| A specific low cellulose mutant, temporarily named LCM527-1, was obtained by treating the Indica rice527with400Gy60Coγ irradiation. In comparison with527(WT), we performed a preliminary research and analysis on biological characteristics, physicochemical properties, cellular feature, genetic analysis and gene mapping of the mutant LCM527-1. The experiment results as follows:1. We investigated both tested materials on dynamic growth situation, agronomic traits, rice quality properties, breaking-resistance and lodging-resistance. The result indicated that mutant LCM527-1exhibited the weaker growth potential and shorter plant weight in the field. In the process of mutant development, its culm, leaf, sheath and spike branch showed fragility, which gives rise to weaker breaking-resistant strength and low lodging-resistance index. Agronomic traits of mutant LCM527-1displayed reduction of mechanical strength, smaller panicle, low seed setting percentage and total grain number of per panicle. But1000-grain weight and grain density do have no significant difference on both types as well as the rice quality property investigation. In conclusion, mutant LCM527-1with obvious low lodging-resistance exerts vital negative effect on the rice vegetative and reproductive growth due to the mutation gene.2. Analysis of physicochemical properties between mutant LCM527-1and wild type, we found some changes of the chemical components that involved in assembling the cell wall at five development stages. Compared with the wild type, LCM527-1showed significant decrease of cellulose, which played a critical role in constructing cell wall of plant. While hemicellulose and lignin happened to increase in the mutant LCM527-1. Mineral elements investigation displayed Ca, K, Mn, Na, Si and Zn reduced,among them three elements:Ca, K and Si that help to thicken the stalk were also decreased significantly. From above results, it could be concluded that cellulose, as the primary component of the cell wall, played a pivotal role in assembling and functioning, whose large reduction contributed to the thinning of cell wall, weakening combination with hemicellulose and lignin, and thus the fragility occurence in rice. The decreased content of mineral elements indicated absorption and accumulation in mineral elements became lower than the WT, and influenced the machinery strength of wall. These changes of chemical components were probably controlled by the mutation gene, affected basal internode characteristics and caused lower lodging-resistance.3. Under the light microscope, mutant LCM527-1presented the normal cell structure as the wild type. However, the thickness of sclerenchyma cell, especially the upper and lower surfaces of vascular bundle became far thinner, the cell layers decreased and cell lumens extended. While the wild type kept the normal cellular structure. Ultra-structural features were further explaining the different thickness of scler-enchyma and parenchyma cell wall’s structure between WT and mutant LCM527-1. Cell structural changes possibly came from the changes of chemical elements, influenced the normal functions, finally lead to external characteristics difference.4. Four crosses between mutant LCM527-1(female parent) and the wild-type572, Zhehui7954,9311, Minghui63(male parents) were made to study the molecular inheritance pattern of the mutation. Genetic analysis indicated that the mutant phenotype is controlled by a single recessive gene by investigating the phenotype of the F2population and statistically calculating the segregation ratio of3:1from normal:mutant. Mutant gene lcm527-1was mapped on chromosome2between SSR marker RM3774and RM1092with a distance of10.6cM and5.1cM. This gene produced obvious morphological and physiochemical properties, will be of great help to fine mapping and molecular research of lodging resistance in the future. |
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