Inheritance of morphological characters and glycoalkaloids in potatoes of somatic hybrids between dihaploid Solanum acaule and tetraploid Solanum tuberosum

Steroidal glycoalkaloids occur in potatoes and are reported to impart resis tance to phytopathogens including bacteria, fungi, and insects. Because gly coalkaloids can be passed to progenies during breeding programs designed to develop improved potatoes, it is of importance to determine the quality of desired characteristics and the composition of glycoalkaloids of new somat ic hybrids. The objective of this study was to determine the appearance, si ze, and shape (morphological characters) as well as the glycoalkaloid conte nt of potato tubers of somatic hybrids between tetraploid Solanum tuberosum cv. Dejima (2n = 4x = 48 chromosomes) and the dihaploid clone ATDH-1 (2n = 2x = 24 chromosomes) induced by anther culture from Solanum acuale-T (acl- T, 2n. = 4x = 48 chromosomes). Tuber size and shape in somatic hybrids were in accord with these of cv. Dejima, whereas the tuber skin color resembled that of ATDH-1. Thin-layer chromatography, high-performance liquid chromat ography, and gas-liquid chromatography/mass spectrometry studies showed tha t the two steroidal glycoalkaloids (alpha-chaconine and alpha-solanine) wer e present in the tubers of S. tuberosum, whereas acl-T and ATDH-1 tubers we re found to contain alpha-tomatine and demissine. The concentrations of tot al glycoalkaloids in both acl-T and ATDH-1 was >100 mg/100 g of fresh weigh t tuber cortex, much higher than in S. tuberosum. All somatic hybrids, exce pt-one clone, contained four glycoalkaloids (alpha-chaconine, alpha-solanin e, alpha-tomatine, and demissine) derived from the fusion parents. The lack of alpha-tomatine in the remaining clone may be due to somaclonal variatio n. The results show that character expression is influenced by ploidy level and that, total glycoalkaloid levels in most-somatic hybrids were intermed iate between those of the fusion parents. The possible significance of thes e findings for plant-breeding and food safety is discussed.