Rapid in-vitro plant regeneration of cotton (Gossypium hirsutum L.).

A rapid, clonal propagation procedure has been developed to regenerate mature cotton (Gossypium hirsutum L.) plants from pre-existing meristems that were excised from in-vitro-grown tissues. This plant regeneration procedure was applicable to diverse cotton germplasms and required specific concentrations of 6-benzylaminopurine (BA) depending on the origin of the meristems. All shoots regenerated directly without a callus phase. Screening BA concentrations (0.0-10.0 µM) demonstrated that shoot meristems (apices), secondary leaf nodes, primary leaf nodes, and cotyledonary nodes derived from in-vitro-grown 28-day-old seedlings (Paymaster HS26) varied in their ability to form elongated shoots depending on the level of BA. Indicative of a germplasm-independent procedure, a BA concentration screen (0.0, 0.3, 1.0 µM) demonstrated that explants with pre-existing meristems, excised from diverse germlines, were also able to form elongated shoots at 0.3 µM BA. In most cases, elongated shoots derived from this procedure were rooted by a two-step process: an in-vitro maturation step (Murashige and Skoog medium-activated charcoal) followed by planting into soil after basal application of Rootone. This BA plant regeneration procedure was rapid, reproducible, and highly efficient for Stoneville 7A, Paymaster HS26, and other high-fiber-yielding germlines. Regenerated plants were phenotypically normal and all of the mature plants regenerated to date have initiated flowers and set viable R1 seeds.

Interrelationships of glandular trichomes and cannabinoid content. II. Developing vegetative leaves of Cannabis sativa L. (Cannabaceae).

Gland number and cannabinoid content were quantified during ontogeny of vegetative leaves from three clones of Cannabis. Initiation of capitatesessile and bulbous glands was found to occur uniformly during leaf development. Cannabinoids were synthesized throughout leaf development as well, but at a decreasing rate. A positive correlation was found for total capitate-sessile glands per leaf as compared with total cannabinoid content of the leaf. The data also indicated that other leaf tissues in addition to the glands may contain cannabinoids.

Interrelationships of glandular trichomes and cannabinoid content. I: Developing pistillate bracts of Cannabis sativa L. (Cannabaceae).

Gland number and cannabinoid content for three clones of Cannabis were compared. Cannabinoid levels and mature glands were quantified throughout progressive stages of pistillate bract development in order to define possible interrelationships between glands and cannabinoids. Similar trends occurred among the clones for each gland type while individual cannabinoids displayed a different pattern in each clone. Gland initiation and development as well as cannabinoid synthesis were found to occur during bract ontogeny for all three clones. A positive correlation existed for the total number of capitate glands per bract compared to the total cannabinoid content of the bract. The study also suggested that the glands may contain the majority of the cannabinoids present in the bract.