Recurrent selection for increased outcrossing rates in caudatum-race sorghum from Sudan

高粱（Sorbicolor）是生活在非洲苏丹-萨赫勒地区半干旱地区的大多数人的主食，但平均谷物产量低且多变。已发表的研究实验结果表明，高粱杂交种可能显示出相当大的杂种优势，特别是在粮食产量方面。然而，杂交育种目前对大多数苏丹高粱种植区来说不是一个经济的选择。培育异交率大幅提高的人工合成品种被认为是提高产量和抗逆性的一种有前途的选择。在苏丹流行的尾状人种中，异交率约为16%，取决于人种、基因型和环境。在我们的项目中，我们希望通过使用分子标记的轮回选择（RS）来提高远交水平。高度杂合的植物最有可能是由异交产生的，并且可能携带有具有高度异交能力的亲本基因。这些植物将在开花前被选择并移植到花粉隔离杂交区，用于新的RS周期。我们预计在项目阶段可以完成四个RS周期，每个RS周期的平均异交率增加约0.05。该项目的基础群体将由来自苏丹的约100个尾状核小种品种组成。将在该国主要种植区进行的最后一次多地点田间试验中对选择的收益进行评估。

Sorghum (Sorghum bicolor) is a staple food for the majority of people living in the semi-arid areas of the Sudanian-Sahelian zone of Africa but average grain yields are low and variable. Results of published research experiments have demonstrated that sorghum hybrids may display considerable heterosis particularly for grain yield. However, hybrid breeding is not an economic option for most Sudanese sorghum growing areas at present. Developing synthetic varieties with a substantially raised outcrossing rate is considered a promising alternative to enhance yield and stress tolerance. In the caudatum race which prevails in Sudan, the outcrossing rate varies around 16% depending on race, genotype and environment. In our project we want to increase the outbreeding level by recurrent selection (RS) employing molecular markers. Highly heterozygous plants are most likely to have arisen from outcrossing and are likely to carry parental genes for high outcrossing aptitude. Such plants will be selected before flowering and transplanted to a pollen isolated crossing plot for starling a new RS cycle. We expect that four RS cycles can be completed during the project phase with an increase of the average outcrossing rate of about 0.05 per RS cycle. The base population for this project will be composed of about 100 caudatum race cultivars from Sudan. The gain from selection will be assessed in a final multi-location field experiment in the major growing areas of the country.