A method is disclosed to achieve genetic transformation of cotton plants and lines. Immature cotton tissues are genetically transformed in vitro, by Agrobacterium-mediated genetic transformation. The resultant cotton tissues are subjected to a selection agent or agents to screen for transformants. The transformed cultures are then induced to commence somatic embryogenesis. One possible regime for regenerating such somatic embryos into whole cotton plants is disclosed.

Genetic engineering of cotton plants and lines

(1990). Regulatory mechanisms involved in the transition from seed development to germination. Critical Reviews in Plant Sciences: Vol. 9, No. 2, pp. 155-195.

Regulatory mechanisms involved in the transition from seed development to germination.

A method of genetically engineering a fiber-producing plant is disclosed. This method first comprises the step of constructing a plant expression vector that comprises a protein coding sequence and a DNA sequence capable of promoting gene expression in fiber cells, wherein the DNA sequence is homologous to a sequence selected from the group consisting of 12 different genomic sequences. The method next involves introducing the expression vector into a fiber-producing plant wherein the protein coding sequence is expressed in the fiber cells of the fiber producing plant. A method of obtaining a DNA sequence capable of promoting gene expression in fiber cells is also disclosed.

Genetically engineering cotton plants for altered fiber

Somatic embryogenesis is the formation of an embryo from a cell other than a gamete or the product of gametic fusion This is not an artificial phenomenon, and is known in nature as a form of apomixis called adventitious embryony, first described by Strasburger in 1878 [1] (see Sharma and Thorpe, this volume) Although Steward [2] and Reinert [3] are generally given credit for the first descriptions of somatic embryogenesis in 1958, such credit might more properly belong to Levine [4], who in 1947 reported the recovery of carrot “seedlings” from tissues exposed to low levels of α-naphthaleneacetic acid, via a process whose description sounds very much like somatic embryogenesis

Morphogenic Aspects of Somatic Embryogenesis

This review will summarize molecular and genetic analyses aimed at identifying the mechanisms underlying the sequence of events during plant zygotic embryogenesis. These events are being studied in parallel with the histological and morphological analyses of somatic embryogenesis. The strength and limitations of somatic embryogenesis as a model system will be discussed briefly. The formation of the zygotic embryo has been described in some detail, but the molecular mechanisms controlling the differentiation of the various cell types are not understood. In recent years plant molecular and genetic studies have led to the identification and characterization of genes controlling the establishment of polarity, tissue differentiation and elaboration of patterns during embryo development. An investigation of the developmental basis of a number of mutant phenotypes has enabled the identification of gene activities promoting (1) asymmetric cell division and polarization leading to heterogeneous partitioning of the cytoplasmic determinants necessary for the initiation of embryogenesis (e.g. GNOM), (2) the determination of the apical-basal organization which is established independently of the differentiation of the tissues of the radial pattern elements (e.g. KNOLLE, FACKEL, ZWILLE), (3) the differentiation of meristems (e.g. SHOOT-MERISTEMLESS), and (4) the formation of a mature embryo characterized by the accumulation of LEA and storage proteins. The accumulation of these two types of proteins is controlled by ABA-dependent regulatory mechanisms as shown using both ABA-deficient and ABA-insensitive mutants (e.g. ABA, ABI3). Both types of embryogenesis have been studied by different techniques and common features have been identified between them. In spite of the relative difficulty of identifying the original cells involved in the developmental processes of somatic embryogenesis, common regulatory mechanisms are probably involved in the first stages up to the globular form. Signal molecules, such as growth regulators, have been shown to play a role during development of both types of embryos. The most promising method for identifying regulatory mechanisms responsible for the key events of embryogenesis will come from molecular and genetic analyses. The mutations already identified will shed light on the nature of the genes that affect developmental processes as well as elucidating the role of the various regulatory genes that control plant embryogenesis.

/pdf/zygotic-embryogenesis-versus-somatic-embryogenesis-2iavmg4wwu.pdf

Zygotic embryogenesis versus somatic embryogenesis

Seventeen cultivars of cotton (Gossypium hirsutum L.) were evaluated for callus initiation and maintenance using 3 initiation media and 3 maintenance media. After a series of transfers of a 3% glucose media, calli were placed on a 3% sucrose medium. After several weeks calli were observed for the presence of embryo-like structures. Cultivars Coker 201 and Coker 315 were identified as embryogenic. Embryogenic callus has since been routinely obtained within 6 weeks by initiating callus on glucose media for 3-4 weeks followed by transfer to sucrose media. Histological examination has shown that embryos are derived from isodiametric, densely cytoplasmic cells and follow predictable patterns of development. Upon maturity, transfer to auxin-free media with reduced sucrose levels results in embryo germination. Regenerated plants can be transferred to greenhouse within 90 days of callus initiation.

https://link.springer.com/content/pdf/10.1007/BF00269112.pdf

Characterization of somatic embryogenesis and plant regeneration in cotton (Gossypium hirsutum L.).

The storage protein content of somatic embryos of Gossypium hirsutum L. cv. Coker 201 was determined using extinction level, antigen/antibody association detection methods. Mature storage protein was first detected in early globular-stage somatic embryos at a total concentration of 0.36% of the embryo protein mass. Tulip-stage and mature somatic embryos were comprised of 3.0% and 1.3% mature storage protein, respectively. Maximum storage protein synthesis was found to occur during early globular- and early heart-stages. During this period of development, significant levels of protein precursors were found also to accumulate. The pattern of storage protein synthesis, processing and accumulation paralleled the pattern that has been reported for the zygotic system, although somatic embryos accumulate storage protein at much earlier stages and to a lesser degree. The possibility of using complex biochemical pathways to monitor embryogenic systems in vitro is discussed.

R. C. Shoemaker

Papers

Characterization of somatic embryogenesis and plant regeneration in cotton (Gossypium hirsutum L.).

Storage protein accumulation patterns in somatic embryos of cotton (Gossypium hirsutum L.)