A substitution mutation in OsCCD7 cosegregates with dwarf and increased tillering phenotype in rice

Abstract

Dwarf plant height and tillering ability are two of the most important agronomic traits that determine the plant architecture, and have profound influence on grain yield in rice. To understand the molecular mechanism controlling these two traits, an EMS-induced recessive dwarf and increased tillering1 (dit1) mutant was characterized. The mutant showed proportionate reduction in each internode as compared to wild type revealing that it belonged to the category of dn-type of dwarf mutants. Besides, exogenous application of GA3 and 24-epibrassinolide, did not have any effect on the phenotype of the mutant. The gene was mapped on the long arm of chromosome 4, identified through positional candidate approach and verified by cosegregation analysis. It was found to encode carotenoid cleavage dioxygenase7 (CCD7) and identified as an allele of htd1. The mutant carried substitution of two nucleotides CC to AA in the sixth exon of the gene that resulted in substitution of serine by a stop codon in the mutant, and thus formation of a truncated protein, unlike amino acid substitution event in htd1. The new allele will facilitate further functional characterization of this gene, which may lead to unfolding of newer signalling pathways involving plant development and architecture.

Comparing Hydroponics, Sand, and Soil Medium To Evaluate Contrasting Rice Nagina 22 Mutants for Tolerance to Phosphorus Deficiency

“…Nagina 22 is a well-known aus variety used routinely as a check for heat tolerance in rice (Jagadish et al, 2010). In a network project, EMS-induced stabilized N22 mutants were evaluated for different traits, such as tolerance to herbicide, heat, low P, water deficiency, and salinity and resistance to bacterial leaf blight and blast (Kulkarni et al, 2013(Kulkarni et al, , 2014Lima et al, 2015;Mithra et al, 2016;Mohapatra et al, 2014;Panigrahy et al, 2009Panigrahy et al, , 2011Panigrahy et al, , 2014Poli et al, 2013;Talla et al, 2016). As a part of the network project on functional genomics, a total of 2500 N22 mutants were screened at the Indian Institute of Rice Research (IIRR) under field conditions maintained with low P (Olsen P, <1.8) to identify low-P-tolerant and susceptible mutants.…”

Fine Mapping and Candidate Gene Analysis of the Tiller Suppression Gene ts1 in Rice

“…In spite of these, however, mapping of dit1 appears to suggest that to develop advanced segregating populations such as NILs or CSSLs is not always prerequisite for fine mapping of the genes underlying such a quantitative trait. In the mapping case of the EMS-induced dit1 allele for dwarf and increased tillering, the gene on chromosome 4 could explain 19.79% of tiller number variation in its F2 mapping population [14]. In this study, trait culm number was also found to show a continuous distribution in the ts1 /Wushansimiao F2 population.…”

“…In rice, tillering has been found to be quantitative in nature [14]. Tiller number trait tends to show a continuous distribution in a segregated population, which indicates that multiple genes or QTLs could be involved in its regulation.…”

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“…4A). Mutants of Loc_Os06g46470, including hdt1 and osccd7, exhibited similar phenotype with so1 (Kulkarni et al 2014;Zou et al 2006), we therefore concluded that the so1 phenotype is due to the 8bp insertion in Loc_Os04g46470.…”

“…HTD1 encodes a carotenoid cleavage dioxygenase involved in SL synthesis, which negatively regulates the growth of axillary buds (Kulkarni et al 2014;Zou et al 2006). However, whether and how HDT1 functions in other tissues was unknown.…”