菜豆（Phaseolus vulgaris L.）雜交發育變種之遺傳行為

The Inheritance in Developmental Mutants of Phaseolus vulgaris L.

菜豆（Phaseolus vulgaris. L.）不同地綠種P691及P725之種內雜交產生常個體，其發育異常表現如生長受阻，三小葉黃化及下胚軸處變生不定根。雜交代中此等性狀之表現受溫度之影響，高溫（30°/25℃）加速異常表現，低溫則延緩或不完全表現。此發育變種在正反雜交代表現並無差異，同屬於感溫型。遺傳分析顯示兩基因座參予控制異常發育，假設兩基因各為DL1及DL2（表示劑量致死）。DL系統之等位基因具有劑量效應，當兩基因座為顯性同實結合，表現為致死型。其一基因座為顯性同質結合，另一為異型結合則屬次致死型。兩基因座同為異型結合，則呈似F1型。任一基因座或兩基因座為隱性同質結合則為正常型。似F1型為感溫型，次致死型及致死型其發育表現則不受溫度之影響。此形態發育變種受制DL系統，類似變種可藉嫁接方式而複製之。結果顯示來自P691之DL1調節根部因素，P725之DL2調節莖部因素，即DL系統具有差異性表現。DL1作用於根部及DL2作用於莖部之劑量效應造成變種型，而非整個植株之基因型決定變種表現之程度。DL系統影響菜豆生長多方面性狀，顯示此基因座對正常生長居重要之功能。有關變種基因與劑量交感反應，基因之差異性表現及其應用曾加以討論之。

The developmental mutant of Phaseolus vulgaris L. was investigated in the reciprocal crosses of P691 and P725. the morphological expression included stunt growth, chloretic leaves and aerial roots in the hypocotyl. The ocurrence of abnormal F1 was found to be conditioned by two independent loci, tentatively designated as DL1 and DL2. The expression of morphological abnormalities was influenced by temperature; the abnormal phenotype was accentuated by high temperature. The sever ity of phenotypic expression was dependent on the allelic dosage. Plants homozygous dominant at both loci were lethal and plants that were homozygous dominant at one locus and heterozygous at the other locus also perished but at a slower rate. Developmental controls of DL system were examined through reciprocal grafting among parents or F1's. Phenotypes of mutant classes were duplicated by unions of scion and stock derived from diefferent genotype. We suggested that DL1 and DL2 regulated the root and shoot factors respectively, conductive to the mutant type. The allelic dosage of DL1 in the root and DL2 in the shoot rather than the genotype of the whole plant determines the severity of mutant expression. Interaction between temperature and allelic dosage, differential expression of mutant loci and its discussed have been discussed in this paper.