無籽番石榴的形成機制與育種行為

Mechanisms of Seedlessness and Breeding Behavior of Seedless Guava

10.29563/ZHWHGX.201109.0002

陳幼光(Yu-Kuang Chen)

無籽番石榴 ； 育種 ； 多倍體 ； 倍體數間雜交 ； seedless guava ； breeding ； polyploids ； inter-ploidy cvosses

臺中區農業改良場特刊

108號（2011 / 09 / 01）

24 - 31

繁體中文

無籽化為番石榴關於果實性狀方面一個有價值的特性。本研究調查無耔番石榴品種或品系的倍體數、花粉稔性和胚珠發育，以探討造成無籽化的機制。結果發現所有的多倍體均屬無籽，雖然無籽化現象也能發生在二倍體。即使大多數無耔番石榴可產生有活力的花粉，在一些特殊的基因型也找到有雄不稔者。觀察臺灣主要的無耔番石榴品種‘水晶’在開花時的子房，顯示胚珠異常可能是導致其無籽化的原因。此外，無籽和有籽品種或品系間亦進行廣泛的雜交以轉移無籽的性狀，此包括多倍體間和倍體數間的雜交。當利用無籽的二倍體作為花粉源時，與有籽的二倍體能成功雜交。然而，當無籽的二倍體作為雌親時，其著果率就相對較低。多倍體則不論是作為雌親或雄親，一般而言較難用於雜交。從不同二倍體有籽和四倍體無籽親本的雜交組合所獲得的後代，基於流式細胞儀分析結果或其他形態特徵均顯示其為二倍體。除了多倍體外，雜交所得到二倍體後代的種子數均較近似有耔的親本。

Seedlessness is a valuable characteristic in regard to fruit traits of guava. To explore the mechanisms resulting in seedlessness, ploidy level, pollen fertility, and ovule development were investigated in seedless guava cultivars or lines in this study. All of the polyploid guavas are found to be seedless, although seedlessness can also occur in diploids. While most of the seedless guavas produce viable pollen, male sterility can be noticed in a few special genotypes. Ovary observations at anthesis reveal that ovule abnormality might be responsible for seedlessness in 'Shuei-Jing', the main seedless cultivar in Taiwan. In an attempt to transfer the seedless trait, extensive hybridizations were made between seedless and seeded cultivars or lines including inter-polyploidy and inter-ploidy crosses. The seedless diploids when used as pollen sources crossed successfully with seeded diploids. However, seedless diploid guava achieved relatively low fruit set when used as female parent. Polyploid guavas generally were more difficult to use in crosses as either female or male parent. The hybrids obtained from different crosses between diploid seeded and tetraploid seedless parents turned out to be diploids based on flow cytometric analysis and other morphological features. Aside from polyploids, the diploid progeny derived generally contain seed numbers similar to those of the seeded parents.