Chromosome Association and Giemsa C-banding of Meiotic Chromosomes in Interspecific Hybrid of Alstroemeria ligtu L. hybrid and A.pelegrina L. var. rosea, its Amphidiploid, and Sesquidiploid between the Amphidiploid and the Parents.

Abstract

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.