Studies On The Regulatory Function Of Rice OsCesA4Gene In Cellulose Synthesis And Fiber Characteristics

Rice lodging is a key issue that can greatly affects grain yield. Rice lodging is mainly caused by the changes in cell wall structure and cellular constituents. Cellulose content is the key factor affecting rice lodging and mechanical strength of stem.and choice In this study, overexpressing transgenic rice of a cellulose synthesis enzyme gene OsCesA4was usde to study the regulatory function of rice OsCesA4gene in cellulose synthesis and fiber characteristics. It provides theoretical basis for using the gene to improve germ plasm resources and molecular breeding of lodging resistance in rice. The main results were as the following:1. Positive transgenic rice lines were obtained by Agrobacterium-mediated transformation and validated in DNA and RNA transcription levels.2. Morphological observation showed that comparing to wildtype, the stem of the OsCesA4overexpressing transgenic rice plants is longer and thicker, the length and width of flag leaf, number of grains per panicle, height and length of grain of OsCesA4overexpressing transgenic rice increased. And this was further confirmed by statistical analysis of agronomic traits. The plant height, the length and width of flag leaf, spike length, stem length and width, number of grains per panicle and the seed setting rate of OsCesA4overexpressing transgenic rice all showed differences. Differences in grain number per panicle is perticularly remarkable. No obvious differences were found in number of tillers and thousand grain weight.3. Overexpressing of OsCesA4also decreased the brittleness of leaf, stem, leaf sheath and panicles in the overexpressing transgenic plant.4. Scanning electron microscope and paraffin section observation of OsCesA4overexpressing transgenic rice stem found that the cell wall thickness and the number of small vascular bundle of stem increased. And the sclerenchymatous cell of stem became denser and the cavity became smaller.5. Analysis of the chemical components of OsCesA4overexpressing transgenic rice stem found that the cellulose content was increased by9.5%, the lignin content was increased by2.6%, while the hemicellulose content was decreased about7%.6. Abiotic stress treatments of OsCesA4overexpressing transgenic rice showed that overexpressing of OsCesA4decreased tolerance to drought, high salt and high temperature in seedling. At booting stage, no obvious difference was found in morphological traits after high temperature stress. However, significant differences in fertile pollen rate and seed setting rate were observed between OsCesA4overexpressing transgenic rice and wildtype plants. After high temperature treatment, the fertile pollen rate in the wildtype plants was decreased to28.19%, while the fertile pollen rate in the OsCesA4overexpressing plants was still remained at53.78%. The seed setting rate of the wildtype plants was decreased by35.98%(from58.85%to22.87%) under high temperature treatment. While the seed setting rate of OsCesA4overexpressing transgenic rice was only decreased by21.66%(from62.88%to41.22%) under high temperature treatment., The seed setting rate of OsCesA4overexpressing transgenic rice was180%of that of the wildtype under high temperature treatment.