Microsporogenesis and embryo sac development in ornamental and cultivated job's tears Coix lacryma-jobi Linn.

Date

3-1990

Degree

Bachelor of Science in Biology

Major Course

Major in Cell Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Liwayway M Engle

Abstract

Microsporogenesis in pollen mother cells (PMCs) and embryo sac (ES) development in young ovules of ornamental and cultivated Job's tears Coix lacryma-iobi were studied chromosome number of two varieties was 2n = 20. The presence of two nucleolar organizing regions (NORs) and a quadrivalent in PMCs at diakinesis were evidences for the tetraploid nature of these plants. Behavior of meiotic chromosomes in both was normal, except for a few laggards at anaphase which were due to delayed disjunction of late-aligning bivalent at metaphase. Only 17.3% of pollen grains were sterile based on a pollen fertility test and these were due to irregular chromosome number like 2n = 18 and 2n = 24 formed from unequal segregation during premeiotic mitosis. the low frequency of irregular chromosome associations, or the few lagging chromosomes observed. Embryo sac studies revealed that somatic apospory is the made of apomixis in Job's tears. This was evidenced by the direct formation of ES with unreduced genome constitution from somatic in the nucellus via keryokinetic divisions. the presence of 31 and 22 aposporic ES per ovule in ornamental and cultivated plants, respectively suggested the possibility of polyembryony.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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