Phenotypic Identification and Fine-Mapping of the Rice Narrow-Leaf Mutant nal25.

Area of Science:

• Plant genetics and breeding
• Crop science
• Molecular biology

Background:

• Leaf morphology is crucial for rice (Oryza sativa L.) plant architecture and yield.
• Understanding genetic factors controlling leaf shape is key to crop improvement.

Purpose of the Study:

• To identify and characterize a novel narrow-leaf mutant in rice.
• To elucidate the genetic basis of the narrow-leaf phenotype and its impact on yield traits.

Main Methods:

• EMS mutagenesis was used to generate mutants from the indica rice cultivar 'Huazhan'.
• Phenotypic analysis, genetic mapping, gene sequencing, and qRT-PCR were employed to characterize the mutant and gene.
• Precise localization identified the candidate gene on rice chromosome 7.

Main Results:

• A narrow-leaf mutant, nal25, was identified with reduced plant height, increased tillering, and decreased grain size and seed setting rate.
• The narrow-leaf phenotype is controlled by a single recessive nuclear gene, NAL25.
• A T-to-C mutation in the heat-shock protein gene LOC_Os07g09450 (encoding a DnaJ domain) was identified as the cause of the mutation, leading to an amino acid change from leucine to proline.

Conclusions:

• The nal25 mutant exhibits dwarfism and excessive tillering, offering valuable genetic resources for forward genetics.
• This research contributes to understanding leaf morphology's role in rice plant architecture and yield.
• The findings support the development of improved rice varieties for stable yield increases and global food security.