The Genetic Interaction on the Quantitative Traits of Prescutellar Bristles in Melon Fly, Bactrccera (Zeugodacus) cucurbitae (Coquillett)

瓜實蠅[Bactrocera (Zeugodacus) cucurbitae (Coquillett)]中胸背板剛毛數量性狀之遺傳交互作用

鄭允(Edward Yun Cheng) ； 王志賢(Zu-Hsien Wang) ； 黃毓斌(Yu-Bing Huang) ； 江明耀(Ming-Yaw Chiang) ； 呂秀英(Hsiu-Ying Lu) ； 吳東鴻(Dong-Hong Wu) ； 楊崇民(Chung-Ming Yang) ； 粘君琪(Chun-Chi Nien)

《台灣農業研究》 67卷1期 (2018/03) Pp. 9-15

https://doi.org/10.6156/JTAR.201803_67(1).0002

摘要

The genetics of prescutellar bristles (prsc) in the melon fly, Bactrocera (Zeugodacus) cucurbitae (Coquillett) is polygenic with a quantitative trait of 1 to 20 prsc or more. The field population is polymorphic in regard of prsc and harbors 95% 2prsc phenotype (the major wild type) and 5% 4prsc phenotype (the minor wild type). Several laboratory strains with different numbers of prsc were established for genetic study. When the 2prsc (2P) strain crosses with other phenotypes, instead of blending into the continuous prsc traits, the 2prsc phenotype (2PHT) frequency surged in the F_2 progeny. The reappearing of the parental phenotype in F_2 progeny is unusual in a quantitative genetic event, and is examined by comparing the 2P strain and the multiple prsc (MB) strain in two serial step-up phenotype crosses. All six 2P serial crosses resulted in the 2PHT surge, demonstrating that the 2P strain is the genetic source of the surge. The surge only happened in the F_2 progeny at 22.5% ± 4.0% but not in the F_1 progeny. For the MB strain, the serial crosses with other phenotypes showed no trace of phenotypic surge, and the results of all five MB serial crosses followed the quantitative genetic principle in continuous traits accordingly. The comparative study suggests that the quantitative genetics of prsc can be modified by other genetic factors, although the 2PHT surge mechanism still remains to be investigated. In population genetics, the 2PHT surge is considered to be a contributing factor in the dominance of 2PHT as the major wild type in the field population.

關鍵字

Quantitative genetics ； Prescutellar bristles ； Bactrocera (Zeugodacus) cucurbitae ； Mono-phenotype surge

並列摘要

前期研究中已針對瓜實蠅Bactrocera cucurbitae (Coquillett)中胸背板之prescutellar bristles (prsc)數目屬數量遺傳(quantitative genetics)機制控制，惟在研究中發現野生型(wild type)之2PHT (2prsc phenotype; 2P-strain)與多剛毛品系(multiple prsc phenotypes; MB-strain)雜交時，F_1子代遵循數量遺傳法則，但F_2之頻度分布(phenotype frequency distribution)中，2PHT卻有異常增加之現象，可能有「非屬數量遺傳」之其他機制介入，因此本研究一方面確認前述觀察之確實性，另一方面則藉此探討其原因。本研究係以2P品系及MB品系分別與MB品系之各表現型(phenotypes)進行兩系列之雜交試驗，並比對F_1與F_2之表現型頻度分布，以分析其異同。結果發現凡以2P品系進行之雜交試驗，F_1均依照數量遺傳法則表現，但F_2均出現2PHT表現型增多之情形，平均幅度為22.5% ± 4%，因此2PHT之增加極有可能來自於專限於2PHT之其他因子表現。以MB品系之12PHT與其他表現型之雜交，無論F_1或F_2則依數量遺傳法則表現，並無任何一種prsc表現型突然增加頻度之現象。研究結果顯示瓜實蠅之中胸背板剛毛數確實依「數量遺傳」之機制控制。但田間族群之表現卻以2PHT占95%之野生型，並未依數量遺傳之連續型(continuous traits)表現，因此，其他遺傳因素之介入，至為明顯。而本研究發現之「2PHT突增」(2PHT surge)現象可能為介入遺傳因素之一，而此現象也的確有提升2PHT野生型表現頻率之效益。

並列關鍵字

數量遺傳 ； 小盾板前剛毛 ； 瓜實蠅 ； 隱性基因