阔叶野生稻黎明开花特性的转育和栽培稻早晨开花系的研究

 采用栽培稻核质互作雄性不育系(O.sativa, 2n=24=AA)为母本、阔叶野生稻(O.latifolia, 2n=4x=48=CCDD)为父本,不经幼胚组培挽救环节直接获得杂种一代种子和植株并在此基础上多次回交与自交选择的常规野栽交转育方法,已将阔叶野生稻的黎明开花基因转入栽培稻,育成的栽培稻早晨开花材料连续3代(F₃～F₅)均只分离出早晨与中午两次开花的新类型和只在中午开花的正常类型等两种类型,未见早晨开花而中午不开花的新类型,早晨开花类型为24%～37%,比例相对稳定。(1)本研究获得的早晨开花材料花时的特点: 早晨和中午两次开花,两次开花不重复、等量和集中,早晨开花盛期在上午9∶30左右,早晨开花的气候稳定性好于正常的中午开花和野生稻的黎明开花,而中午开花正常;(2)获得的早晨开花材料中早晨和中午均开花的新类型和只在中午开花的正常类型在穗长、着粒密度、结实率、千粒重、糙米色、闭颖状况等方面存在明显差异,早晨开花的新类型生产性能明显不如只在中午开花的正常类型;(3)本研究染色体组间异源基因常规转育十分艰难, BC₁F₁和之前世代的回交结实极低,小于1%,BC₁F₂世代虽然回交结实达到1.0%～9.8%,且早晨开花性状也表现明显和集中,但早晨开花性状在继续选育过程中极易丢失,BC₁F₂之后世代早晨开花材料才稳定地分离出早晨开花和只在中午开花两种类型;(4)讨论了育种可用的早晨开花的标准,即在正常天气条件下早晨9∶00～10∶00自然盛花为育种可用的早晨开花特性;(5)远缘野栽交基因转育用不育系作母本容易获得F₁种子, F₀种子播种成苗率因组合而异,为1.5%～10%,说明获得F₁植株仍然较难.

Intergenomic Gene Transferring for Early-morning Flowering from O.latifolia to O.sativa by Common Hybridization Method and Studying on the Early-morning Flowering Lines of O.sativa with the Monosomic Alien Addition of O.latifolia

Several crosses of Oryza sativa×O.latifolia were made by using male sterile lines as female parents. The F₁ hybrids plant were obtained successfully without embryo culture. On the basis of F₁ hybrids plant, the Early-morning flowering gene was transferred successfully from O.latifolia to O.sativa by backcrossing successively to O.sativa and selecting. The Early-morning flowering lines have two segregation types of plants, one with Early-morning flowering traits and another without.The Early-morning flowering plants in the Early-morning flowering lines flowers both at early-morning and noon. The plants flowering only at Early-morning and not at noon in the Early-morning flowering lines was not observed. The inheritance transmission rates for Early-morning flowering traits in the Early-morning flowering lines are relatively stable from generation to generation and is 24%~37% from F₃ to F₅. (1)The flowering time character of the Early-morning flowering plants in the Early-morning flowering lines flowers always both at about 9∶30 in the early morning and noon for the spikelets in different location and equally to each other for numbers;The stability of the flowering at early morning for Early-morning flowering lines over climate is noticeably much better than that of both the flowering at noon for normal cultivars and the the flowering at early morning for the wild rice O.latifolia. The stability of the flowering at noon for Early-morning flowering lines over climate is the same as that of the flowering at noon for normal cultivars. (2)There are obvious differences in spike length,grain density,seed setting,1000-grain weight,brown rice color and the glume-closing much degree between the plants flowering at Early-morning and the plants flowering only at noon in the Early-morning flowering lines and the productivity of the former is obviously lower than that of the latter. (3)This intergenomic gene transferring was very difficulty by conventional hybridization, for the backcrossing seed setting of BC₁F₁ and before generations was very low and lower than 1% normally, though the backcrossing setting of the plant flowering at early morning in the Early-morning lines for the BC₁F₂ generation reaches 1.0%~9.8% and flowers noticeably at early morning and centralizes over time but the Early-morning flowering trait is very easy to be lost in the course of selecting till F₃～F₅ generations the Early-morning flowering lines segregates stably two types plants of flowering at early-morning and flowering only at noon. (4)The criterion of flowering at early-morning trait available for rice breeding was discussed,namely,the Early-morning flowering traits available for rice breeding is ones flowering numerously at 9∶00～10∶00 under normal climate condition. (5)Through it is easy to get F₀ seeds by using male sterile lines as female parents in interspecific gene transferring from distantly related wild species to cultivar ones but it is still very difficult to get F₁ plants because seedling emergence percentage of F₀ seeds was only 1.5%～10% and differs noticeably among combinations.