粗肋草之開花授粉、斑葉遺傳及親緣分析

Abstract

粗肋草為優良的室內植物，近幾年育種盛行，以育出葉斑與葉柄具色彩豐富、明亮的品種為目標。目前品種名稱混雜，多為種間雜交後代，且染色體倍數異常，加上有花期不一、花粉不易產生與貯藏等因素阻礙育種工作的發展。此外，花梗易腐爛萎凋等障礙，容易導致果實敗育，使雜交種子的獲得更不容易。本研究目的在調節花期克服雜交上的障礙、分析親本的基因型與親緣關係，建立粗肋草雜交育種之技術平台，以供未來育種參考。 連續兩年葉施250 ppm GA3，可以提早並集中花期，施用時間可以依各品種所需的到花週數當作參考。此外，本研究並觀察到三個前人未發表的葉斑性狀，分別為葉身中間處有一條寬約佔葉1/3的銀灰色條帶、中肋上覆有白色條斑、具有黃白斑點分布於葉面；依次暫時命名為Vg，Vbr及Vcp。由於粗肋草實生苗不易獲得，目前無足夠的數據推斷葉柄的遺傳機制，但由後代可以觀察到粉柄×粉柄；粉柄×白柄，可以得到具有粉柄的後代。 RAPD分析方面，粗肋草種原遺傳歧異度甚高，可依血統適當分為七群，第I、Ⅱ群與第Ⅲ、Ⅳ、Ⅴ、Ⅵ、Ⅶ群關係較遠，雜交不易成功獲得後代，但以A. brevispathum （Engl.） Jervis f. immaculatum（Siamese Evergreen）(Ⅲ)、A. simplex(Ⅴ)與A. rotundum × A. simplex（11）(Ⅴ)為父本時可與前三群中的品系雜交成功並獲得後代，這些品系可以作為與其它血統雜交的橋樑。A. pumilum(Ⅳ)、rotundum（Ⅴ）與pictum血統(Ⅵ)為遺傳背景較單純的一類，親緣關係與其它粗肋草較遠。A. costatum N.E. Br. var. costatum f. foxii （Engl.） Jervis ‘Foxii Grande’與A. brevispathum 聚成一群（Ⅲ）。第I群中的IB又可分為三群，IB3，為具有紅色色素的一群，血統上與A. rotundum相關，但不產生花粉，因此育種上紅色色素來源，必須利用A. rotundum × A. simplex（11）（Ⅴ）的花粉或者是由A. rotundum × A. simplex與A. nitidum （Jack） Kunth. ‘Curtisii’帶有紅色素基因的雜交後代去獲得。 粗肋草雜交育種應注意花期的調節、授粉的時機與方法，以及環境溼度的控制，將花期集中於6月以前，使果實可在較高溫的情況下發育、提早採收。除了根據葉斑、葉柄的遺傳機制來進行親本的選擇，還要注意遺傳距離與品系間的雜交親和性，提高粗肋草雜交育種的效率。

Aglaonemas are important interior plants. Breeding for cultivars with beautiful spotted leaves and bright color petiole has long been the prevailing goal. However, the perplex cultivar names, the unusual chromosome number resulted from interspecific hybridization, polyploid, timing of flowering, and pollen inactive during storage hinder the breeding. Moreover, the seed aborted due to pedicle rotten is another cause. The objectives of this study were to regulate the flowering and analyze inheritance of leaf variegation and genetic relationship as the reference of the aglaonemas breeding. The application of 250 ppm gibberellic acid (GA3) on leaves of Aglaonemas for continuous two years promoted flowering earlizer and centralize. The timing of application might not be the same for every cultivars or species. As for leaf variegation, three new alleles were proposed in this study. The description of each trait was one-third of the leaf width of silver-gray band in the middle of the leaf, white stripe cover on middle rib, and yellow-white spot dispersed on leaf surface. Thereafter, the three traits were designated as Vg, Vbr and Vcp respectively. In this study, pink petiole seedlings were obtained only in the combination of pink petiole x pink petiole and pink petiole x white petiole. All the combination using green petiole as one parents generated seedlings with green petiole. However, the inheritance of petiole color was not concluded due to the sample size was too small. The result of RAPD anaysis indicated that Aglaonema genotypes are highly diverged and can be clustered into seven groups. The incongruity between the first two groups (I and Ⅱ) and the last five groups（Ⅲ, Ⅳ, Ⅴ, Ⅵ and Ⅶ）are very high, except A. brevispathum （Engl.） Jervis f. immaculatum（Siamese Evergreen）(Ⅲ), A. simplex (Ⅴ) and A. rotundum × A. simplex（11）(Ⅴ) could be the parental parent as crosses to first three groups. Therefore, these cultivars might be the solution to confer the incongruity between the first and the last groups. The genetic background of A. pumilum(Ⅳ), A. rotundum（Ⅴ）and pictum(Ⅵ) were relatively simple as compared with other aglaonemas. A. costatum N.E. Br. var. costatum f. foxii （Engl.） Jervis ‘Foxii Grande’ and A. brevispathum clustered into group Ⅳ which was consistent with the hypothesis that A. costatum has two varieties, var. costatum and var. brevispathum（Ⅲ）, respectively .The IB group to divide into three subgroups. The common character of the ⅡC group, related to A. rotundum, was having red pigment. Individuals of this group would not produce viable pollen and could be the genetic resource of red pigment in any crosses. For the purpose to introuduce red color into other aglaonemas, A. rotundum × A. simplex（11）（Ⅴ）and A. rotundum × A. simplex x A. nitidum （Jack） Kunth. ‘Curtisii’ were suggested to be the paternal parents. In aglaonemas breeding, controling flowering time, pollination timing and technique, and humidity control of inflorescence were three critical factors to ensure the success of pollination. Regulate flowering time to be before June was also suggested to enhance the probability of obtaining matured seed due to provide fruit a warmer temperature while developing. Besides the consideration of the inheritance of foliar variegation and petiole color, genetic distant and incongruity among species were two other important factors while doing distant hybridization among Aglaonemas.