2002 Volume 52 Issue 1 Pages 27-33
Alstroemeria ligtu L. hybrid (LH, 2n = 2x = 16), A. pelegrina L. var. rosea (PR, 2n = 2x = 16) and their interspecific hybrids (2n = 2x = 16, 3x = 24, 4x = 32) were analyzed cytologically. In the parental species, the mean chromosome association per pollen mother cell (PMC) at metaphase I in meiosis was 0.04 I + 7.98 II in LH and 0.08 I + 7.96 II in PR. Meiosis proceeded normally in these 2 species and pollen fertility was 98.4 % in the former and 94.9 % in the latter. These 2 species produced many normal seeds by self-pollination. The hybrid (2n = 16) showed partial chromosome association with a mean of 11.18 I + 2.41 II. Abnormal chromosome behavior such as the formation of bridges and micronuclei was observed frequently at anaphase I and II of PMCs or at the early uninucleate stage of microspores, which resulted in low pollen fertility (0.6 %). The hybrid did not produce any normal seeds when self-pollinated or backcrossed with either parent. In the amphidiploid (2n = 32), the mean chromosome association per PMC was 0.82 I + 15.59 II at metaphase I and pollen fertility was 86.3 %. Although the amphidiploid did not produce any normal seeds by self-pollination, it produced normal seeds by the reciprocal crosses with LH. The mean chromosome association in the sesquidiploid (2n = 24) of LH × the amphidiploid was 8.24 I + 7.85 II + 0.02 III and that of PR × the amphidiploid was 8.58 I + 7.66 II + 0.03 III. These sesquidiploids frequently showed chromosome bridges and micronuclei at anaphase I and II of PMCs or at the early uninucleate stage of microspores, and pollen fertility was 14.8 % in the former and 13.0 % in the latter. Although the two types of sesquidiploid did not produce any normal seeds by self-pollination, the former sesquidiploid produced normal seeds by the cross with LH. In LH, the Giemsa C-bands were observed in 7 out of 8 bivalents at metaphase I of PMCs and in 7-7 out of 8-8 chromosomes at anaphase I of PMCs, whereas no C-bands were observed in PR throughout these meiotic stages. These C-band patterns were detected at metaphase I of PMCs in the hybrid, the amphidiploid, and the two types of sesquidiploids.