Articles
GARLIC ROOTS FOR MICROPROPAGATION THROUGH IN VITRO BULBLET FORMATION
One of the detrimental factors for yield decrease in garlic is the viral contamination due to vegetative propagation.
To produce virus-free garlic, shoot tip culture has been widely adopted.
However, it has been still difficult to find out effective technology to replace the conventional seed clove production system for the rapid multiplication of the virus-free clones. In vitro bulblet formation from shoot tip explants has been reported.
However, production of 10–12 bulblets per shoot tip per clove may not be an appropriate alternative to the seed clove system.
Root tips could be efficiently used for the in vitro bulblet formation as they are produced at large number per clove.
Root tips of 8 genotypes were excised from aseptically sprouted cloves of garlic and cultured on Murashige and Skoog (MS) medium containing 1 μM 1-naphthaleneacetic acid (NAA) and 10 μM 6-benzyladenine (BA) for shoot initiation.
Initiated shoots were proliferated on MS medium supplemented with 0.5 μM BA. Multiple shoots were then transferred to growth regulator-free MS medium containing 12% sucrose for bulblet formation.
All the cultures were incubated at 28°C in continuous light.
Genotypic differences in regeneration and bulblet formation were evident among the cultivars used.
Best response was found with ‘White roppen’, a leading Japanese cultivar.
From a single clove, 40 explants could be excised.
Shoots were induced from 95% explants.
An average 7.5 bulblets were formed per explant. ‘White roppen’ produced 285 bulblets from the root tips of a single clove within 4 months.
Out of eight cultivars, five produced bulblets in vitro. The bulblets contained a single clove in all genotypes except for Hichiri (G58), which had bulblet of multiple clove as well.
After harvest of the bulblets, the roots developed on the bulb formation medium were cultured again and bulblet formation was possible.
The bulblets sprouted and formed plants when transferred to soil.
Therefore, the present protocol seems to be an effective alternative of the seed clove system for the rapid multiplication of virus-free garlic clones through continuous bulblet formation.