Genetic and Environmental Factors that Influence Microgametophytic Variation

在花粉发育、花粉萌发和花粉管生长期间，花粉(微配子体)中的很大一部分遗传物质被读出。因此，花粉的性能(萌发速度、花粉管生长速度和受精能力)可能会受到其遗传构成、与其生长所通过的花的物质部分的相互作用、温度等环境条件的影响，以及产生花粉的亲本提供给花粉粒的资源(如氮和磷)。斯蒂芬森博士和温莎博士将继续对影响花粉性能的因素进行详细研究。他们将确定这些因素是否会导致非随机受精，以及非随机受精是否会影响后代的表现。具体地说，他们将使用德克萨斯南瓜来检查通过只允许生长最快的花粉管实现受精来选择花粉管生长的程度。接下来，他们将研究土壤磷含量的变化对花粉产生、花粉粒大小、花粉中储存的磷的数量以及花粉表现(混合授粉的能力)的影响。最后，他们将把花粉产生期间的温度影响与花粉萌发期间的温度对花粉表现的影响分开。这些实验与之前和正在进行的研究相结合，将得出影响花粉性能的遗传和环境因素的完整图景，基因从一代到下一代的非随机传递，以及它们对由此产生的后代的影响。这些研究的结果将解决和澄清植物种群生物学中一些最活跃的辩论问题。此外，这项研究还将对应用科学产生深远的影响。与传统的育种计划和较新的生物技术计划相比，利用花粉来选择在农业上令人满意的特征的可能性代表着相当大的时间、金钱和空间的节省。最后，有可能利用花粉监测环境退化，确定哪些物种对特定形式的污染敏感，并培育出更具抗性的植物品系。

A large portion of the genetic material in pollen (microgametophytes) is read off during pollen development, pollen germination and pollen tube growth. Consequently, the performance of pollen (speed of germination, pollen tube growth rate and ability to achieve fertilization) can potentially be affected by its genetic makeup, by its interactions with the material portion of the flower through which it grows, by environmental conditions such as temperature, and by the resources (e.g. nitrogen and phosphorus) provided to pollen grains by the pollen-producing parent. Drs. Stephenson and Winsor will continue their detailed investigations of the factors that affect pollen performance. They will determine if these factors result in non-random fertilization, and if non-random fertilization affects the performance of the progeny. Specifically, they will use Cucurbita texana to examine the extent to which pollen tube growth can be selected for by allowing only the fastest growing tubes to achieve fertilization. Next, they will examine the effects of variation in the amount of soil phosphorus on pollen production, pollen grain size, the quantity of stored phosphorus in pollen, and the performance of pollen (ability to sire seeds in mixtures). Finally, they will separate the effects of temperature during pollen production from the effects of temperature during pollen germination on pollen performance. These experiments, when combined with prior and ongoing studies, will result in a complete picture of the genetic and environmental factors that influence pollen performance, the non-random transmission of genes from one generation to the next, and their effects on the resulting progeny. The results of these studies will address and clarify some of the most actively debated issues in plant population biology. In addition, this research will have far-reaching implications for the applied sciences. The possibility of using pollen to select for agriculturally desirable traits in the pollen represents a considerable savings of time, money and space over both traditional breeding programs and the newer biotechnology programs. Finally, it may be possible to use pollen to monitor environmental degradation, to determine which species are susceptible to particular forms of pollution, and to develop lines of plants that are more resistant.