EAGER: Molecular Genetic Analysis of Early Endosperm Development by Microinjection of Maize Embryo Sacs

禾本科胚乳发育有几个不同的阶段：早期发育，包括双受精、合胞体形成和细胞化；分化，包括主要细胞类型（转移细胞、糊粉细胞、淀粉胚乳和胚胎周围细胞）的形成，有丝分裂和核内复制的时期，以及储存化合物的积累；成熟，包括程序性细胞死亡、休眠和干燥。突变体分析提供了关于影响胚乳发育分化和成熟阶段的基因的知识，但对早期发育及其后果知之甚少。对玉米和小麦的研究表明，发育早期细胞分裂的程度对粮食产量起着重要作用，但对其遗传基础知之甚少。虽然在大多数谷物中很难研究早期胚乳的发育，但对玉米来说比较容易，因为胚囊可以分离出来，胚乳可以在体外培养。本项目旨在开发一种新的方法，通过在授粉后2-3天（DAP）胚囊中微注射核酸来研究玉米胚乳的早期发育。这种方法在改造胚乳方面具有优势，因为它不需要与目前生产转基因玉米植物的方法相关的时间和劳动密集型程序。与这些实验相关的风险是存在的，但如果成功的话，对于确定调节早期胚乳发育的遗传机制可能是革命性的，并且可以在http://ag.arizona.edu/research/larkinslab/index.htm上访问的结果可能具有宝贵的实际应用价值。

Endosperm development in grasses has several distinct phases: early development, comprising double fertilization, syncytium formation, and cellularization; differentiation, which includes the formation of the main cell types (transfer cells, aleurone, starchy endosperm, and embryo-surrounding cells), the periods of mitosis and endoreduplication, and the accumulation of storage compounds; and maturation, which includes programmed cell death, dormancy, and desiccation. Mutant analysis has provided knowledge regarding genes that influence the differentiation and maturation phases of endosperm development, but much less is known about early development and its consequences. Studies in maize and wheat suggest the extent of cell division during early development plays an important role in grain yield, but little is known about its genetic basis. While it is difficult to study early endosperm development in most cereals, this is easier with maize, because the embryo sac can be isolated and the endosperm cultured in vitro. This project seeks to develop a novel method to investigate early development in maize endosperm by microinjecting nucleic acids into 2-3 days after pollination (DAP) embryo sacs. This approach has advantages for transforming endosperm because it does not require the time and labor-intensive procedures associated with current methods of producing transgenic maize plants. There are risks associated with these experiments, but if successful could be transformative for identifying the genetic mechanisms that regulate early endosperm development and the results, which can be accessed at http://ag.arizona.edu/research/larkinslab/index.htm, could have valuable practical applications.