Anther culture in coconut (Cocos nucifera L.) / Nguyen Thi Thanh Tuyen.

Thesis (Ph.D. - - Horticulture) University of the Philippines, College, Laguna.

Includes bibliographical references.

NGUYEN THI THANH TUYEN, University of the Philippines at Los Banos, September, 1981, Anther Culture in Coconut (Cocosnucifera L.). Major Professor: Dr. Emerita V. de Guzman. —

Another culture in coconut (Cocos nucifera L.) was studied in order to investigate the possibility of inducing haploid plantlet formation from the pollen in culture. Since stage of pollen development is a critical factor in another culture the development of coconut pollen starting from microspore mother cells (MMC) to mature grains in inflorescences of varying ages was determined. Then a correlation between the stages of pollen development and the number of weeks before splitting (WBS) of the spadix was established.

Anthers excised from inflorescence of different ages were grown on the tested basal media added with various supplements to find out the most responsive stage as well as the most Suitable media for coconut anther culture. A high percentage of embryonic grains as assessed by means of aceto~-carmine. Staining was observed in anthers obtained from 3 day-cold pre-treated flower buds at 7°C and inoculated on Y3, Blaydes (B), and Keller (K) basal media supplemented with 6% sucrose, 15% coconut water and 2 ppm NAA alone or in combination with 0.25 ppm 2,4-D, as compared with that on Murashige and Skoog (MS), Bourgin and Nitsch (H) and N6 media with similar added components.

The stage just before, during or immediately after the first pollen mitosis appeared to be the most suitable stages for another culture. Late uninucleate microspores were shown to be inducible in one case.

Various stages in the process of embryogenesis were observed once in anthers cultured on B and K media though the response was faster in the latter. The development of microspore-derived embryos started with the atypical, symmetrical mitotic division of the pollen, leading to the formation of globular, heart-shaped and torpedo embryos. The bipolarity of the in vitro embryos was evidently shown and the suppression in growth of one cotyledon was obvious in heart-shaped and torpedo embryos.

Other variables related to the success in another culture such as the genotypic effect and effect of thermal pre-treatments as well as initial liquid culture, were also evaluated. Among these, the cold pre-treatment given to flower buds before the excision of anthers exerted a positive effect in preserving the pollen viability in culture, as determined by fluorochromatic reaction using fluorescein diacetate (FDA). The pre-treatment was more favorable at 14°C than at 7°C. The duration of pre- treatment was optimum at 4 days for 14°C while 7 days was needed

for 7°C. The effect of cold pretreatment was obviously observed | in 4-WBS anthers, as compared with 7-WBS ones. However, no pollen embryo was obtained in all but the afore- mentioned successful experiment. The inability to reproduce the positive results as previously observed was discussed. The internal factor(s) in the anther which in turn is affected by the condition of the donor plant seems to play a critical role in switching the pattern of development from a gametophytic to sporophytic one resulting in the pollen embryo formation.

Submitted to the University Library 01/07/1994 T-1401