Studies On Embryogenesis To Regenerate Plant And Techniques For In Vitro Conservation In Cassava (Manihot Esculenta Crantz)

The starchy root crop cassava (Manihot esculenta Crantz) in Euphorbiaceae family is ranking fourth of the most important tropical food crop with some of absolute advantages, such as high biomass yielding, higher starch content and poor soil tolerance and biotic stresses. Its starchy storage root provides a source of staple and livelihood for over 600 million people around the world. In China, cassava was known as one of the important bio-energy crop presently, more than 90% of the commercial storage roots was used to process starch and fuel ethanol with a huge market demanding potential.Because of heavy heterozygosity of cassava genome caused by stack propagation and outcross in longtime, cassava conventional breeding is constrained by less selective effect, deleterious "genetic load" and lower propagation index. However, the practice of biotechnology would resolve these problems in broad background. Throughout microspore embryogenesis pathway to develop doubled haploid plants and somatic cell embryogenesis to regenerate plantlets, it will be very important not only to pioneer a novel technique for utilization of heterosis but also for GM breeding, gene discover, rapid regeneration of elite clone, conservation of germplasm and other aspects in cassava.In this research, from three blocks of microspore embryogenesis, somatic embryogenesis and in vitro propagation and conservation, the test map was designed with different factors and levels of culture content and pre-treat condition to screen the key technical parameters during 2003-2005 using SC 8 and other cassava varieties. An effective system for somatic embryogenesis to regenerate plantlets and a program for rapid propagation in vitro of cassava were established primarily. Also the technology for conservation in vitro of cassava clones has been tried and used preliminarily. The main results were shown as followings:1 . A modified medium consists of MS +0.5mg/LCuSO₄ + 2,4-D4.0mg/L or Picloram10.0mg/L + 20g/L sucrose that suitable to callus induction from anther was acquired by complicate selection to each elements affecting culture. Based on it, higher frequent callus have been obtained from anther of five genotypes, SC8, SC5, SC6, SC7 and Wenchang red, simultaneously. And SC 6 is the best with 98% of inducing frequency. It were understood that which kind of ex-plant is better and the moderate sterilized time of...