Abstract
Grain shape is one of the most important and complex traits determining the grain yield in rice. In this study, we discovered two rice mutants with defective shape spikelets, designated as psh1-1/2 (pepper-shaped husk 1-1/2), which were both isolated from the tissue-culture-regenerated plants of indica cultivar Minghui 86. The two mutants showed the same mutant phenotypes, containing pepper-shaped spikelets; shorter, smaller and compact panicles; very low seed-setting rate; high percentage of split grains; and lower grain width. Genetic analysis indicated that the mutant phenotypes were controlled by a recessive gene. Gene mapping indicated that the target gene PSH1 was located on the short arm of chromosome 4. Sequencing analysis revealed that the two mutants each had a different nonsense mutation in OsARG, confirming that the target gene is OsARG. Compared with the previously reported OsARG mutant nglf-1, psh1-1/2 possessed some distinct mutant phenotypes, probably because of the influence of different genetic background, suggesting that OsARG may function differently under different genetic backgrounds.
Highlights
Rice is one of the most important food crops for more than half of the global population.Breeding ideal superior rice cultivars with improved grain shape and other agronomic traits, such as nutritional value, disease resistance, and stress tolerance, has been the goal of rice breeders for a long time
GS3, which encodes a transmembrane protein consisting of four putative domains, was the first cloned QTL controlling grain length [5]. qGL3, encoding a putative protein phosphatase with a Kelch-like repeat domain, regulates grain length [6]
The rice psh1 mutant was obtained from the progeny of tissue culture of the rice (Oryza sativa L. ssp. indica) cultivar Minghui 86 (MH86)
Summary
Rice is one of the most important food crops for more than half of the global population. Some genes involved in panicle development in rice, such as SP1 [15], qPE9-1 [16], EP2 [17], DEP2 [18], and DEP3 [19], can affect grain size or shape, too. LHS1/OsAMDS1 has a redundant role with MFO1 in palea identity specification by promoting MRP development [25,28] Besides these genes specific effects on palea development, there are many other genes conferring both palea and lemma development, such as OPB [29], DH1 [30], SHO1 [31], SHL2 [32], SHL4 [32], WAF1 [33], TH1 [34], and BH1 [35]. This work allowed us to further uncover the function of OsARG in regulating flower shape and spikelet fertility
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