Production and characterization of alien chromosome additions in shallot (Allium cepa L. Aggregatum group) carrying extra chromosome(s) of Japanese bunching onion (A. fistulosum L.)

Abstract

First and second backcrosses of amphidiploid hybrids (2 n = 4 x = 32, genomes AAFF) between shallot ( Allium cepa Aggregatum group) and A. fistulosum were conducted to produce A. cepa -A. fistulosum alien addition lines. When shallot ( A. cepa Aggregatum group) was used as a pollinator, the amphidiploids and allotriploids set germinable BC 1 and BC 2 seeds, respectively. The 237 BC 1 plants mainly consisted of 170 allotriploids (2 n = 3 x = 24, AAF) and 42 hypo-allotriploids possessing 23 chromosomes, i.e., single-alien deletions (2 n = 3 x-1 = 23, AAFnF). The single-alien deletions in the BC 1 progeny showed dwarfing characteristics and were discriminated from the allotriploids (2 n = 24) and hyper-allotriploids (2 n = 25) by means of flow cytometric analysis. The chromosome numbers of 46 BC 2 seedlings varied from 16 to 24. Eight monosomic additions (2 n = 2 x +1 = 17, AA+nF) and 20 single-alien deletions were found in these BC 2 seedlings. Consequently, six kinds of A. cepa -A. fistulosum alien chromosome additions possessing different chromosome numbers (2 n = 17, 18, 20, 21, 22, 23) were recognized in the BC 1 and BC 2 populations. A total of 79 aneuploids, including 62 single-alien deletions, were analyzed by a chromosome 6F-specific isozyme marker ( Got-2 ) in order to recognize its existence in their chromosome complements. This analysis revealed that two out of 62 single-alien deletions did not possess 6F. One (AAF-6F) out of the possible eight single-alien deletions could be identified at first. The present study is a first step toward the development of a useful tool, such as a complete set of eight different single-alien deletions, for the rapid chromosomal assignment of genes and genetic markers in A. fistulosum .

Molecular and biochemical identification of alien chromosome additions in shallot (Allium cepa L. Aggregatum group) carrying extra chromosome(s) of bunching onion (A. fistulosum L.)

“…Six types of single-alien deletion lines, including AAF-6F described in our previous study (Hang et al, 2004b), have so far been obtained (Fig. 3).…”

“…Identification of extra chromosomes with the help of genetic markers The eight shallot -A. fistulosum monosomic addition plants (2n = 2x + 1 = 17, AA+nF) and 62 single-alien deletion plants (2n = 3x -1 = 23, AAF-nF), including two AAF-6F plants developed previously (Hang et al, 2004b), were used to identify the genomic constitution of each plant. A. fistulosum 'Kujo-hoso' and A. cepa Aggregatum group 'Chiang mai' were also used as controls.…”

“…Three characteristics of the leaf, i.e., number of tillers, number of expanded leaves per tiller, and length of the leaf blade, of hypoallotriploids (2n = 23) described by Hang et al (2004b) were redivided into five types of single-alien deletion lines (AAF-1F, AAF-3F, AFF-4F, AAF-7F, and AAF-8F). In addition, bulb characterizations in six types of singlealien deletion lines (the above-mentioned five lines plus AAF-6F) and two types of monosomic addition lines (AA+6F and AA+8F) were recorded after harvesting.…”

“…Sugar extraction from the pieces of bulbs was performed as described previously (Hang et al, 2004b). A 0.5 ml aliquot of 70% EtOH extracts was vacuum-evaporated to dryness and redissolved in 0.5 ml of Milli-Q water.…”

“…We produced a population of shallot -bunching onion chromosome addition lines via the first and second backcrossings of their amphidiploid hybrids (♀) to shallot (♂) (Hang et al, 2004b). Forty-two hypo-allotriploids possessing 23 chromosomes, i.e., single-alien deletion plants (2n = 3x -1 = 23, AAF-nF), were included in the BC1 progeny.…”