Meiotic Irregularities in Alstroemeria andina var. venustula (Alstroemeriaceae)

Alstroemeria andina var. venustula (Alstroemeriaceae)的減數分裂不規則性

Andrea Mariel Sanso ； Arturo Federico Wulff

《Botanical Studies》 48卷3期 (2007/07) Pp. 311-317

摘要

Alstroemeria andina是一種多年生，小型草本（5-16公分高），主要分佈在海拔2,800~3,700公尺阿根廷及智利的有限山區。我們分析此族群之個體的減數分裂過程(2n=2x=16)，發現其過程極不規則。其特徵為末期(anaphase)Ⅰ及Ⅱ均有染色質之接橋及斷裂組態。在某一特定細胞於末期Ⅰ接橋組態之最高數目為2個paracentric inversions（發生在可能之異質結合染色質上）雖然異質嵌合體的確存在，但典型的嵌合體幾乎無法偵測到。我們觀察到的類似異質嵌合體可視同為穩藏的異質嵌合體（因為文獻上曾在隱型異質嵌合體減數分裂過程描述過。）我們觀察到高頻率之具小核之四倍體，意謂不平衡孢子之產生頻率相當高。花粉可染色度介於28及30%之間。Alstroemeria屬植物，減數分裂之行為極為規則而且染色質之重組是很罕見的。綜上所述，我們懷疑某些環境因子劇烈地影響到染色體之構造以及減數分裂之調控。本研究乃第一個在野生Alstroemeria屬下族群具明顯減數分裂不規則性之報告。

關鍵字

Alstroemeriaceae ； 染色體 ； 隱藏的異質嵌合體減數分裂 ； 減數分裂行為 ； 花粉染色 ； 構造異質結合

並列摘要

Alstroemeria andina Phil. var. venustula (Phil.) M. Muñoz (sub nom. A. andina Phil. subsp. venustula (Phil.) Ehr. Bayer) is a perennial, small herb, 5-16 cm tall, that occurs mainly at 2,800-3,700 meters above sea level, in populations of limited distribution from Argentina and Chile. The course of the meiosis was analyzed in a population of this taxon (2n=2x=16), and it proved to be highly irregular. It was characterized by presenting bridge and fragment configurations both at anaphases Ⅰ and Ⅱ. The highest number of bridges at anaphase Ⅰ found in one cell was two, suggesting heterozygosity for as many as two paracentric inversions. Typical chiasmata were almost not detectable, even though they actually existed. The chiasmalike structures observed may be regarded as concealed chiasmata as it has been described in cryptochiasmate meiosis. A high frequency of tetrads with micronuclei was observed, implying significant levels of unbalanced gametes. Pollen stainability ranged between 28 and 30%. In Alstroemeria species the meiotic behaviour is highly regular, and the presence of rearrangements is very uncommon. The whole situation led us to suggest that some environmental factors have drastically affected the chromosome structure and the control of the meiotic process. The present study constitutes the first report of remarkable meiotic irregularities found in a wild population of this genus.

並列關鍵字

Alstroemeriaceae ； Chromosomes ； Cryptochiasmate meiosis ； Meiotic behaviour ； Pollen staining ； Structural heterozygosity