Identification of modifiers of the plant height in wheat using an induced dwarf mutant controlled by RhtB4c allele
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RESEARCH ARTICLE
Identification of modifiers of the plant height in wheat using an induced dwarf mutant controlled by RhtB4c allele Priyanka Agarwal1 • H. S. Balyan1 • P. K. Gupta1
Received: 4 September 2020 / Revised: 29 September 2020 / Accepted: 19 October 2020 Ó Prof. H.S. Srivastava Foundation for Science and Society 2020
Abstract 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-30 ; 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-30 using ‘mutant-assisted gene identification and characterization’ (MAGIC) approach. For this purpose, the ‘dwarf mutant-30 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 & P. K. Gupta [email protected]; [email protected] 1
Department of Genetics and Plant Breeding, Ch. Charan Singh University, Meerut 250004, India
the mutant phenotypes of other traits for wheat improvement. Keywords Rht genes Dwarf mutant Plant height MAGIC (mutant-assisted gene identification and characterization) Modifier QTLs Triticum aestivum L
Introduction In wheat, 25 major dwarfing genes called Rht genes (Rht1Rht25) are known (McIntosh et al. 2017; Mo et al. 2018). Majority of these Rht genes occur in natural populations; some were also obtained using physical/chemical mutagens. The Rht genes are known to be responsible for reduced plant height, lodging resistance, increased tillers, higher harvest index and higher yield (Hedden 2003; Ellis et al. 2005; see Jobson et al. 2019 for references). The most important of these Rht genes, are the two GA-insensitive dwarfing genes, namely Rht1 (RhtB1b) located on chromosome arm 4BS and Rht2 (RhtD1b), located on 4DS. These two genes have similar and additive effect on plant height (see Jobson et al. 2019 for references), and are described as ‘gr
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