夏菫之花青素與花色遺傳

Abstract

夏菫(Torenia fournieri)具耐熱耐濕的特性，為熱帶與亞熱帶國家之重要夏季花壇植物，了解花色之花青素組成及遺傳可提升育種效率。以液相層析串聯質譜儀分析商業品種藍紫花‘Clown Violet’、‘Summery Love Violet’、酒紅花‘Clown Burgundy’、桃紅花‘Clown Rose’、黃花‘Summery Love Deep Yellow’與不同花色純系之花冠裂片及花冠筒花青素組成分。結果顯示白花純系P-41、P-52與黃色花冠裂片‘Summery Love Deep Yellow’花瓣中不含花青素，淡粉色及桃紅色以天竺葵素為主要花青素，且淡粉色之色素濃度較低，酒紅色主要花青素為芍藥素，藍紫色內含的錦葵素濃度最高，顏色較深的遠端部位之色素濃度高於較淺的基部部位。 兩白花自交純系P-41及P-52與不同花色純系試交及與商業品種雜交。結果顯示具花青素的花冠(W_)相對無花青素的白色花冠(ww)為顯性；花瓣遠端依花青素呈現的顏色，顯隱性關係為藍紫色>酒紅色>桃紅色>淡粉色。當Hf1基因為顯性時，形成含有飛燕草素的藍紫色花冠(W_ Hf1_ _ _ _ _ )；Hf1呈隱性且Ht1基因為顯性時，形成由矢車菊素及其衍生物組成的酒紅色花冠(W_hf1hf1Ht1_ _ _)；Hf1及Ht1為隱性時，與控制色素濃度多寡的P基因共同生成由天竺葵素組成的桃紅色花冠(W_hf1hf1ht1ht1P_)及淡粉色花冠(W_hf1hf1ht1ht1pp)。黃色因類胡蘿蔔素累積呈現，由C基因控制，基因型擬定為wwC_，可和花青素合成的顏色共同存在，然花青素形成的顏色較深使得黃色色塊無法表現。 白花純系P-41與桃紅及淡粉花冠雜交生成桃紅遠端花色，而另一白色純系P-52與桃紅花冠雜交後代之花冠為酒紅色，顯示P-52具有顯性之Ht1基因，但因W基因與花青素合成之相關基因Ht1具有上位性，W基因呈隱性時，Ht1雖有表達但無法合成花青素。P-52 (wwhf1hf1Ht1Ht1_ _)與桃紅花冠(W_hf1hf1ht1ht1_ _)雜交後，基因互補使得最終表型為相對顯性的酒紅花冠。而P-41的w及Ht1基因皆為隱性(wwhf1hf1ht1ht1pp)，與桃紅花冠雜交後代仍為桃紅花冠。 花冠筒白色與有色純系試交及與商業品種雜交，結果顯示有色花冠筒(D_)可能相對白色花冠筒(dd)為顯性，然白色花冠筒之純系P-52與白色花冠筒且花冠為桃紅色之雜交後代為有色的酒紅色花冠筒，顯示花冠筒亦由Ht1基因共同控制。上瓣雙色與單色純系試交及與商業品種雜交，結果顯示上瓣雙色(U_)相對於單色(uu)為顯性。唇瓣具黃斑與無黃斑純系試交及與商業品種雜交，結果顯示(Yd_)相對無黃斑為顯性(ydyd)。本試驗證明夏菫之花色遺傳可套用矮牽牛的花色基因模型，透過夏菫的花色與基因及花青素的關係可幫助育種者選拔出理想之花色。

Torenia (Torenia fournieri) exhibits heat and humidity tolerance, making it an important summer bedding plant in tropical and subtropical areas. Understanding the inheritance of flower colors can enhance breeding efficiency. Corolla lobes and tube anthocyanin compositions were analyzed for violet-colored commercial cultivars, namely ‘Clown Violet’, ‘Summery Love Violet’, burgundy-colored ‘Clown Burgundy’, rose-colored ‘Clown Rose’, yellow-colored ‘Summery Love Deep Yellow’ and differ-ent flower color from various pure lines. Results showed that both white flower pure lines P-41 and P-52, as well as yellow culitvar ‘Summery Love Deep Yellow’ flower lobe did not contain anthocyanins. Pink-flowered and rose-flowered primarily con-tained pelargonidin as main anthocyanin, while the concentration of pink-flowered was lower than rose-flowered. Burgundy-flowered mainly contained peonidin, Both violet-flowered had the highest concentration of malvidin, the darker distal parts had higher pigment concentration than the lighter basal part. Two white-flowered pure lines P-41 and P-52 were crossed with different flower colors from pure lines and commercial cultivars. Results show that cyanic corolla (W_) was dominant to acyanic corolla (ww). The dominance of distal color on the co-rolla lobe which produced by anthocyanin was violet > burgundy > rose > pink. When Hf1 gene was dominant (W_ Hf1_ _ _ _ _), phenotype was proposed as violet-flowered which mainly composed of delphinidin and its derivatives; when Hf1 was recessive and the Ht1 gene was dominant (W_ hf1hf1Ht1 _ _ _), burgundy-flowered was mainly formed by cyanidin and its derivatives; when both Hf1 and Ht1 were recessive, along with the P gene that controls the concentration of pigments, rose-flowered (W_hf1hf1ht1ht1P_) and pink-flowered (W_hf1hf1ht1ht1pp) was formed by pelargonidin. The yellow coloration was due to carotenoid, controlled by C gene, genotype was des-ignated as wwC_, and can coexist with anthocyanin, but the deeper color formed by anthocyanin covered the yellow part in the phenotype. White-flowered pure line P-41 crossed with rose and pink corollas produced rose corollas, while another white-flowered pure line P-52 crossed with rose corollas re-sulted in burgundy corolla, indicating P-52 had Ht1 gene which was dominant. None-theless, due to the complementary epistasis between W gene and Ht1 gene related to anthocyanin synthesis, when W gene was recessive, Ht1 expression did not result in anthocyanidin accumulation. The white pure line P-52 (wwhf1hf1Ht1Ht1_ _) crossed with rose corolla (W_hf1hf1ht1ht1_ _), results in a complementary gene interaction, producing burgundy corolla. In contrast, Pure line P-41 (wwhf1hf1ht1ht1pp) crossed with rose corolla, resulted in progeny with rose corollas. Crossed with acyanic and cyanic corolla tube from pure lines and commercial cultivars. Results showed that cyanic corolla tubes (D_) might be dominant to acyanic corolla tubes (dd). However, progeny from corsses between white corolla tube P-52 and white corolla tube with rose corollas resulted in burgundy corolla tube. This indi-cated that the corolla tube color was also controlled by the Ht1 gene. Crossed with double color and single color on the upper corolla lobe from pure lines and commer-cial cultivars. Results showed that double color of upper corolla lobe (U_) was domi-nant to single color (uu). Crossed with yellow spot and without yellow spot on the lower corolla lobe from pure lines and commercial cultivars, results showed that the presence of yellow spot on the lower corolla lobe (Yd_) was dominant to the absence of yellow spot (ydyd). The genetic inheritance of flower color in Torenia fournieri could fit the petunia color gene model. Understanding the relationship between the flower color, genes, and anthocyanins can help breeders select the ideal flower color.