報春苣苔屬植物之葉片及花朵性狀遺傳與選育和耐熱性評估

Abstract

報春苣苔屬(Primulina)植物葉片及花朵形態豐富，富觀賞性可作室內盆花而受歡迎。目前有關本屬育種之相關資訊甚少，本研究以市面易取得之報春苣苔原生物種及栽培品種為材料，研究花粉貯藏及種間雜交之親和性、調查葉片與花朵性狀之遺傳、另探討溫度對花粉萌發之影響與生理指標比較，並選育具白脈或裂葉、花朵數多、花朵具花青素或特殊花色，且植株小型之優良盆花品系。 取柳江報春苣苔(P. liujiangensis)、㟖崗報春苣苔(P. longgangensis)、龍州小花苣苔(P. longzhouensis)、寧明報春苣苔(P. ningmingensis)及中越報春苣苔(P. sinovietnamica)之新鮮花粉於22、4及-20℃，20%-35%相對溼度環境下貯藏0、1、2、4、8週，並於25℃環境以含10%蔗糖之培養基(Brewbaker and Kwack's medium)檢測萌發率。綜合顯示以-20℃貯藏四週內可維持最佳萌發率及生長表現；而㟖崗報春苣苔花粉貯藏性最佳，中越報春苣苔耐貯性最差。 取市面常見之10個物種與四個栽培品種進行自交或雜交，結果顯示參試栽培種無法自交或作為花粉親、檢測花粉亦無萌發，僅‘Rachel’作種子親與柳江報春苣苔雜交可得後裔。於23℃環境下原生種自交成功率約為61.3%；種間雜交成功率則為66.4%，61個雜交組合中有56個授粉成功；47個組合成功得到雜交後裔。不同演化支(clade)之遠緣雜交可能致種子數下降、萌發天數增加及後裔雄不稔。種莢大小與內含種子數呈二次曲線相關，莢長約30 mm時種子數最高。 取葉片白脈物種自交，顯示後裔可能皆為白脈或呈3白脈：1綠脈之分離比、取白脈與綠脈物種之雜交後裔可能皆為白脈或呈1白脈：1綠脈之分離比；脈紋型與網紋型白脈物種之雜交後裔皆為網紋型或為1網紋型：1脈紋型之分離比。深裂葉與全緣葉物種之雜交後裔皆為中間型；鋸齒葉與全緣葉物種雜交後裔皆為鋸緣。取葉片具花青素物種自交或雜交，後裔葉片皆有不一致之花青素累積。 取有色花冠筒物種自交或與白色花冠筒雜交，後裔花冠筒皆具花青素表現；花冠裂片亦為如此。具花青素花冠大致可區分為紫色系、紫紅色系及粉紅色系，同色系物種之雜交後裔皆為同色系；不同色系雜交後裔之花色皆類似於親本花色疊加，顯示可能為不完全顯性。花喉具黃斑物種之自交後裔表現與親本相似；與無黃斑物種雜交則會得到淡黃斑表現。取花冠具脈紋之物種與無脈紋物種雜交，後裔皆具脈紋表現。親本花冠長度不同時，後裔花冠長度介於之間或略偏向較大之親本。 取柳江報春苣苔、龍州小花苣苔、寧明報春苣苔及中越報春苣苔新鮮花粉於5 至45℃培養並計算萌發溫度三基點。結果顯示萌發最適溫度以柳江報春苣苔26.2℃最高；中越報春苣苔20.4℃為最低。萌發最高溫度以柳江報春苣苔及龍州小花苣苔較為相近而中越報春苣苔最低。35/30℃栽培下顯著降低寧明報春苣苔和中越報春苣苔葉片之光系統II最大光子利用效率；但可顯著降低柳江報春苣苔、龍州小花苣苔及寧明報春苣苔葉圓片於51℃水浴後之相對傷害值。 取河池報春苣苔(P. hochiensis)、柳江報春苣苔及河池報春苣苔×柳江報春苣苔選拔單株栽培於25/20、30/25及35/30℃。顯示河池報春苣苔及雜交後裔植株外觀以35/30℃栽培下較小。35/30℃降低親本及後裔之新生葉面積，並顯著降低河池報春苣苔及雜交後裔葉片光系統II最大光子利用效率測值，然雜交後裔測值仍高於河池報春苣苔。親本及雜交後裔葉片相對傷害值曲線中點溫度隨栽培溫度上升而提高，35/30℃處理下雜交後裔葉片相對傷害值曲線中點溫度及對應之相對傷害值表現皆介於親本間。 本研究綜合表觀性狀表現，自雜交組合中挑選四個具白脈或裂葉表現、花朵數多、花冠具花青素或特殊花色，且植株大小適合9 cm盆栽培之優良品系。並藉由花粉萌發及生理指標初步建立報春苣苔耐熱性之評估方式。

Primulina, with diverse leaf and floral traits, exhibits high ornamental value and is appreciated as an indoor potted plant. However, information on breeding for this genus remains limited. In this study, readily accessible species and cultivars of Primulina were used to evaluate pollen storage conditions and interspecific hybridization. Additionally, inheritance of leaf and floral traits was investigated. The effect of temperature on pollen germination was compared with physiological indicators, and the inheritance of heat tolerance was examined. Fresh pollen from P. liujiangensis, P. longgangensis, P. longzhouensis, P. ningmingensis, and P. sinovietnamica was stored at 22°C, 4°C, and -20°C with relative humidity of 20–35% for 0, 1, 2, 4, and 8 weeks. Results indicated that pollen stored at -20°C retained the highest viability within 4 weeks. Among the species, P. longgangensis showed the best storability, while P. sinovietnamica the lowest. Ten species and four cultivars were subjected to self- and cross-pollination. All tested cultivars failed to self-pollinate or act as pollen parent, with no pollen germination observed. Only the cross ‘Rachel’ × P. liujiangensis produced viable progeny. The self-pollination success rate of species was 61.3%, while the interspecific hybridization success rate was 66.4%, with 56 out of 61 crosses resulting in successful pollination and 47 crosses yielding hybrid progeny. Distant hybridization between different clades resulted in reduced seed number, increased days to germination, and male sterility in offspring. Capsule size showed a weak positive correlation with seed number. The size of the capsule is related to the number of seeds it contains in a quadratic regression, with the highest seed count occurring when the capsule length is approximately 25–30 mm White vein on leaves was a dominant trait controlled by a single gene pair (V/v), with veinlet veination type (Vl_) assumed to be dominant over or co-dominant with lateral veination type (vlvl). Cleft leaf exhibited incomplete dominance, with deeply cleft (CC) > shallow cleft (Cc) > entire (cc). Crenated leaf margins were dominant (Cr_). Cyanic leaves were suggested to be a polygenic dominant trait with varying expression patterns and frequencies among offspring. Cyanic corolla tubes and lobes were dominant, but these traits were independently inherited, presumably regulated by genes T and W, respectively. Cyanic corollas were categorized into purple, purple-red, and pink. Progeny from intra-color crosses exhibited the same color, while inter-color progeny showed blended coloration, suggesting co-dominance or incomplete dominance. Yellow spots in the corolla tube were inherited as an incompletely dominant trait with the order: deep yellow (YsYs) > shallow yellow (Ysys) > no spot (ysys). Corolla vein patterns were dominant, possibly controlled by a single gene pair (S/s), with S_ indicating presence of veining. When the parental corolla lengths differ, the corolla length of the progeny tends to fall between those of the parents or slightly lean toward the parent with the longer corolla. Fresh pollen of P. liujiangensis, P. longzhouensis, P. ningmingensis, and P. sinovietnamica was cultured at 5–45°C to estimate cardinal temperatures for germination. To was highest for P. liujiangensis (26.22°C) and lowest for P. sinovietnamica (20.43°C). Tm were similar for P. liujiangensis and P. longzhouensis, and lowest for P. sinovietnamica. Under 35/30°C cultivation, Fv/Fm was significantly reduced in P. ningmingensis and P. sinovietnamica. In a 51°C water bath treatment, RI values of all species except P. sinovietnamica declined significantly. P. hochiensis, P. liujiangensis, and their selected hybrid progeny were cultivated at 25/20°C, 30/25°C, and 35/30°C. Under 35/30°C, both P. hochiensis and the progeny displayed reduced plant size. New leaf areas of parents and progeny were reduced under 35/30°C. Fv/Fm values were significantly lower in P. hochiensis and the progeny under high temperature, though progeny performed better than P. hochiensis. The midpoint temperature of RI curve increased with cultivation temperature. Under 35/30°C, both midpoint temperature and corresponding RI values of the progeny were intermediate between parents. Based on morphological traits, four hybrid lines, with white veins or cleft leaves, high floral production, unique floral coloration or anthocyanin pigmentation, and compact plant size suitable for 9 cm pots, were selected from interspecific crosses. A preliminary method for evaluating heat tolerance in Primulina was established based on pollen germination and physiological indicators.