Fine-Mapping and Identification of a Candidate Gene Underlying thed2Dwarfing Phenotype in Pearl Millet,Cenchrus americanus(L.) Morrone

Abstract

Pearl millet is one of the most important subsistence crops grown in India and sub-Saharan Africa. In many cereal crops, reduced height is a key trait for enhancing yield, and dwarf mutants have been extensively used in breeding to reduce yield loss due to lodging under intense management. In pearl millet, the recessive d2 dwarfing gene has been deployed widely in commercial germplasm grown in India, the United States, and Australia. Despite its importance, very little research has gone into determining the identity of the d2 gene. We used comparative information, genetic mapping in two F2 populations representing a total of some 1500 progeny, and haplotype analysis of three tall and three dwarf inbred lines to delineate the d2 region by two genetic markers that, in sorghum, define a region of 410 kb with 40 annotated genes. One of the sorghum genes annotated within this region is ABCB1, which encodes a P-glycoprotein involved in auxin transport. This gene had previously been shown to underlie the economically important dw3 dwarf mutation in sorghum. The cosegregation of ABCB1 with the d2 phenotype, its differential expression in the tall inbred ICMP 451 and the dwarf inbred Tift 23DB, and the similar phenotype of stacked lower internodes in the sorghum dw3 and pearl millet d2 mutants suggest that ABCB1 is a likely candidate for d2.

Development of a High‐Density Linkage Map and Tagging Leaf Spot Resistance in Pearl Millet Using Genotyping‐by‐Sequencing Markers

“…The parents of this mapping population, Tift 99D 2 B 1 and Tift 454, are dwarf, early‐maturing grain types. Both parents carry the recessive dwarfing gene d 2 , which lies on LG 4 (Parvathaneni et al, 2013). We discovered very few markers on LG 4 compared to other LGs.…”

Status of Global Pearl Millet Breeding Programs and the Way Forward

“…Burton and Fortson (1966) found that the F 1 of the hybrid between the normal and dwarf genotypes was as tall as the normal inbred parent. The recessive dwarfing gene d 2 has been deployed widely in commercial cultivars grown in Australia, India, and the United States (Parvathaneni et al, 2013). Most of the semidwarf parental lines used in the development of US hybrid forage cultivars were developed using the d 2 gene (Hanna et al, 1997).…”

Perennial Grain and Oilseed Crops

“…Many traits are controlled by a few genes of large effect and can be improved efficiently in perennial grain crops once the relevant genes are identified, as there are many known orthologous genes from other species. For example, shattering is controlled by qSH1 in rice (81), SH1 in sorghum, rice, and maize (86), and qPDH1 in soybean (44); plant height is controlled by Rht-1 in wheat (101), GA20ox-2 in rice and barley (6,67), and dw3 or d2 in sorghum and pearl millet (95,100); grain size is controlled by GS3 in corn and GS3 and GS5 in rice (83,84,88); threshing ability is controlled by Q and Nud (39,131); flowering time is controlled by VRN1 in barley, wheat, and ryegrass (7); grain weight is controlled by GW2 in rice (82), wheat, and corn (83,118,127,129); and glutinous grains are controlled by GBSSI or Waxy in rice, wheat, corn, foxtail millet, barley, and sorghum (78). Many domestication and improvement traits are conferred by mutations in regulatory genes, such as transcription factors (92), which likely accounts for their large phenotypic effects.…”