When talking about seed, you might think of an undeveloped plant embryo. However, that is not the only thing a seed is. Generally, it is a food reserve enclosed in a protective outer covering. It can also refer to a tuber or a husk.
Endosperm
The endosperm of a seed is the storage tissue that contains food, which is needed to support a developing embryo. It is a tough outer layer that protects the embryo. When a seed sprouts, it lives off the stored food.
During germination, endosperm weakening enzymes are involved in the process of limiting the embryo’s growth potential. Several studies have investigated the role of these enzymes in the degradation of endosperm cell walls. Some of these studies have shown that the activity of endo-b-mannanase is associated with the emergence of a radicle.
Endo-b-mannanase activity is induced during priming in the micropylar endosperm tip of tomato seeds. ABA has been found to inhibit this enzyme, and it is also implicated in endosperm cap weakening.
In an attempt to understand the mechanisms underlying the effect of ABA on the endosperm, Nonogaki et al. studied the effect of ABA on endosperm cap cell wall structure using TEM. They found that the outermost cell wall bordering the testa was thicker than the other cell walls.
Seed coat
The seed coat is a protective covering that surrounds the embryo of a seed. It also serves as a channel to transmit information to the internal parts of the seed.
Angiosperm seeds are composed of an embryo and endosperm. Endosperm is nourished by the growing embryo. In angiosperm plants, fertilization occurs by double fertilization. Sperm cells from pollen fuses with female gametes inside the flower. Once the zygote forms, the embryo is ready to germinate.
Seed coats are multilayered structures that provide protection for the embryo and endosperm. They protect the seed from environmental stresses such as water and temperature fluctuations.
The inner layer of the seed coat is called the tegmen. This layer contains parenchyma and macro- and osteosclerids. These tissues undergo specific differentiation to serve a variety of functions.
Seedling conditions
Seedlings are a critical stage of crop life cycles and are vulnerable to different abiotic stresses. Plants respond dynamically to stresses, which require mathematical modeling. For example, chlorosis under salinity is a well-studied abiotic stress. However, the occurrence of salt-induced chlorosis under drought conditions is less well understood. This study examined the response of European winter barley cultivars to osmotic stress.
To identify potential genes involved in osmotic stress, 4885 gene-based SNP markers were mapped. Twenty-eight significant loci were identified. Several pathways were responsive, including a cascade dependent on Ca2+ signaling. ABA signaling was also proposed as a candidate for some osmotic-related QTL.
The response to osmotic stress was evaluated in parallel with non-stress conditions. Overall, the response curves showed a gradual reduction of variability. Two QTL were common among seedling growth under osmotic and non-stress conditions.
Dormancy
Seed dormancy is an adaptive trait of higher plants. It allows the embryos to survive in unfavorable ecological conditions. Moreover, it helps in the natural distribution process.
Different dormancy forms have evolved in response to climate. These dormancy forms are morphological, physiological and combined dormancy. There are several reasons behind dormancy, but the main cause is poor development of the embryos.
Several species of seeds exit from dormancy only after exposure to fluctuating temperatures. Similarly, gaseous environment is also known to affect germination rates. As a result, seed dormancy is a critical factor for the survival of plants.
Seeds are classified into three categories based on the nature of their dormancy. This is determined by genetics. The genes responsible for dormancy are found within the seed.
Plants that produce seeds
Plants that produce seeds have special structures that make it possible for them to reproduce. They represent a different solution to problems such as harsh environments and the dispersal of offspring. Flowering plants, for example, evolved from seed plants.
In flowering plants, a plant that produces a fruit encloses its seeds within the fruit. A seed is a pod that contains an embryo, which has already begun to develop. The embryo is nourished by food in the seed.
There are many different types of plants that produce seeds. These include gymnosperms, angiosperms, and ferns. Most flowering plants are grouped into two groups: Angiosperms and Gymnosperms.
Gymnosperms are the first seed plants. Gymnosperms are characterized by their lack of true flowers. This makes them less likely to be eaten and therefore they are important in ecosystems. Today, there are about a thousand species of gymnosperms.
