重瓣懸垂日日春之育種

Abstract

中文摘要 日日春[Catharanthus roseus (L). G. Don]為夏季重要花壇與盆花作物，目前已選育重瓣日日春‘桃園’系列，但尚未有重瓣懸垂型品種。本研究採用重瓣直立型‘桃園’系列與單瓣懸垂型‘Cora Cascade’系列、 ‘Mediterranean’系列及‘Boa’系列闡述1)懸垂特性原因、2)懸垂與重瓣、花色等性狀遺傳模式與3)育成重瓣懸垂型新品種。 本研究以徒手切片法調查5種直立型日日春品種與懸垂型日日春‘Cora Cascade’系列、 ‘Mediterranean’系列及‘Boa’系列19品種莖部構造，結果顯示懸垂型品種韌皮纖維細胞無法合成次生細胞壁，停留於纖維始源細胞階段。另染色觀察直立型日日春‘Vitesse Pink’之莖部切片，顯示日日春韌皮纖維次生細胞壁木質素含量低、纖維素含量高，屬於膠質纖維。將‘Vitesse Pink’植株傾斜栽培28天後取彎曲部位莖段橫切面可觀察到張力側韌皮纖維細胞管徑與細胞壁厚度增加，顯示日日春纖維細胞具反應纖維特性，參與植株支持功能。 使用重瓣直立型‘桃園’系列三品種與單瓣懸垂型‘Cora Cascade’系列三品種及‘Mediterranean’系列兩品種雜交、自交與回交，並調查子代族群懸垂性狀，結果顯示F2族群直立型植株與懸垂型植株比例為3:1 (χ2 = 0-2.84)，顯示直立型對於懸垂型為顯性，由一對主效基因控制。若同時觀察重瓣性狀。則F2族群單瓣直立型:單瓣懸垂型:重瓣直立型:重瓣懸垂型植株比例為9:3:3:1 (χ2 = 0.5-7.4)，且回交結果也顯示懸垂基因座與重瓣基因座互相獨立不連鎖。 使用微強度試驗機檢測直立型 ‘Little Pinkie’、‘Vitesse Pink’與懸垂型品種‘Cora Cascade Polka Dot’、‘Cora Cascade Strawberry’與‘Cora Cascade Magenta’之莖部彈性係數，以彈性係數與各節位中不同組織做相關性分析。結果顯示日日春懸垂性狀主要受到韌皮纖維有無影響，無纖維組織之枝條彈性係數較低，較易彎曲，使植株在生長過程中較易倒伏，於移植25天即產生懸垂性狀。而木質部在組織中之比例與近基部較成熟節位之彈性係數呈正相關，無韌皮纖維且木質部含量較低之日日春品種，彈性係數下降，枝條易彎曲且產生最大的彎曲角度與懸垂程度。 本研究使用日日春‘Cora Cascade’系列4品種、‘Mediterranean’系列2品種與‘桃園’系列3品種分析後代族群花色、無花粉雄不稔等性狀之遺傳模式。以帶有杏色花瓣基因之粉紅色花瓣‘Cora Cascade Strawberry’與白色花瓣‘Mediterranean Polka Dot’雜交，其子代粉紅色花瓣與杏色花瓣分離比為1:1 (χ2 = 0.3)，因子代中無白色花瓣個體出現，顯示粉紅色花瓣對於杏色花瓣與白色花瓣為顯性，且粉紅色花瓣由一對基因控制。使用帶有粉色花瓣基因櫻桃紅花瓣單株與杏色‘Cora Cascade Apricot’雜交，其子代櫻桃紅色花瓣與粉紅色花瓣分離比為1:1 (χ2 = 2.37)，顯示櫻桃紅色花瓣對於粉紅色花瓣與杏色花瓣為顯性，且櫻桃紅色花瓣由一對基因控制。紫紅色花瓣‘桃園五號-紅娘’與紫紅色花瓣‘Cora Cascade Magenta’雜交，F2族群分離比紫紅色:粉紅色:白色為12:3:1 (χ2 = 0.01)，顯示紫紅色花瓣對於粉紅色與白色花瓣為顯性，且由一對基因控制。 花冠筒上緣為紅色之 ‘Cora Cascade Polka Dot’、‘Cora Cascade Apricot’、‘Cora Cascade Strawberry’、‘Cora Cascade Magenta’自交後代皆分離出黃色花冠筒上緣植株，且紅色花冠筒上緣與黃色花冠筒上緣植株分離比為3:1 (χ2 = 0.11-3.25)，顯示黃色花冠筒上緣對於紅色花冠筒上緣為隱性，由一對基因控制。 中型紅眼圈‘Cora Cascade Strawberry’自交後代分離出小型紅眼圈植株，中型紅眼圈與小型紅眼圈分離比為3:1 (χ2 = 0.35)，顯示中型紅眼圈性狀相對於小型紅眼圈為顯性，也由一對基因控制。 一代雜交商業品種‘Cora Cascade Polka Dot’與‘Cora Cascade Strawberry’自交後代分離出無花粉雄不稔植株，花藥正常與無花粉雄不稔性狀分離比為3:1 (χ2 = 0.01-2)，顯示日日春無花粉雄不稔性狀由一對隱性基因控制。 使用花瓣邊緣缺刻且呈波浪狀之‘Angel Tutu’與重瓣花型之‘桃園四號-夏雪’雜交，F1自交分析花瓣邊緣缺刻性狀與無花柱之性狀遺傳模式。其F2族群花瓣全緣與花瓣缺刻分離比為3:1 (χ2 = 0.33-3.02)，顯示花瓣邊緣缺刻性狀由一對隱性基因所控制，且與無花柱性狀連鎖，在重瓣性狀表現之遺傳背景下會增強花瓣邊緣缺刻性狀表現，於異結合植株就可觀察到花瓣邊緣缺刻性狀。 以阿拉伯芥NAC Secondary wall thickening promoting factor 1 (NST1)基因為模板與日日春轉錄體做序列比對，顯示日日春有相似的基因序列表現。雖此基因之CDS (coding DNA secquence)序列於直立型‘Vitesse Pink’及懸垂型‘Cora Cascade Polka Dot’之間無差異，但表現量以‘Vitesse Pink’較‘Cora Cascade Polka Dot’高。 本研究由單瓣懸垂品種與重瓣直立品種雜交之F2族群中挑選植株強健、分支性佳之植株，選出3種常見花色單株營養繁殖固定，依日日春品種檢定方法及性狀調查表列之規定調查，選育出世界首見之重瓣懸垂日日春，並將申請品種權保護。

Abstract Periwinkle [Catharanthus roseus (G.). Don] is an important summer bedding and potted plant species. Cultivar with both trailing and double-flower habits is presently limited. The study employs double-flowered and upright ‘Taoyuan’ series, and single-flowered and trailing ‘Cora Cascade’ series and ‘Mediterranean’ series to elucidate 1) mechanism of trailing habit, 2) inheritance of trailing and double-flower habits, and flower color, and 3) to breed new cultivars with both trailing and doulbe-flower habits. Free hand cross sections were made for upright and trailing cultivars at the first to the third internode above cotyledons. Results showed that all 5 upright cultivars had phloem fiber, but respective cells in trailing ‘Cora Cascade’ series, ‘Mediterranean’ series, and ‘Boa’ series did not have secondary wall. Internode below the second leaf pairs from top of upright ‘Vitesse Pink’ were also sectioned, and stained by phloroglucinol-HCl and iodine chloride to reveal lignin and cellulose. Results showed that secondary wall of phloem fiber had low lignin, and high cellulose content, and categorized as gelatinous fiber. Plants of ‘Vitesse Pink’ with 2-3 leaf pairs were tilted-cultivated for 28 days and cross sectioned at bending stems. Phloem fiber at tension side showed increased diameter and thickened secondary wall, indicating the phloem fiber is a reaction fiber and functions as upright growth support. Self-pollination, F1, F2, and backcross generation of upright and double-flowered ‘Taoyuan’ series, and trailing and single-flowered ‘Cora Cascade’ series and ‘Mediterranean’ series were made. Results showed that F1 population between upright and trailing cultivars were all upright, and the F2 population showed 3 : 1 segregation ratio among upright and trailing progenies (χ2 = 0 – 2.84). Trailing habit in periwinkle is recessive to upright habit, and is controlled by a single major gene. In addition, the F2 population showed 9 : 3 : 3 : 1 ratio among upright+single-flowered, trailing+single-flowered, upright+double-flowered, and trailing+double-flowered progenies (χ2 = 0.5 – 7.4). Loci responsible for upright/ trailing and single-/ double-flower habits in periwinkle are inherited independently. Modulus of elasticity (MOE) of upright ‘Little Pinkie’, ‘Vitesse Pink’, and trailing ‘Cora Cascade Polka Dot’, ‘Cora Cascade Strawberry’, and ‘Cora Cascade Magenta’ were measured by microtester. Results of correlation coefficient analysis between MOE and tissue structure showed that trailing phenotype is governed by presence of phloem fiber. Plants that lack phloem fiber tend to have lower MOE and more likely to bend during growth and showed trailing phenotype of 25 days after potting. Moreover, xylem proportion of also contributed to MOE and trailing level, especially for basal stem and more mature position. Periwinkle cultivars without phloem fiber and lower xylem proportion had lower MOE, which had higher bending angle and more trailing level Four ‘Cora Cascade’ series cultivars, two ‘Mediterranean’ series cultivars, and three ‘Taoyuan’ series cultivars were used to study inheritance of flower color and pollen-less male steriling. Flower color of progenies from self-pollination, F1 and F2 population segregated and followed one gene model of dominant rules as: violet > cherry > pink > apricot > white. Progenies from self-pollination of cultivars with red receptacle segregated for 3 : 1 ratio among red and yellow receptacle (χ2 = 0.11 – 3.25). Red receptacle in periwinkle is dominant to yellow receptacle, and is controlled by single gene. Progenies of self-pollinated red medium-eyed ‘Cora Cascade Strawberry’ segregated for small- and medium-sized eye in 3 : 1 ratio (χ2 = 0.35). Red medium-sized eye in periwinkle is dominant to red small-sized eye, and is also controlled by single gene. Male steriling in periwinkle is recessive to fertile male, and is controlled by single gene. Lobules margined ‘Angel Tutu’ was pollinated with double-flowerd ‘Taoyuan No.4-Summer Snow’, and F2 population was made to study petal margin and style-less. Results showed that F1 population all had entire petal margin and style. Progenies of F2 population segregated for entire petal margin and lobules margin in 3 : 1 ratio (χ2 = 0.33-3.02). And style-less trait is linked with lobules margin. Double-flowered plants showed lobules margin even at heterozygous state. NAC secondary wall promoting factor 1 of Arabidopsis thaliana (AtNST1) was blsated with gene sequence of transciptome in periwinkle, and similar sequence was observed. However, coding DNA sequence of CrNST1 in upright ‘Vitesse Pink’ and trailing ‘Cora Cascade Polka Dot’ did not showed difference. CrNST1 expression level is more in ‘Vitesse Pink’than in Cora Cascade Polka Dot’stem. Three vigourous and well-branching double-flowered and trailing plants from F2 population were selected and cutting-propagated. DUS test following announced methods was made to breed first double-flowered and trailing periwinkle in the world.