Genetic diversity analysis of coconut (Cocos nucifera Linn.) palms selected as survivors against coconut scale insect (Aspidiotus sp.) outbreak infestation in Laguna and Batangas

Date

6-2016

Degree

Bachelor of Science in Agricultural Biotechnology

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Haydee F. Galvez

Abstract

Coconut(Cocos nucifera L.) is an economically important agricultural crop of the Philippines. A massive infestation of Coconut Scale Insect (Aspidiotus sp.) in CALABARZON and Basilan province has posed serious damage to the coconut industry. During the outbreak of the insect pest infestation, survivor and susceptible palms in Laguna and Batangas were selected by Coconut Genomics Project 8 of the Philippine Genome Center. For this study, the genetic relatedness/distance of the survivor coconut palm trees was evaluated in comparison with the susceptible Laguna Tall (LAGT) population. Eighteen (18) polymorphic microsatellite (SSR) markers previously mapped in each coconut chromosome were used. To characterize the genetic relationship among the coconut populations, their allele frequencies, genotype frequencies, mean number of alleles, and Nei?s genetic distance were calculated for each locus and across the 18 SSR loci that cover allof the mapped chromosomes of coconut. Using the NTSYSpc 2.1 software, genetic clustering wasperformedfollowing the Dice coefficient of similarity and the genetic relationship was displayed in a tree diagram through Complete Linkage analysis. The extent of genetic differentiation between the CSI-survivors and susceptible LAGT, and between the distinct large sub-clusters of the sampled coconut palms was determined based on pairwise-F-statistics test results involving the calculated heterozygosity of the 18 SSR loci.The M survivor palms were found to be well-distributed along with the LAGT palms with small genetic differentiation. Based on SSR genetic similarity, a survivor palm (M17)ismost related to the CATD dwarf variety than LAGT coconut. Polymorphic and distinct SSR alleles/bandswere also identified specific to M4 (Q2 allele), M10 (E3 allele) and M11 (A2 allele) survivor palms. The SSR alleles are not present in any of the LAGT individuals nor the CATD B2 sample. While, SSR allele B2 was only detected and shared by CATD B2, and M11 and M17 survivor palms. The observed seemingly resistant phenotype of these survivor palms against CSI infestation may have true genetic inference based on their SSR differentiation from the susceptible LAGT population. The survivor palm-specific SSR alleles are also good starting point to screen for molecular markers associated to CSI host resistance in coconut. Using the progenies from these promising survivor palm selections, the genetics of CSI resistance should be validated under controlled phenotype assay with the aid ofthese survivor palm-specific SSRs, in order to fast track the characterization of candidate resistance loci.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2016 A127 /A46

Document Type

Thesis

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