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They say an apple a day keeps the doctor away. That could certainly have some truth in it. Apples come in varieties: color, size, taste, whether seedless or with seeds. But have you ever wondered for a moment why some of the apples are seedless? Or do you just care about the crunchy feel-good taste you get from that first bite into your apple? Well, I am sure you’ll be excited to learn something new today on apples.
Why Are Some Apples Seedless?
Like most fruits, apples could be seedless from manipulation by breeders. Unlike oranges, however, seedless apples do not exist naturally. As such, seedless apples are not as common as the other seedless fruits that occur naturally.
It has taken several centuries’ worth of plant breeding to produce a small number of seedless apple varieties. Seedless apples have been recorded to yield small, poor-quality fruits.
However, it is not a pointless waste of time. For the farmer, seedless fruits offer many agronomic and economic benefits. Just as in the case of seedless fruits such as grapes, consumers are willing to pay more for the seedless apples.
Seedless varieties of apples crop without the need for pollinators. They are not dependent on the presence of specific insect species during the flowering stage. As such, their pollination is guaranteed dissimilar the crops dependent on insect pollination. Insects are affected by poor weather conditions and diseases and this significantly interferes with the success of pollination.
When seedless apples are hand-pollinated, they produce twice as much the normal number of seeds. But their flowers are so stunted. They fail to attract insect pollinators. It is this concept that forms the basis of breeding seedless apples.
A flower is made up of carpels, petals, anthers and styles. The four organs make up concentric circles with styles in the center and carpels on the outside. In a seedless apple plant, the positioning is achieved by creating an overlapping production of different members of a specific protein. The MADs-box protein family is what forms parts in the developing flower.
Pistillata is one of the proteins. It is manufactured in the second and third concentric circles of simple flowers. The protein converts the organs that would otherwise grow to become styles and carpels into petals and anthers respectively.
Genetic control of fruit production is still a subject of study. Nonetheless, the pistillata gene is associated with apples’ seedless varieties like in Granny Smith Apples. A length of extra DNA in the middle of the gene hinders the production of the pistillata protein in some seedless apple varieties. Such tendencies are common in the Wellington Bloomless and Spencer Seedless varieties.
The pistillata is involved in parthenocarpy, the production of fruits without fertilization. Apples are pome fruits. The seeds would otherwise be embedded in the fleshy tissue that derives from the anthers, petals and sepals.
Instead of petals and anthers, varieties such as Rae Ime blooms have extra sepals and styles. Such an arrangement is highly related with a classic flower mutation. The model plant Arabidopsis thaliana is a small plant that produces tiny seeds.
Producing seedless varieties of apples for commercial use is directly linked to the genetic modification of suppressing the MdPI cloned gene. The MdPI gene is a member of the MADs-box protein family. Gene suppression provides a shortcut to avoid the lengthy process of conventional plant breeding.
Growing seedless apples lessens another burden for the farmer. Seed development is associated with suppressing the following year’s flowers. It leads to biennial cropping, where a fruit tree carries a heavy crop one year and little or none the next. In growing seedless varieties, apple farmers avoid this problem altogether.
Seedless fruits are less vulnerable to the codling moth. The codling moth is a member of the Tortricidae family. These are major pests to agricultural fruits especially apples and pears. It, therefore, saves the farmer trouble from the major pest of conventional fruits.
What Varieties of Apples are Seedless?
1. Spencer Seedless Apples
The Spencer seedless apple started as a new discovery meant to do for the apple what ‘seedless’ has done for the orange citrus fruit. In this fruit, there is no core which makes a larger part of the fruit edible.
John F. Spencer from Colorado believed it would be possible to develop the occasional seedless apple into a stable variety. That is how it all began. After perseverance, he produced 5 trees which he used to bud and graft to stabilize the variety. It significantly improved the quality of the fruit which was initially not of commercial standard.
The efforts bore trees that bear seedless apples of good and fine quality. On the Spencer seedless apple tree, no blossom appears at any time on the trees. Only green buds appear but when they open they have no petals.
Spencer seedless apples grow as large as the common winter apple. They contain just as juice. The fact that the apples do not contain seeds or seed pockets comes in as a great convenience for commercial or home use.
2. Wellington Bloomless
The wellington bloomless is a distinctive old-fashion looking apple. Its rustic yellow color and a strongly inverted-conical shape, tapering from a wide top to a narrow bottom make it unique. This variety dispenses seedless apples.
These apples result from a strange mutation that occurs on apple trees: flowers without petals and fruits without seed. The flowering of the wellington bloomless apple trees is hardly noticeable.
The wellington bloomless tree blooms indistinctively without petals. The trees only appear to be green and have unopened buds on the branches. Fruits formed from such flowers are small with a shallow wide eye.
3. Granny Smith Apples
A crunchy flesh with a crisp, juicy and tart flavor, granny smiths are a common seedless apple variety. Ideally, they have a deep green color. You can get Granny Smith apples all year round but autumn is their season.
Granny smiths will be an excellent choice for your apple juice and apple pie. To make the best dessert, grab Granny Smiths from the later season. Their sugar levels are higher.