Regeneration of plants from Ipomoea cairica L. protoplasts and production of somatic hybrids between I. cairica L. and sweetpotato, I. batatas (L.) Lam.

Abstract

Plants were regenerated from mesophyll protoplasts of Ipomoea cairica L., a wild relative of sweetpotato (Ipomoea batatas (L.) Lam.), and somatic hybrids between I. cairica L. and sweetpotato cv. Xushu 18 were obtained by PEG-mediated method. I. cairica L. protoplasts were isolated from the leaves of in vitro grown plants and cultured in a modified MS medium containing 0.05 mg l -1 2,4-D and 0.5 mg l -1 kinetin. Nine weeks after plating, the obtained small calluses up to about 2 mm in diameter were transferred to solid MS medium supplemented with 0.05 mg l -1 2,4-D and 0.5 mg l -1 kinetin for callus proliferation. Three weeks after transfer, the calluses were transferred to MS medium supplemented with 0-1.0 mg l -1 IAA and 1.0-3.0 mg l -1 BAP and further to hormone-free MS medium for plant regeneration. The frequencies of calluses forming plants ranged from 6.0% to 41.3% based on the different concentrations of IAA and BAP, and 2.0 mg l -1 BAP gave the highest regeneration frequency of protoplast-derived calluses in I. cairica L.. The regenerated plants, when transferred to soil, showed 100% survival. No morphological variations were observed. Mesophyll protoplasts of I. cairica L. were fused with protoplasts isolated from embryogenic suspension cultures of Xushu 18 by PEG-mediated method. The fused products were cultured with the best protoplast culture system of I. cairica L.. Finally, 114 plants were produced from 63 of the 182 calluses derived from the fused protoplasts, and 46 plants of them were confirmed to be somatic hybrids through peroxidase isozyme, RAPD, morphological and cytological analyses.

In vitro selection and identification of sweetpotato (Ipomoea batatas (L.) Lam.) plants tolerant to NaCl

“…This embryogenic suspension culture system has been successfully used in somatic hybridization and genetic transformation of sweetpotato (Guo et al 2006;Yu et al 2007). The objective of this study is to develop an in vitro selection protocol of salt-tolerant sweetpotato plants through the use of embryogenic suspension cultures of sweetpotato and gamma-ray induced mutation.…”

Development and evaluation of a storage root-bearing sweetpotato somatic hybrid between Ipomoea batatas (L.) Lam. and I. triloba L.

“…14 and from petioles of I. triloba were isolated as reported by Guo et al (2006) and Liu et al (1991), respectively. Purified protoplasts of Kokei No.14 and I. triloba were suspended in W5 salt solution (Negrutiu et al 1986), pH 5.8, at a density of 10 6 protoplasts ml -1 , respectively, and then were mixed at a ratio of 2:1.…”

“…So far, some interspecific somatic hybrids have been produced by polyethylene glycol (PEG) or electrically induced fusion between sweetpotato and its wild relatives, but all these somatic hybrids are not capable of producing storage roots, which limits the use of these somatic hybrids in sweetpotato improvement (Liu et al 1992Belarmino et al 1993;Zhang et al 2002;Guo et al 2006).…”

Novel interspecific hybridization between sweetpotato (Ipomoea batatas (L.) Lam.) and its two diploid wild relatives

“…Somatic cell hybridization was also exploited to produce hybrids but only a few combinations were successfully reported. For those hybrids obtained, their wild parents were among the following species: I. triloba (Liu et al 1994), I. lacunose (Zhang et al 2002), and I. cairica (Guo et al 2006). Nevertheless, these somatic cell hybrid plants varied substantially in their chromosome numbers, were morphologically leaned to their wild parent, and few could set storage roots.…”