November 20, 2018
By Melody M. Aguiba
The government has embarked on a robust “genetic diversity” program of the endangered narra and industrial tree rattan as a commitment to conserve forests amid seemingly irreversible deforestation that threatens economic resources.
The Ecosystems Research & Devt. Bureau (ERDB) has started carrying out DNA analysis of these economically important tree species as a long term support to the National Greening Program (NGP) of DENR.
Genetic variation is the basis of evolution and the catalyst for species to adapt to ever changing environment.
“Assessment of genetic variation among and within populations is essential for the success of any tree breeding and selection programs. It holds vast potentials for the preservation of the forest ecosystems,” said Dr. Sofio B. Quintana, ERDB Director.
Six provinces– Ilocos Sur, Cebu, Iloilo, Marinduque, Nueva Vizcaya and Quezon—has so far been identified as potential sources of good planting materials for narra reforestation.
“The genetic diversity analysis showed that the 6 populations of Pterocarpus indicus Wild (narra) from the 6 provinces have good levels of genetic variation and can serve as good sources of potentially useful genes,” according to ERDB genetic experts Maria Theresa A. Delos Reyes, Gracetine D. Magpantay, Aimee G. Cagalawan, Aida B. Lapis, and Nenita M. Calinawan.
Government has deemed a top priority to conserve forests as a top economic asset as Philippines that has among the most biologically diverse flora with 5% of world’s total.
Narra’s timber is prominent among importers in Asia, Europe, US, and Australia which “accept large volumes of sawn timber at high prices US$600 per cubic meter if it were available,” according to the “Species Profiles for Pacific Island Agroforestry.”
Narra is also known for its medicinal, ornamental, and nitrogen-fixing functions.
1.5 billion trees
ERDB’s project, “2018 Genetic Diversity: A Key Component for Conserving Philippine Forest Trees,” aims to identify trees with molecular markers that indicate high survival rate as part of planting the targeted 1.5 billion trees under the NGP.
“With the increase in global average temperatures, some species of forest trees fail to cope up to such changes. With more genetic variations, it is more likely that some individuals possess alleles (alternative form of genes) that better suit the environment,” said ERDB authors Karol Josef Lucena, Jordan Abellar and Jorge Cyril Viray.
Having less genetic diversity leads to uniformity, with population having individuals less likely to adapt and survive in the changing environment.
While monoculture in agriculture is good for harvesting a good volume of a single crop, it will be a problem when a disease or parasites attack the field in the long run.
Little genetic variation within a species impedes the process of healthy reproduction as evident by the expression of harmful traits in the offspring resulting from inbreeding (mating of genetically related organisms or in human, within one family).
Inbred trees grow slowly, are often deformed and many die suddenly and inexplicably before reaching maturity. Few inbred trees survive and reproduce in natural forest setting.
In 1890, an epidemic had spread across Panama wiping out hectares of banana production. Being genetically identical, banana plants are susceptible to the fungal disease, providing little to no resistance against the disease.
Such scenario ultimately leads to extinction of the population and eventually extinction of the species.
“Knowledge of the extent of genetic diversity in selected narra populations may be used in determining the susceptibility of these narra populations to pests like the ambrosia beetles which are the causative agent of fusarium wilt (Fusarium oxysporum),” said the Delos Reyes, Magpantay, Cagalawan, Lapis, and Calinawan in a scientific paper.
Forestry experts use molecular markers as part of effective reforestation strategy because of the “ease, rapidity and reliability in producing results.”
“One of the factors that caused delay and failure to reforestation in the Philippines is the lack of proper evaluation of individuals (trees) of known origins, which includes both morphological and molecular characterization.”
With knowledge of superior traits of trees species, the combination of superior ones will be chosen as planting materials. Among desired traits are timber quality and durability, fast growth, and disease resistance.
In order for plant geneticists to tell apart genetic variations, they use segments of DNA (deoxyribonucleic acid) sequence of the individuals to mine them out despite the limited availability of whole genome sequences from forest trees species.
These segments of DNA are called DNA-based molecular markers which are widely used in studying genetic diversity, as well as for identification of species.
According to Abellar, ERDB biologist, after collecting the plant material (leaf, stem, or root), careful optimization of protocols follows wherein the DNA of the material is isolated.
This process is called DNA extraction. The process involves breaking the cell wall and cell membrane (cell lysis), removing the organelles, and destroying the nuclear membrane. After these processes, the “purest” DNA can be extracted.
Having a desirable amount of DNA with superior purity, molecular biologists then subject this DNA to a temperature sensitive process that produces millions of copies of it in a matter of an hour or two. This copying process is called DNA amplification or polymerase chain reaction (PCR) discovered by Nobel Prize winner Kary Mullis in 1985.
It involves a series of heating-cooling-heating the DNA.
These temperature changes allow the enzymes and other reagents to copy the target regions (molecular markers) of the DNA.
PCR is an indispensable technique known to be used in medical and clinical laboratory research including forensic science in crime scene investigations.
It also holds a potential swing in improving forensic botany for higher productivity and survivability of forest trees species and for the trees to achieve superiority in growth parameters.
For rattan, the study found Bataan population holding the highest genetic diversity, therefore was rendered as a potential source of genes useful for tree improvement and breeding programs; while for Narra, Ilocos was the most genetically diverse population.
To date, de los Reyes said the diversity of five forest tree species (Narra, Benguet Pine, Bagalunga, Molave, and Ipil) are included in the study Assessment of Genetic Diversity of Priority Forest Tree Species through DNA Analysis of the Genetic Improvement of Priority Forest Tree Species for Quality Wood Production Project.
The species were selected based on the criteria stated in DAO 2010-11 “Revised Regulations Governing Forest Tree Seed and Seedling Production, Collection and Disposition”.
Using these molecular markers, the assessment of Kawayan tinik (Bambusa blumeana Schultes f.) was also completed. Results revealed that the Pangasinan population was the most genetically diverse (Delos Reyes M.A., et al., 2015).
The ERDB genetics researchers used a technology called Random Applied Polymorphic DNA or RAPD as a molecular marker in determining genetic characteristics of individual rattan trees because it is cheaper and simple to use compared to other marker technology.
Because of the limitations presented by RAPD markers, ERDB also utilized a new marker system called Simple Sequence Repeats (SSR) for its other genetic diversity studies.
Moreover, transferability of these SSR markers to progenies planted in Progeny Test Plantation of the Progeny Tests Cum Seedling Seed Orchards study is being documented.
The genetic diversity of these plantations is also being assessed.
The ERDB biologists had found that Limuran Calamus (rattan) in Bataan, Camarines Norte, and Quezon showed enough variation in the populations, making the 3 provinces an ideal source for Limuran rattan planting materials.
Calamus is the largest genera of rattans with 388 accepted species names. Their canes are used for furniture, walking sticks, and flooring and implement handles. Limuran rattan also has potential pharmaceutical uses with bioactive components found to be anti-inflammatory and anti-diarrhetic. Melody Mendoza Aguiba