What are plant lectins? How are lectins plants\u2019 defense mechanism? How do the chemical defenses of plants affect the animals that eat plants?<\/p>\n\n\n\n
Plant lectins are the toxins produced by plants to keep predators from eating them. This chemical defense of plants can disorient or poison plant predators.<\/p>\n\n\n\n
Read more about plant lectins, the toxins that are plants\u2019 defense mechanism.<\/p>\n\n\n\n\n\n\n\n
Just as animals developed defenses against their predators (e.g. skunks spray their attackers and gazelles outrun many predators), plants developed their own methods of protecting their offspring\u2014their seeds\u2014to ensure their species carry on. <\/strong>One method is to produce toxins\u2014including plant lectins\u2014that poison, paralyze, or disorient predators or make the plant difficult to digest. Toxins are the plant’s defense mechanism.<\/p>\n\n\n\n Plants produce two types of seeds: Those that the plant wants predators to eat, and those it doesn\u2019t want predators to eat. <\/p>\n\n\n\n (Shortform note: When we talk about plants wanting<\/em> a certain result, we\u2019re not suggesting they have conscious thought, as people do. However, plants have evolved to encourage the survival and propagation of their species\u2014just like all living things\u2014and react to their environments, as we\u2019ll explore in a later section.)<\/p>\n\n\n\n Fruit trees want their seeds to be eaten, so the seeds have a hard shell or coating to keep them intact throughout the animal\u2019s digestion process; when the seed comes out in the animal\u2019s excrement\u2014essentially a nutrient-rich compost\u2014it\u2019s ready to grow. When predators eat these seeds (and later distribute <\/em>them) they\u2019re helping to spread them far and wide, which helps the plant\u2019s chance of survival<\/a>. If the fruit were to simply drop on the ground below the mother plant, those seeds would have to compete for sun, moisture, and nutrients. <\/p>\n\n\n\n However, plants don\u2019t want predators to eat these seeds until the seeds have fully developed the hard coating to survive digestion\u2014when the fruit is ripe. Consequently, unripe fruit is a different color (usually green) to indicate that it\u2019s not ready yet and contains toxins (including plant lectins) designed to make predators sick. Once the fruit is ripe, and the seeds are ready for their journey, the levels of lectins drop and the fruit develops its rightful color to alert animals that it\u2019s ready to eat. <\/p>\n\n\n\n At peak ripeness, fruit has high levels of sugar, and the type of sugar is designed to maximize the plant\u2019s chance of propagation: Instead of glucose, which raises insulin levels and lets your body know when you\u2019re full, fruits contain fructose, which doesn\u2019t send that message. As a result, predators keep eating more fruit\u2014and more seeds\u2014raising the plant\u2019s chance of spreading more seeds.\u00a0This is one of the chemicals defenses of plants. <\/p>\n\n\n\n Since fruits are naturally in season for only a portion of the year, this benefits animals by giving them a chance to stock up on calories during those windows of time. The same used to be true for people, but now that we have access to fruit year-round, we\u2019re eating more fruit and taking in more calories than we need.<\/strong> <\/p>\n\n\n\n When you buy out-of-season fruit, it\u2019s typically grown in another country, picked unripe, shipped, and then blasted with a gas that changes the fruit\u2019s color to make it look ripe. However, fruit that doesn\u2019t ripen naturally never gets the message from the mother plant to lower lectin levels. As a result, when you eat fruit out of season, you\u2019re ingesting large amounts of lectins.<\/strong> <\/p>\n\n\n\n In contrast to fruit, plants that grow in open fields don\u2019t <\/em>want their seeds to be eaten. These plants\u2014including grasses and vines\u2014don\u2019t benefit from their seeds being carried far and wide; instead, they want the seeds to drop and grow in place, so that when the mother plant dies during winter, the new plants will replace it in spring. <\/p>\n\n\n\n In order to deter predators from eating and spreading their seeds, these plants use toxins to weaken, paralyze, or sicken predators. In addition to plant lectins, which disrupt communication among cells<\/strong>, these toxins include:<\/p>\n\n\n\nPlants Evolved to Spread Their Seeds<\/strong><\/h3>\n\n\n\n
Seeds for Eating are Low in Plant Lectins<\/strong><\/h4>\n\n\n\n
Chemical Defenses<\/strong> of Plants for Naked Seeds<\/h4>\n\n\n\n