After close to sixty years of effort, involving three generations of scientists, we are finally close to offering relief to our beleaguered abaca farmers who had been suffering heavy losses due to virus diseases, particularly the dreaded bunchy-top virus.
However instead of welcoming the development, a clueless bureaucrat in the Department of Agriculture has demanded a halt of the multi-location field trials of the bunchy-top resistant hybrids developed by the Institute of Plant Breeding (IPB) at UP Los Baños (UPLB) and funded by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology (DOST-PCAARRD). Multi-location trials are necessary steps to establish whether the claimed traits of good adaptation, high yields and resistance to disease are attained when candidate varieties are grown under diverse, actual farming conditions.
The same officer has likewise demanded that a 10-hectare field trial in Leyte jointly launched by Specialty Pulp Manufacturing Inc. (SPMI) and the National Abaca Research Center in Visayas State University be terminated. This joint public-private undertaking which is independent of the plant breeding institution to ensure objectivity, was designed to gather conclusive data on the suitability of the new hybrids for commercial propagation for paper and pulp which are now the dominant uses of abaca fiber (not so much as cordage, anymore).
The concern of the fore-mentioned bureaucrat is the lower fiber quality of the new materials which allegedly could potentially damage the reputation of Philippine abaca. He described the new hybrids as “monsters or new Frankenstein species.” Obviously not knowing any better he ridiculed the species hybrid approach adopted by the UPLB plant breeders as analogous to “cross breeding a dog and cat and expect a horse to come out.”
He further challenged the personal integrity of the UP scientists asserting that “their bloated egos are sabotaging the Philippine abaca fiber industry! And even worse, he insinuated very unkindly that the proponents of the DOST-PCAARRD- funded project were money-driven.
Species hybridization followed
by backcrossing as a classic plant breeding technique
In the first place, species hybridization followed by repeated backcrossing is a classic plant breeding technique when the desired traits (genes) cannot be found in the cultivated species. To demonize and ridicule the method betrays an utter lack of understanding of basic biology and genetics.
The bunchy-top virus diseases is inflicting further hardship on our already impoverished abaca farmers. Abaca plants infected with the virus get stunted and ultimately die off. In fact, the disease totally wiped out abaca plantings in Laguna, Cavite, Batangas and Davao in the 1920s.
Replanting with susceptible traditional varieties is futile because the new, clean planting materials are re-infected in no time at all. But with the new virus-resistant hybrids, the affected farmers need not give up on their infected abaca farms because they can now safety rehabilitate their farms.
The bunchy-top virus is biologically transmitted by aphids. However, control of the aphids with insecticides is useless because aphids feed on many other alternative hosts. The aphids from the surrounding vegetation will readily re-colonize the abaca plants after spraying.
Worse, the aphids hide in the whorl of the leaves which in the mature abaca are 2–3 meters above the ground. The pesticides spray drifts end up in the faces and arms of the poor applicators.
Thus, the only practical economic and sustainable solution is to incorporate genetic resistance into the best abaca varieties. Unlike with the use of pesticides, the farmers will not bear recurring costs because the technology is built into the plants. The technology will get to small farmers at no cost to them since the varieties are being developed at government expense as a public good.
Exhaustive tests sixty years ago failed to identify resistant varieties among the traditional abaca varieties. Hence, our plant breeders had to look for resistance from related Musa (banana) species.
One such species was PACOL (Musa balbisiana). Pacol is robust growing like the saba banana but not edible because it is very seedy. The fiber yield is high but they are of inferior quality compared with true abaca.
Moreover, there is another indigenous banana called CANTON which some farmers raise as a substitute for abaca. Canton fibers are cheap but some farmers nevertheless produce them because Canton is disease resistant so at least they earn some income.
Chromosome studies conducted by the late Ramon Valmayor later revealed that Canton was in fact a naturally occurring hybrid between pacol and abaca. Thus, far from being strange “monster and Frankenstein species” the new IPB hybrids were simply improved versions of the native canton.
Canton which is a first generation (F1) hybrid between pacol and abaca received 50% of its genes from abaca. Canton is resistant to bunchy top tissue but its fiber is inferior to that from abaca. In order to recover more of the desirable fiber genes, the F1 was crossed back to the abaca parent. Backcrossing to the desirable parent (abaca) progressively increases the genomic contribution of abaca in the resulting progeny. Thus, the Backcross (BC) 1 progenies already possess 75% of the abaca genome.
The BC2 selections which are now being tested have 87.5% of their genome coming from abaca. The next round of backcrossing (BC3) will bring the abaca content to 93.7%, by which time it is almost completely like abaca.
However the backcrossing procedure is not as simple and straight forward as described above. Pacol and abaca have different chromosome numbers (22 vs 20). The F1 hybrids were trisomics and the succeeding progenies were highly sterile. Hence the inordinate delay.
of new hybrids
The new hybrids are vigorous and can give yields of 1.50 metric tons of fiber per hectare per year. Their fiber recovery is 20–30% higher compared with traditional abaca varieties.
Unlike abaca varieties which require partial shade, the new hybrids turned out to be agronomically more versatile because they are adapted to full sunlight.
This abaca hybrid could therefore serve as a good pioneer reforestation species. The full-grown hybrid abaca pioneer plants can serve as nurse crops to the tree seedlings (both introduced fast growing and indigenous timber species) in the final reforestation step. The immediate income from fiber extraction can very well provide for the cost of weeding and maintenance until the timber species are fully established
Potentials for pulp,
paper and textiles
Initial laboratory tests conducted by the Forest Products Research and Development Institute (FPRDI-DOST) revealed that the fibers of the new hybrids were not as strong as abaca and therefore will not do as well for cordage making. But the difference is not much. The tensile strength score of the best hybrid was 66 versus 67 and 71 for the abaca reference varieties Abuab and Inosa, respectively.
However in the matter of suitability for pulp and paper making, the pulp from the new hybrids passed the two international pulping standards: 1) Rated Very Promising using the Runkel Ratio (average of 0.50, significantly lower and better than the threshold of 0.75), and 2) Rated Favorable applying the Muhlstep ratio (average of 55%, again significantly lower and better than the threshold of 80%).
More studies are going on to establish the potential of the new abaca hybrids to produce nanocellulose crystals and microfibrils. Cellulose microfibrils (which are renewable and degradable) are increasingly preferred worldwide as raw materials for paper making, composites, packaging, coating, biomedicine and automotive panels.
Likewise textile researchers at the Philippines Textile Research Institute (PTRI-DOST) have preliminarily concluded that physical and chemical properties of the new abaca hybrids are comparable with true abaca varieties for textile processing.
The tensile strength of fibers from the new hybrids is lower than that from traditional abaca varieties. However, the hybrids have higher fiber recovery in spinning and higher abaca content in the yarn composites. Of potential great interest is the observation that the fiber strands of the hybrids are three times finer than abaca. The finer but weaker fiber from the hybrids can be twisted into 2–3 ply to make them strong. These very fine, soft fibers will be appreciated by local handloom weavers in developing materials more suitable for apparels and home textiles.
The hybrids now undergoing final testing for adaptation, productivity and resistance to bunchy-top virus is a fine example of what Filipino scientists can do to help our people. This was achieved by our scientists very much on our own without foreign assistance, albeit it took a very long time.
The fibers coming from the virus-resistant backcross progenies being evaluated have slightly less tensile strength than the true abaca varieties making them less desirable for cordage purposes.
But they are comparable with traditional abaca varieties for pulp, paper and textile and other industrial purposes which are increasingly the dominant and more profitable uses of abaca.
These Backcross 2 progenies possess 87.5% of their genome coming from abaca. Hence their agronomic, physical and chemical properties are comparable, and sometimes better than the abaca parent. The next round of backcrossing will bring the abaca genome content to 93.7% which is almost completely like abaca.
Moreover applying the science of transcriptomics and large-scale high throughput DNA sequencing, Maria Cecilia Reamillo and National Scientist Dolores Ramirez of the College of Arts and Sciences, UPLB were able to identify 66 genes closely linked with fiber quality. Thirty-five of the fiber genes were highly expressed in abaca, and another nine in pacol.
With molecular marker techniques, it should be possible to stack (pile up) the fiber quality genes from both parents. The end-product will be a hybrid with even stronger fiber properties than the original abaca.
The same is possible with genes for resistance to the virus. Six resistance genes were identified, of which three were uniquely expressed in abaca, and two found in pacol. If these resistance genes from both parents are brought together, in the future we may have hybrids even more resistant to the virus than the wild parent.
It is therefore foolish to stop now.
Dr. Emil Q. Javier is a Member of the National Academy of Science and Technology (NAST) and also Chair of the Coalition for Agriculture Modernization in the Philippines (CAMP).
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