Evaluation of Stable Resistance Expression in Self-pollinated Progenies of Bacterial Wilt Resistant Regenerants Obtained from Leaf Callus of Tomato.

Abstract

The bacterial wilt resistant line LNSR-7 of tomato was isolated from self-pollinated progenies of leaf-callus derived regenerants by directly inoculating a bacterial wilt pathogen Pseudomonas solanacearum into injured roots of tested plants. The subsequent selfpollinated progenies of the line were examined for their fruit quality and resistance expression under natural cultivation conditions in a pathogen-infested tomato field. During three generations of progenies, the tomato plants showing both the bacterial wilt resistance and the high fruit qualities comparable to the parental cultivar were selected in order to fix commercial characteristics of the line. The stable inheritance of the resistance in the subsequent self-pollinated progenies was further examined by directly inoculating the pathogen into the roots of test plants. Inoculated plants were planted in soil heavily infested with the pathogen to ensure exposure to the pathogen. Under these artificial inoculation conditions, the selected line was shown to be highly resistant to the disease. The resistance mechanism in the line was analyzed by examining multiplication and translocation of the pathogen in planta. The precise monitoring of infection behavior of the pathogen was successfully achieved using the genetically marked P. solanacearum. Consequently the present line LNSR-7 strictly limited secondary multiplication and translocation of the pathogen and suppressed the wilt induction by the pathogen.

Rapid detection of phylloplane bacterium Enterobacter cloacae based on chitinase gene transformation and lytic infection by specific bacteriophages

“…These reporter genes were useful for visualizing the localization of marked bacteria in ⁄ on plant tissues and organs. The lux genes were used for genetic marking of E. cloacae (Rattray et al 1995) and, in our laboratory more routinely, for detecting phytopathogenic and non-pathogenic bacteria in the rhizoplane or rhizosphere (Toyoda et al 1993(Toyoda et al , 1997. In our routine approach, luminiferous colonies of lux-marked bacteria were detected by exposing an X-ray film in the dark (Toyoda et al 1993), but the efficacy of the method was largely dependent upon intensive bioluminescence from the colonies.…”

“…The lux genes were used for genetic marking of E. cloacae (Rattray et al . 1995) and, in our laboratory more routinely, for detecting phytopathogenic and non‐pathogenic bacteria in the rhizoplane or rhizosphere (Toyoda et al . 1993, 1997).…”

Genetic approaches for mitigating losses caused by bacterial wilt of tomato in tropical islands

“…In vitro screening of genotypes against R. solanacearum using bacterial toxins, or bacterial populations, can provide an opportunity to generate resistant varieties (Bobisud et al 1996;Toyoda et al 1997). Bobisud et al (1996) reported 40 % to 100 % survivability in somaclones of 'Healani' tomato while its original population had only 0 % and resistant genotype 'Kewalo' had 30 %.…”

The influence of auxin type on the array of somaclonal variants generated from somatic embryogenesis of eggplant, Solanum melongena L.

“…Somaclonal variation is an alternative way to widen the variation in plant breeding (Larkin and Scowcroft 1981), and somaclonal variants which possess useful traits, such as disease resistance (Gengenbach and Green 1977, Sebastiani et al 1994, Toyoda et al 1997) and physiological tolerance (Tyagi et al 1981, Ezura et al 1995, have been selected. In order to apply this technique successfully to crops of interest, an efficient regeneration method and a higher frequency of variants among the regenerated plants are required: these are being sought in eggplant breeding.…”