-year-old young clone and ten-year-old mature clones), sexes as well as phenotypes (normal and mantled).
Hence, for the first time, mantled reproductive development is compared alongside equivalent normal samples from the same clone, throughout the reproductive developmental process. The mantled phenotype was indistinguishable by histology till pseudocarpels were observable at the developmental category ‘floral triad 3 (FT3)’.
Results revealed three novel features of mantled phenotype. Firstly, in the present set of samples, phenotypic expression of mantled was limited to pistillate flowers. Contrary to previous reports, even the abortive staminate flowers in mantled female inflorescences showed normal development while the pistillate flower of the same triad was mantled. Secondly, analysis of field sampling data revealed a lower incidence of male phase (p<.001) associated with the mantled phenotype. This possible effect of mantled on sex determination indicates an earlier manifestation of mantled phenotype than previously reported. Lastly, pollen samples from mantled ramets showed significantly higher pollen abortion and degeneration and lower pollen health (Chi2 probability <0.001). Functional quality assessment of oil palm pollen grains was done through histochemical approaches and germination tests and pollen from mantled sources was analysed for the first time.
Healthy reproductive development and adequate pollination are vital for the optimal yield of oil palm. The systematic investigations undertaken here is a step towards a more comprehensive understanding of these events in normal and the mantled ramets. Results of previously uncharacterised effects of mantled phenotype call for further investigation into its phenotypic expression. Methodologies and parameters proposed here should be useful for a wide range of research into floral abnormalities of oil palm.
| Item Type: |
Thesis (University of Nottingham only)
(PhD)
|
| Supervisors: |
Massawe, Festo
Wilson, Zoe
Wong, Wei Chee
Mayes, Sean |
| Keywords: |
oil palm, mantled, floral development, tissue culture, microscopy, histology, floral abnormality |
| Subjects: |
Q Science > QK Botany |
| Faculties/Schools: |
University of Nottingham, Malaysia > Faculty of Science and Engineering — Science > School of Biosciences |
| Item ID: |
72310 |
| Depositing User: |
-, JENNIE UNNIKRISHNAN
|
| Date Deposited: |
18 Feb 2023 04:40 |
| Last Modified: |
18 Feb 2023 04:40 |
| URI: |
https://eprints.nottingham.ac.uk/id/eprint/72310 |
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