棉花光敏雄性不育基因的精细定位和候选基因的克隆

Cotton is an important economic crop in China and has strong heterosis. The current methods of hybrid seeds production, hand emasculation-pollination or genetic male sterile techniques, need a large number of labor force, which make the hybrid seeds more expensive and restrict the utilization of hybrid seeds in cotton. Therefore, creating suitable sterile lines in cotton for the production of cotton hybrid seeds is an effective way for reducing the cost of cotton hybrid seeds production and achieving high effectiveness. IN our previous research, a photosensitive genetic male sterile (PGMS) cotton line CCRI9106 was screened out from space mutation seeds. Using CCRI9106, We can produce hybrid seeds under the long-day condition areas with CCRI9106 sterile characteristic. Moreover, CCRI9106 sterile characteristic allows CCRI9106 self-multiplication under short-day condition areas. The cultivation of CCRI9106 is not only important to the application of cotton heterosis, but it is also important to launch studies on the cotton photosensitive genetic male sterile mechanism. In order to use CCRI9106 to launch studies on cotton photosensitive genetic male sterile mechanism, the first thing to do is cloning the photosensitive genetic male sterile gene. The best way to perform such cloning is by using map-based cloning. For map-based cloning, fine mapping of the target gene is the prerequisite. Therefore, this study will mainly focus on fine mapping and cloning the photosensitive genetic male sterile gene in 9106, which final purpose is to obtain the candidate target genes to do further researches on the mechanism of cotton photosensitive genetic male sterile.

棉花是我国重要的经济作物，有明显的杂种优势。现有的人工去雄和“三系”等制种方法成本高、效率低，是棉花杂交种推广及应用的瓶颈，选育合适的雄性不育系是解决此问题的有效途径。前期研究中，我们通过航空诱变选育到了长日照不育、短日照可育的棉花光敏雄性不育系中9106。利用中9106可在长日照地区配制杂交组合，在短日照地区繁殖不育系。中9106的成功选育不仅对推进棉花杂种优势利用具有重要意义，对棉花光敏不育机理的研究也有重要意义。利用中9106研究棉花光敏雄性不育机理的前提是克隆该光敏雄性不育基因。基因克隆的首选方法是图位克隆，图位克隆的首要条件是精细定位目标基因。因此，本研究将主要围绕中9106光敏雄性不育基因的精细定位及克隆开展工作，其主要目的是获得中9106中光敏雄性不育基因的候选基因，为利用该基因进行棉花光敏雄性不育机理研究奠定基础。

光温敏雄性不育系是指育性受光照和温度条件调控的核不育系。利用光温敏不育系配制杂交种，可以简化杂交育种和制种程序，降低杂交种生产成本。本研究所用材料为通过航天诱变育种获得的具有淡绿标记的新型棉花光敏雄性不育突变体中9106，主要围绕中9106表型特性和光敏不育基因的精细定位展开工作。中9106是幼嫩叶片带有淡绿标记的光敏雄性不育系，并且长势较缓慢。本研究发现，各个时期中9106叶片的叶绿素a、叶绿素b和类胡萝卜素含量较其野生型都出现了一定程度的降低，但差异程度不大，这与两者叶色差别程度相对应，因此可以推测中9106叶色的变化可能是由于叶片中叶绿素含量的变化造成的。另外，中9106倒1、倒3叶的类囊体排列存在缺陷，表现为不规则，且类囊体数目较少，中9106叶绿体中的淀粉粒也明显小于其野生型，表明中9106的叶绿体在淀粉制造方面也存在一定的缺陷。前期研究结果已经表明中9106的光敏不育性状受一对隐性基因控制。本研究中利用3个F2群体对中9106的光敏不育基因进行了精细定位，候选区域内得到237个基因。而后，基于转录组数据对候选区域的基因进行了筛选，得到15个表达差异较大的候选基因，并对其中的8个候选基因进行了棉花VIGS实验验证，结果表明 Gh _FLA1、Gh_ CS1、Gh_XG1三个基因的VIGS植株存在大多数花药不开裂和花粉异常的现象，推测上述三个基因可能与中9106的光敏不育性状相关。综上所述，本研究初步探明了中9106光敏不育系叶色变化的原因，同时还通过群体定位、转录组、VIGS等方法的结合，筛选到3个可能与中9106光敏不育性状相关的基因。本研究为以后深入研究棉花光敏雄性不育机理奠定了基础。