利用標示基因鑑定水稻二倍體花藥植株的來源

Abstract

將含中期單核花粉的水稻花藥培養於改良式的MS培養基之中，大約於培養三週之後，便可看到癒合組織從花藥內長出。在所培養的三千個花藥中，有782個得到癒合組織，頻度約為26%。將花藥癒合組織移至分化培養基，使其繼續生長與分化。98％的癒合組織分化成白苗或綠苗，兩者大約各佔一半。最後得到258稞植株。根尖染色體數目檢查的結果顯示，大部分為單倍體及二倍體，少數是三倍體及四倍體。 以“糯性”性狀為遺傳標示鑑定二倍體花藥植株的來源，發現116稞為同結合個體，一稞為異結合個體。在同結合個體中，糯性與非糯性個體的比率符合1:1之理論分離率。此等結果顯示這些二倍體花藥植株均源自花粉，而在花粉發育的早期有染色體加倍的現象。推測唯一的異結合個體，可能是由染色體數目未減半的花粉發育而來

Rice (Oryza sativa L.) anthers containing mid-uninucleat microspores were cultured on a modified MS medium. Callus was visible about three weeks after the inoculation. Among a total of 3000 anthers that were cultured, 782 (26%) gave rise to callus. Ninety-eight percent of the callus cultures differentiated into albino or green plantlets upon transfer to plant-regeneration medium. A total of 258 plants were finally survived. Chromosome counts revealed that the anther—derived plants were predominantly haploid and diploid; triploid and tetraploid plants were relatively infrequent. Waxy character was chosen as a genetic marker to detect the origin of anther-derived diploid plants. I2-KI staining of mature pollen and selfed seeds of 117 plants revealed that 57 were homozygous nonwaxy, 59 were homozygous waxy, and one was heterozygote. Chi-square test showed that the observed ratio of nonwaxy to waxy was in agreement with the theoretical 1:1 segregation ratio. The results indicate that the anther-derived diploid plants obtained in this study are of microspore origin, and that chromosome doubling must have occurred in the early microspore development. The only heterozygote was postulated to have developed from an unreduced microspore.