Adventitious shoot organogenesis from immature leaves of sugarcane (Saccharum spp. hybrid) cultivar Yuetang 03-373 improving shoot proliferation and industrial scale-up of plants

Sugarcane (Saccharum spp. hybrid) cultivar Yuetang 03-373 is a hybrid with superior agronomic characteristics that was obtained from the cross between Yuetang 92-1287 (♀) and Yuetang 93–159 (♂). In this study, transversely cut discs of immature leaves were used to induce adventitious shoots for the first time. Embryonic callus was induced from leaf explants on Murashige and Skoog (MS) medium with 0.5 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.1 mg/l α-naphthaleneacetic acid (NAA). On MS medium containing 0.75 mg/l 6-benzyladenine and 0.1 mg/l NAA, 73.1% of explants from which callus was induced differentiated into adventitious shoot within 30 d and the mean number of adventitious shoot buds was 128.3 per explant. This is many times than regular axillary shoot propagation (mean 5.6 shoots) on the MS medium supplemented with 1.25 mg/l Kinetin (KIN) + 0.1 mg/l NAA. On rooting MS medium containing 0.4 mg/l indole-3-butyric acid (IBA), 0.2 mg L^–1 NAA and 50 g/l sucrose, all shoots rooted. Well-rooted plantlets showed 100% survival in five tested substrates after 60 d. Using this efficient in vitro regeneration system, scaled-up production was achieved to mass produce sugarcane cultivar Yuetang 03-373 for national markets. The results of our genetic diversity study using DNA-based ISSR markers showed that there was no heritable variation in the induction of shoot organogenesis through immature leaves, which provided a shortcut for future vegetative propagation of sugarcane.