【作者】 李晓捷；

【导师】 杨官品；

【作者基本信息】 中国海洋大学 ， 生物化学与分子生物学， 2008， 博士

【摘要】 海带是冷水性大型海藻,自然分布于太平洋和大西洋北部沿海。我国是最大的海带栽培国,从北方的辽宁、山东到南方的江苏、浙江和福建均有大面积栽培。海带遗传育种在海带产业发展中占有举足轻重的地位。我国自二十世纪五十年代开始进行海带遗传改良研究,共培育了约20余个优良品种(系),其推广应用大大促进了海带产业的发展。但是,由于常规生产技术的限制,品种退化、杂合、抗逆性差等问题越来越突出。此外,随着相关产业的快速发展,不同行业对海带品种的需求日益趋向多元化。目前的海带品种已远远不能满足产业发展的需要。杂交海带培育是直接利用配子体克隆杂交获得的子一代进行海上栽培,具有培育周期短、效率高的优点,是实现海带品种快速改良的有效手段,但也存在配组盲目性强、海上评价工作量大的缺点。本论文主要围绕杂交海带的培育与应用进行研究。采用性状差异大且互补的种间配子体克隆杂交培育了东方2号杂交海带,利用介于种间和种内关系之间的配子体克隆为亲本杂交获得了东方3号杂交海带,利用微卫星DNA标记技术建立了海带杂种优势预测方法,并在生产中进行了验证。研究取得以下主要结果:利用长海带(L. longissima)的一个雄配子体克隆和海带(L. japonica)的一个雌配子体克隆经种间杂交获得了具有显著杂种优势的东方2号杂交海带。在烟台芝罘湾对东方2号杂交海带、长海带、海带和两个生产种的性状进行了比较研究,结果表明:东方2号杂交海带产量优势率达56.5%,比长海带和海带分别增产40.8%和76.3%,比两个生产种分别增产35.4%和52.2%;结合较完善的配子体克隆育苗技术在不同海区进行了大面积应用,结果表明:东方2号杂交海带比生产种1平均增产25.6%,比生产种2平均增产61.9%。东方2号杂交海带是我国第一个在生产上大面积应用的杂交海带,其个体整齐宽大、色泽深褐、纵沟明显、根系发达、性状稳定、抗强光能力较强、厚成期适中,产量优势明显,适合不同海区栽培。以LZZ品系(长海带雌配子体克隆与“早厚成一号”雄配子体克隆杂交结合自交选育获得的耐高温、抗强光品系)雄配子体克隆为父本,以海带(L. japonica)改良品系——7号的雌配子体克隆为母本,杂交获得东方3号杂交海带。LZZ品系和7号品系的关系介于种间和种内之间,二者杂交获得的东方3号杂交海带个体宽大,根系发达,基部偏圆,纵沟较明显,藻体韧性强,边缘较普通品种厚、波褶少,叶片上下厚度均匀,色泽深褐。东方3号杂交海带生长速度快、耐高温、脱落轻、抗强光,属于晚厚成品种。荣成褚岛湾连续三年的栽培结果显示东方3号杂交海带较主要生产种对照Ⅰ和对照Ⅱ平均增产54.1%和62.3%,较LZZ品系和7号品系分别增产60.7%和74.1%;在我国北方多海区栽培结果表明:较对照Ⅰ平均增产32.0%,较对照Ⅱ平均增产56.9%。利用微卫星DNA标记技术对27个配子体杂交亲本进行了遗传相似性分析,并对株长、株宽、株厚、株鲜重、株干重、产量杂种优势率与配子体亲本之间的遗传距离进行了回归分析。结果表明:株长、株鲜重、株干重和产量优势率与遗传距离呈显著线性相关关系,而株宽和株厚优势率与遗传距离之间没有显著线性相关关系。回归方程分别为:长度优势率y = 76. 31x?59.911(x为亲本配子体的遗传距离,R~2=0.6498,P<0.0001);鲜重优势率y = 85. 016x-66.497(R~2=0.6603,P<0.0001);干重优势率y = 90. 984x?70.625(R~2=0.6423,P<0.0001);产量优势率y = 90. 984x-70.625(R~2=0.6423,P<0.0001)。利用建立的回归方程结合互补原则对可能产生优势的组合进行了预测和海上性状评价,筛选出三个杂交海带新组合。表明杂种优势预测方法可用于产量及产量相关性状优势预测,结合抗逆性等非数量性状互补原则选择配子体克隆亲本,可减少配组盲目性,实现海上评价组合数的科学减量,提高育种效率。更多还原

【Abstract】 Laminaria is a group of brown macroalgae living in cold seawater and distributing in northern seashore of Pacific and Atlantic naturally. China is the biggest country of Laminaria cultivation. The species cultivated in China on large scale is Laminaria japonica northward to Liaoning and Shandong and southward to Jiangsu,Zhejiang and Fujian.Genetic improvement played a crucial role in the development of Laminaria cultivation of China. Genetic improvement of Laminaria began in 1950s and more than 20 varieties have been bred and used. Their popularization promoted the development of Laminaria cultivation industry drastically. Because the restriction of traditional methods, the problems such as degeneration, heterozygosis and weak stress resistance have become severe and severe. Moreover, with rapid development of the relative industries depending on Laminaria, diverse varieties are appreciated. Laminaria varieties available currently can not satisfy the development of Laminaria depending industry. Fortunately, Laminaria hybrids can be cultivated directly, and the breeding of Laminaria hybrids is relatively fast. However, the selection of Laminaria hybrids is still labor intensive and fortune dependent.This thesis reported our results obtained in breeding and application of hybrid Laminaria. Dongfang No. 2 hybrid Laminaria was developed by interspecific hybridization of gametophyte clones. And Dongfang No. 3 hybrid Laminaria was bred through hybridization of gametophyte clones with a more than intraspecific but less than interspecific relationship. In addition, a method of predicting the heterosis of Laminaria hybrids with the genetic distance between their parental gametophyte clones was established and validated.The following are our major findings:A male gametophyte clone from L. longissima and a female one from L. japonica were hybridized with the filial generation, Dongfang No. 2 hybrid Laminaria, used directly in trial cultivation. This initiated the direct use of Laminaria heterosis in production. The agronomic traits of Dongfang No. 2 hybrid, the source sporophytes from which its parental gametophyte clones were isolated and two commercial varieties widely used currently were compared in Zhifu Bay. Dongfang No. 2 showed 56.5% heterozygous vigor (heterosis) in yield, increasing the yield by 40.8% and 76.3% over that of L. longissima and L. japonica, and by 35.4% and 52.2% over that of commercial Variety 1 and Variety 2. In combination with gametophyte clone based seedling raising method, Dongfang No. 2 was cultivated in large area at different places and in different years. On average, the yield of Dongfang No. 2 was significantly higher than those of two commercial varieties, boosting up the yield by 25.6% in average over that of commercial Variety 1 and by 61.9% over that of another. Dongfang No. 2 hybrid Laminaria is the first hybrid Laminaria which was used in large-scale cultivation in China. It has a robust holdfast and a wide, long and deep brown uniform blade with a very clear groove in blade. In addition, Dongfang No. 2 also holds heterosis in other traits including the tolerance to strong irradiance. The vegetative maturation date of Dongfang No. 2 is moderate. Dongfang No. 2 hybrid Laminaria adapts well to a wide range of culturing environments.Dongfang No. 3, a Laminaria hybrid, was bred by hybridizing a female gametophyte clone isolated from Line 7 of L. japonica with a male one isolated from Line LZZ developed through hybridizing female gametophyte clones of L. longissima and male gametophyte clones of L. japonica followed by continuous self-crossing and tolerances of strong irradiance and high seawater temperature targeted selection. The parental gametophyte clones of Dongfang No. 3 have a more than intraspecific but less than interspecific relationship. The dark brown hybrid has a wide, uniform, ripple-less and very tough blade and a very robust holdfast. A deep vertical groove, a half-round joint between stipe and blade and thick blade edges distinguished the hybrid from other varieties of L. japonica. The hybrid grows faster than other control varieties. It tolerates high irradiance and seawater temperature and resists the tissue rottenness of blade tip and edges. The hybrid matured later than the varieties of L. japonica widely used currently. As were observed in continuous three years in Chudao Bay, Dongfang No. 3 hybrid Laminaria increased the yield by 54.1% and 62.3% in average over that of Control I and Control II, respectively, and by 60.7% and 74.1% over that of Line LZZ and Line 7. Across 10 sites on the coast of north China and in different years, it boosted up the yield by 32.0% and 56.9% in average over that of Control I and II, respectively.Microsatellite DNA markers were used to determine the genetic distances between 27 parental gametophyte clones, which were then regressed to the heterosis (heterozygous vigor) of economic traits including blade length, blade width, mean blade thickness, mean blade fresh weight, mean blade dry weight and yield. Significant regression was established between the genetic distance (x) and the heterosis (y) of blade length ( y = 76. 31x?59.911,R2 =0.6498,P<0.0001), mean blade fresh weight ( y = 85. 016x?66.497,R2 =0.6603,P<0.0001), mean blade dry weight ( y = 90. 984x?70.625,R2 =0.6423,P<0.0001) and yield ( y = 90. 984x? 70 .625,R 2 = 0.6423,P<0.0001). Based on the regression equations established and the complementary hypothesis of non-quantitative characteristics such as stress resistance, a few combinations were predicted to perform high yield and stress tolerance. Such prediction was proved to be true in the trait evaluation of these hybrids conducted subsequently. Our findings have indicated that the method is effective for predicting the heterosis of yield and yield related traits. The method will facilitate the selection of elite Laminaria hybrids by avoiding the time-consuming and labor-intensive field trait evaluation of a large number of hybridization combinations.更多还原