Another moral issue is that, if we have the power to increase a plant's resistance to disease, for example in such a way that more food is produced and hunger is alleviated, isn't there a moral imperative to do so? To use whatever technology is available to reduce human suffering?
Ethically, you can take the controversy surrounding Monsanto, a firm that genetically engineered corn seeds so that they would not reproduce seeds at the end of the life cycle of the plant, thus making small farmers, particularly in Latin America, dependent on buying the company's seeds year after year. This is an example of genetically engineering plants for profit.
Scientifically in terms of ethics, messing with the natural makeup of plants and introducing essentially artificial or man made ones alters the balance of natural evolution. It interferes with food chains and habitats in ways we do not understand, so if we cannot predict all the negative results of a crop modification, ethically, should we do it?
The main moral and ethical issue raised by opponents of genetically modified plants and animals is that these organisms might prove to be unhealthy. They think that they might somehow hurt people who consume them. Alternately, they think that plants might end up cross breeding with other plants in ways that will be harmful.
The issue here is whether to take something that will help a lot of people and ban it because it might have harmful effects that are not now known. This is a perennial question in science -- do we move quickly and help people now or move carefully so we do not inadvertantly harm them while trying to help?
Moral and ethical issues generally involved with the development of science are the possibility of use of the science and technology for the wrong purposes and the methods used for achieving the scientific and technological progress. For example, the technology has been used in the past to develop means of improving the condition of people as well as for constructing means of mass destruction. An example if issue of ethics and morals in methods of development of science is the use of animal testing in medical and biological research.
A third very important issue linked with science and technology development is unintended and at times unforeseen negative impact of application of science and technology. A major area of this negative side effect is the environmental pollution. But then there can be many more different types of undesirable fall outs of technology and development.
The moral and ethical issues related to genetically modified (GM) crops, fall mainly in this third category. The GM crops are developed to offer specific advantages like higher yields of crops at reduced cost and compressed time cycle, and greater resistance of crops to damage by diseases and other environmental factors. These features of GM crops are clearly in the interest of humanity, and there ire no apparent of moral or other reasons to oppose crops like these. But then there are hidden costs and problems associated with use of GM crops. To begin with, the quality of the GM products may harm the people. For example the GM crops may give higher yield of food product, but the food may be inferior in terms of lacking many essential nutrients. Much worse the product may contain some harmful ingredients in more than sage quantities. People may start using such products because these are cheaper to produce, but in the long term they may suffer from many health problems because of this. The GM crops may also hurt the environment. The crops may be resistant to certain diseases themselves, but may cause such diseases to spread to other type of crops. Also the GM crops may deplete some essential nutrients from the soil very fast affecting the suitability of soil for farming in the long run.
These problems associated with GM crops may be unexpected or unknown to some extent, but at times it also happens that for earning profits the business firms dealing in seeds and technology of GM crops do not completely disclose the negative aspects of their products. Also at times the products are brought into market without enough study on their possible harmful effects. Of course, the ethical and moral issues of this type are perhaps more in the domain of business practices rather than science and technology.
Another business practices associated with GM crops which is suspect on the moral and ethical grounds is the practice of selling seeds for GM crops that produce crops that cannot produce fresh seeds. This is clearly designed to keep the farmer dependent on monopoly of seed supplier. This practice is an attempt to perpetuate monopolistic behaviour which is considered illegal in most of the progressive countries of the world including USA and India.