Abaca (Musa textilis Nee) Breeding in the Philippines - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 272

was attributed to change in chemical constituents. In addition, recent reports
confirmed that abaca mosaic not only reduced the tensile strength of abaca fiber
but also reduced biomass yield, fiber yield, plant height, stalk diameter, and, more
importantly, farmer's income.
Not much is currently known about abaca bract mosaic disease. The first report
of natural infection of abaca with banana bract mosaic virus was reported in the
Philippines in 2000 [ 13 ]. The symptoms of abaca bract mosaic disease are
expressed at any growth stage; an infected plant exhibits stringing of young leaves
with chlorotic stripes. Leaf lamina symptoms consist of spindle-shaped chlorotic
streaks running parallel to the veins which may not be prominent in younger leaves
in recent infection. Older leaves also show raised leaf veins originating from the
midrib which appear like continuous ripples. Greenish to yellowish streaks or
spindle-shaped lesions are present in the petioles but may be absent on petioles of
older leaves showing leaf lamina symptoms (Fig. 12.2 ). When the dead leaf sheaths
are pulled away from the pseudostems, distinctive dark-colored mosaic patterns,
stripes, or spindle-shaped streaks are visible [ 11 ]. The characteristic dark reddish
brown mosaic pattern on the bracts of the inflorescence is the distinguishing mark
for the disease. In the absence of the bracts, abaca bract mosaic symptoms may be
mistaken for abaca mosaic symptoms.
Taxonomy, Domestication, and Genetic Resources of Abaca
Taxonomy
Abaca, ( Musa textilis Nee) or Manila hemp, is endemic to the Philippines. It
belongs to the Musaceae family, a large family that includes majority of the
cultivated banana species and cultivars. The genus Musa is comprised of 30-50
species and many hybrids, majority of which are triploids. Musaceae is divided in
five sections wherein M. textilis belongs to the section Australimusa. It has been
proposed to reduce the sections of this genus to three sections according to the
number of chromosomes and amplified fragment length polymorphism (AFLP)
analysis.
The general morphological structure of M. textilis is similar to that of the edible
banana cultivars, but the plant is more slender, the leaves are smaller, and the fruits
are seeded (Fig. 12.3 ). Only 20 of the more than 400 abaca cultivars in the
Philippines are of commercial importance. Further taxonomic study of the species
is needed.
Spanish friar and botanist Manuel Blanco was the first to classify the Philippine
bananas which also included the description of the wild bananas “butuhan” and
“saging maching,” the abaca, and the “virgin” banana which were all classified
under M. troglodytarum Linn. Abaca was listed by Fr. Blanco with botanical variety
textoria [ 14 ].