Plant Gene and Trait 2024, Vol.15, No.2, 73-84 http://genbreedpublisher.com/index.php/pgt 74 This study delves into the specific impact of the DEP1 gene on rice panicle architecture and yield. By employing molecular biology techniques, we elucidate the functional mechanisms of the DEP1 gene, clarifying its role and regulatory network in the development of rice panicles. Additionally, we assess the practical effects of DEP1 gene variation on panicle morphology and yield, providing scientific basis and technical support for rice molecular breeding, thereby promoting further enhancement of rice yield. 2DEP1 Gene: Functions and Mechanisms 2.1 Discovery and characterization of the DEP1 gene The DEP1 locus was identified as a major quantitative trait locus (QTL) influencing grain yield through the modulation of panicle architecture. The dominant allele at the DEP1 locus is a gain-of-function mutation that results in the truncation of a phosphatidylethanolamine-binding protein-like domain protein. This mutation enhances meristematic activity, leading to a reduced length of the inflorescence internode, an increased number of grains per panicle, and consequently, a higher grain yield. This allele is prevalent in many high-yielding Chinese rice varieties and is believed to have been introduced relatively recently into the cultivated rice gene pool (Huang et al., 2009). Further studies have shown that the DEP1 gene is highly expressed in young tissues, particularly in young panicles, indicating its crucial role during the early stages of panicle development. The mutation in DEP1 primarily affects the rapid elongation of the rachis and primary and secondary branches, without impairing the initiation or formation of panicle primordia. This results in a more compact plant type, which is advantageous for achieving higher yields without significant alterations in grain production (Li et al., 2010). The DEP1 gene’s role extends beyond individual plant yield to population-level improvements. The erect panicle architecture conferred by the DEP1 allele optimizes canopy structure, allowing more light to penetrate the lower leaves, thereby enhancing photosynthetic efficiency and biomass accumulation. This trait also enables higher planting densities and better resource utilization, contributing to sustainable agricultural practices (Fei et al., 2019). 2.2 Molecular mechanisms: howDEP1 affects panicle development The DENSE AND ERECT PANICLE 1 (DEP1) gene plays a crucial role in determining the architecture of the rice panicle, which directly impacts grain yield. DEP1 encodes a protein with a phosphatidylethanolamine-binding protein-like domain, and a gain-of-function mutation in this gene results in a truncated protein that enhances meristematic activity. This increased activity leads to a reduced length of the inflorescence internode, an increased number of grains per panicle, and consequently, a higher grain yield (Huang et al., 2009). Additionally, DEP1 is involved in regulating the carbon-nitrogen metabolic balance, which affects grain yield and quality. Overexpression of DEP1 enhances nitrogen uptake and assimilation, although it disrupts the carbon-nitrogen balance, leading to increased grain numbers per panicle but decreased grain quality (Zhao et al., 2019). The DEP1 gene also interacts with the G protein signaling pathway, influencing various physiological and morphological functions, including nitrogen uptake and stress tolerance (Xu et al., 2016). 2.3 Variants of DEP1 and their impacts on rice phenotypes Several variants of the DEP1 gene have been identified, each with distinct impacts on rice phenotypes. The dominant allele of DEP1, which is a gain-of-function mutation, is common in many high-yielding Chinese rice varieties and has been shown to enhance grain yield by increasing the number of grains per panicle (Huang et al., 2009). Another study identified a novel dense and erect panicle (EP) mutant, dep3, which is controlled by a single recessive gene. The dep3 mutant exhibits a denser and more erect panicle architecture, with more small vascular bundles and a thicker culm, contributing to its unique phenotype (Qiao et al., 2011). Furthermore, the DEP1 gene has been linked to improved nitrogen use efficiency and lodging tolerance, making it a valuable target for rice breeding programs aimed at developing high-yielding and stress-tolerant varieties (Xu et al., 2016). The DEP2 gene, another variant affecting panicle architecture, primarily influences the elongation of
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