In wheat, 25 Rht genes for dwarfness are known, which include both, GA-insensitive and GA-responsive genes. The GA-insensitive Rht genes have been widely used, although, their suitability under abiotic stress conditions has been questioned. This necessitated a search for alternative GA-responsive, spontaneous and induced dwarfing genes. We earlier reported an induced dwarf mutant (‘dwarf mutant-3′; 44 cm), and the mutant allele was named Rht4c allele (2BL). This dwarf mutant was not suitable for cultivation due to its extra dwarf nature. Therefore, we searched for naturally occurring QTLs, which would modify the phenotype of ‘dwarf-mutant-3′ using ‘mutant-assisted gene identification and characterization’ (MAGIC) approach. For this purpose, the ‘dwarf mutant-3′ was crossed with a tall wheat cv. NP114 and homozygous mutant F₂ plants (~ 25% of the progeny) were selected, which were phenotyped for plant height and genotyped using SSR markers. The data were utilized for QTL analysis and plant height. Six modifier QTLs were identified on chromosomes 2A, 2B and 4A. Two QTLs each on 2A and 2B were responsible for increase in plant height (described as ‘enhancer modifiers’), whereas the remaining two QTLs located on 4A were responsible for reducing the plant height (described as ‘suppressor modifiers’). It was hypothesized that the enhancer QTLs could be exploited for the development of semi-dwarf high yielding genotypes containing Rht4c allele. This is the first study of its kind in wheat demontsrating that the MAGIC approach could be used for identification of modifiers of the mutant phenotypes of other traits for wheat improvement.

在小麦中，已知有 25 个导致矮化的 Rht 基因，其中包括 GA 不敏感基因和 GA 响应基因。GA 不敏感的 Rht 基因已被广泛使用，但它们在非生物胁迫条件下的适用性受到质疑。这需要寻找替代的 GA 响应性、自发性和诱导性矮化基因。我们早些时候报道了一个诱导的矮突变体（'dwarf突变体-3'；44厘米），突变体等位基因被命名为Rht4c等位基因（2BL）。由于其额外的矮化性质，这种矮化突变体不适合培养。因此，我们搜寻了天然存在的QTL，其中将修改“矮化突变体-3'使用”的表型米utant-一个ssisted克烯我dentification和Ç字符化（MAGIC）方法。为此，将“矮突变体-3”与高小麦品种杂交。选择 NP114 和纯合突变 F ₂植物（约 25% 的后代），对植物高度进行表型分析并使用 SSR 标记进行基因分型。数据用于QTL分析和植物高度。在染色体 2A、2B 和 4A 上鉴定了 6 个修饰 QTL。2A 和 2B 上的两个 QTL 分别负责增加株高（称为“增强子修饰符”），而位于 4A 上的其余两个 QTL 负责降低株高（称为“抑制子修饰符”）。假设可以利用增强子 QTL 开发含有Rht4c的半矮化高产基因型等位基因。这是首次在小麦中进行此类研究，表明 MAGIC 方法可用于鉴定小麦改良其他性状突变表型的修饰物。