Here are some important or interesting points in which you may have interest:

Why were tomatoes seen as poisonous for so long (at least two centuries) ? 

• There is actually no clear and scientific conclusion. One hypothesis is that the tomato is similar in shape to a local poisonous lycophyte (a generic term for plants such as eggplant and tomato). This hypothesis is reasonable, since most non-artificially cultivated lycopersicon plants are in fact poisonous, and only a few species are available for human consumption. Another assumption is that a chemical reaction between the acid in the tomato and the tin-alloy cutlery that was more commonly used five hundred years ago produced a toxic substance that could be fatal. In history, more than one death was recorded from tomato consumption, but we have no way of confirming their truthfulness. 
• It took the Spanish almost one hundred years to accept the tomato, followed by the Italians. As for the rest of Europe, tomatoes were consumed one to two centuries later. The earlier adoption of the tomato by Italians was due to the fact that parts of southern Italy were occupied by Spain at the time, which indirectly contributed to the spread of the tomato.

• The earliest ketchup originated in Southeast Asia as a savory seasoning made from seafood. The sweetketchup we’re familiar with didn’t appear until around 1850. Long ago, however, Italy had numerous types of tomato sauces. Italy is known for its rich culinary traditions and diverse regional specialties, and each tomato sauce has its own unique flavor and purpose, like Marinara, Napoletana, Bolognese, Puttanesca, Arrabbiata, etc. These are just a few of the many tomato sauces available in Italy. In fact, each region and even each family may have its own unique tomato sauce recipe, adapted to individual tastes and traditions.
• Please do not use the word “ketchup” to describe the tomato sauces when talking to the Italian people, or they may feel it is kind of an insult. For them, the ketchup is just something for fries or as a side for some dishes.

• In my opinion, the answer would be that without tomatoes, food waste may increase. Tomato is a widely used ingredient that plays an important role in many dishes. Without tomatoes, people may substitute other ingredients, which may lead to more food waste.
• In addition, tomatoes are also used in the preparation of a variety of processed foods, such as ketchup, which have a longer shelf life and reduce food waste. Therefore, the absence of tomatoes may complicate food preservation and substitution options, which may increase food waste.
• Not only food waste, the absence of tomatoes may also generate more transportation costs and waste; remember, tomatoes can be planted almost everywhere in the world, even in high-latitude regions like Sweden. We may have to spend a lot more if people’s requirements cannot be realized locally. 
• Last but not least, among many countries and nations, tomatoes are one of the most important food resources that everyone can afford, and it is difficult to find any substitute. Not only tomatoes, the loss of such basic food resources may lead to severe social inequality. In Chapter 3 of the fiction, I am trying to discourse such potential possibilities with a tune of black humor.