Study of dwarfing wheat sources using near isogenic lines

chinois. 开拓小麦育种新矮源，克服自小麦矮化育种“绿色革命”以来，仅使用Rht1、Rht2、Rht8等少数几个隐性矮源的局限性，为选育高度集约化的小麦新品种提供条件。将国内外已定名的5个显性矮源Rht10、Rht3、Rht12、Rht21、奥尔森矮（Olesen dwarf）和西南大学农学与生物科技学院培育与征集的7个致矮力弱的显性矮源回交导入4个中、高秆（85～105 cm）轮回父本品种（BC4F1），建立了4套矮秆基因的近等基因系。2005～2006两年，在非竞争群体条件下开展了近等基因系的多因素品系比较试验，研究矮源及轮回父本遗传背景两个主因素对近等基因系主要农艺性状的影响效应。12个显性矮源在本试验统一遗传背景条件下株高为37.9～74.3 cm，显性矮源的株高与其株粒重呈高度正相关（r=0.8884），株高每上升1 cm，则株粒重增加0.24 g。随显性矮源株高的提升、致矮力减弱，其近等基因系的农艺性状得到改善。显性矮源的株高提升到60 cm以上时，即有可能达到和超过中、高秆轮回父本的单株生产力，从而作为新型矮源应用于小麦矮化育种。此外，12个显性矮源具有一致的延迟早熟轮回父本抽穗以及降低轮回父本千粒重的多效性效应，这些不利的多效性效应可以通过轮回父本遗传背景的修饰作用加以改良。株高在50 cm以下的强致矮力显性矮源，难以直接用于小麦育种，但通过矮秆主基因突变以及特殊遗传背景的修饰等途径可以衍生出株高呈不同程度提升、以致达到70～80 cm理想株高的弱致矮力显性矮源。加强株高提升的弱致矮力显性矮源的研究是将显性矮源应用于小麦杂交育种的有效途径。推荐株高在60～75 cm的弱致矮力显性矮源SW07、SW05、女水妖矮、SW02、Rht21用于小麦矮化育种。

anglais. Since the “green revolution” in the middle 20th century, in which wheat breeding was focused on dwarfing, wheat breeding in various countries of the world has been confined to a limited number of recessive dwarfing sources such as Rht1, Rht2 and Rht8. This study is intended to broaden the dwarfing sources of wheat so as to help the development of highly intensive varieties in wheat cultivation. Five known dominant dwarfing source genes(Rht3, Rht10, Rht12, Rht21 and Olesen) and 7 dominant dwarfing sources with moderate dwarfing ability developed and selected by the Wheat Breeding Laboratory of Southwest University (China), were incorporated into 4 mediums or tall-statured wheat varieties (F1B4 recurrent paternal parents) through back-crossing, thus establishing 4 sets of near isogenic lines of dwarfing genes. In 2005-2006, a multi-factor comparative experiment was conducted under non-competitive conditions of these near isogenic lines to investigate the effects of the genetic backgrounds of the drawfing genes and the recurrent paternal parents on the major agronomic characters. Under the unified genetic backgrounds of the present study, the plant height of all the 12 dwarfing sources ranged from 37.9～74.3cm, being in a significant correlation with their grain weight per plant (r=0.8884). Their grain weight per plant increased by 0.24 g as plant height increased by 1 cm. The agronomic characters of the NILs improved rapidly as their plant height increased and their dwarfing effect weakened. The productivity of a dwarfing source variety approached or exceeded its medium or tall-statured recurrent parent when its plant height was raised to 60 cm or more. It, therefore, is possible to use such innovative dwarfing sources directly in hybridization breeding of wheat. In addition to such major effects, the 12 dwarfing genes showed pleiotropic effects of delaying the heading of the paternal recurrent parents and reducing their 1000-seed-weight, which, however, can be overcome by modifying the genetic backgrounds of the recurrent paternal parent. The experiment provides additional evidence that dwarfing source varieties with a plant height of 50 cm or less, with their high dwarfing effect, can hardly be employed directly in wheat breading due to their low biomass production; however, their plant height can be increased, to different extents, and some weak dwarfing source varieties may have an ideal plant height of 70-80 cm. This can be conducted through mutation of the major dwarfing gene(s) or the modification by special genetic background. Strengthening the research of weak dwarfing sources with increased plant height is a fundamental approach in application of dominant dwarfing sources in wheat hybridization breeding. It is recommended that the dominant weak dwarfing sources developed and selected in this study, i.e. SW07, SW05, YD Ai, SW02 and Rht21be utilized in “gene-designed” dwarfing breeding of wheat.