Phenotype Descriptions by Category

Plant Form
Dwarf, Petite


Petite plants are shorter than Standard rapid-cycling Brassica rapa and all parts of the plants are reduced in size, proportional to their height. Petite plants are a more intense, green color than Standard.The Petite stock originated from a naturally occurring mutation, discovered early in the history of rapid-cycling Brassica rapa.The Petite stock has been used as the basis for developing other stocks, including AstroPlants, a stock used by NASA Space Shuttle experiments. AstroPlants were selected to meet NASA’s “5-10-15” specifications: plants that produced 5 seed pods, grew no taller than 10 cm, and flowered in 15 days.
Dwarf, Intermediate Dwf2 Plant height significantly reduced from standard. Leaves and flowers are similar in size to standard.
Elongated Internode


Elongated internode plants produce more gibberellic acid (GA), a plant growth hormone, than Standard rapid-cycling Brassica rapa. The excess GA yields elongated hypocotyls and stem internodes, so the plants are tall and spindly.
The elongated internode (also known as tall) phenotype is first apparent 2-3 days after germination, when the seedling hypocotyl continues to extend beyond the height of the Standard hypocotyl. The exaggerated elongation continues throughout the plant’s development, yielding tall adults. Plants of this stock tend to be a lighter green than Standard plants.
The height of elongated internode varies considerably; the shortest plants are similar in height to the tallest Standard plants.
Elongated internode originated from a naturally occurring mutation, discovered early in the history of rapid-cycling Brassica rapa.
Cultivar is reported to be a Phytochrome B mutant.


Rosette plants produces less gibberellic acid (GA, a plant hormone) than Standard rapid-cycling Brassica rapa. The GA deficiency prevents the stems from elongating (extreme shortening of internodes), so the leaves remain near soil level and the plants appear dwarfed. The leaves are a deep, green color.
Rather than the hypocotyl lifting the cotyledons above the soil 1-2 days after the seeds are sown, the cotyledons push their way out, emerging up to 4 days after planting.
Leaf development and flowering are delayed by a few days. Flowers are densely clustered on the short stems. With care, they can be pollinated. The resulting seed pods are short and stubby because the carpels do not elongate normally.
The Rosette stock originated from a naturally occurring mutation, discovered early in the history of rapid-cycling Brassica rapa.
Fused Cotyledons and Calyx Fca   Margins of cotyledons and petioles are more or less fused to form cone-shaped structures. Fused cotyledons are commonly associated with the fusion of sepal margins creating a tubular calyx that restricts petal and anther emergence.
Hairy Hir(1-9) Hairs, a type of trichomes, are found in varying numbers, mostly on the stems and leaves. Number of hairs on leaves and stems is intermediate and variable.
Hairless Hir(0) None or very few hairs on any plant part. Hairless phenotype may be conditioned by one or a few genes.


Stem and Leaf Pigments
Anthocyanin Expression



Plants produce a purple pigment (anthocyanin) that is visible on the stems and hypocotyls, under cotyledons, and at the leaf tips and hydathodes. The purple color is caused by the presence of anthocyanin, a pigment found in many plants. The intensity of the purple color is affected by the environment. Higher light intensity and/or less fertilizer yields a deeper purple color. 



Plants of this stock appear a brilliant green, with no purple pigment (anthocyanin) on the stems, leaves, or other plant parts.
Anthocyaninless plants do not produce anthocyanin; however, many stocks expressing the anthocyaninless trait also have a genetic background for high expression of purple anthocyanin when in the heterozygous condition.
Yellow Green




In the yellow green phenotype, the cotyledons, leaves, stems, and developing seed pods are a pale yellow green color; this contrasts the darker, more intense green of Standard rapid cycling Brassica rapa.
This yellow green trait was first detected as a single, pale-yellow seedling in a population of otherwise green seedlings. Several discrete yellow green traits have been identified, with variation in expression of yellow green color on different plant parts.
Cytoplasmic Variegated (Var) Variegated plants are characterized by distinctive patterns of green and white on any plant parts that contain chlorophyll. The variegation can range from large patches of white to fine, white mottling amid mostly green.
Inheritance of the variegated trait is cytoplasmic, which means that the genetic information is not part of the DNA in the cell nucleus. Variegation is inherited uniparentally through the egg, not the pollen. Expression appears to result from variation in number of normal and abnormal chloroplasts that segregate somatically at time of cell division. Large white sectors originate from cell lineages having high proportions of abnormal plastids early in tissue development.
After fertilization, the zygote contains a mixture of normal (green) and mutant (white) chloroplasts.
Glossy Glo Stems and pods lack dull waxy bloom, appearing shiny or glossy green, less prominent on the leaves.


Atrazine Resistance
Atrazine Resistant (Tzr) Plants with Atrazine resistance grow normally under exposure of leaves or roots to concentrations of Atrazine herbidice that rapidly kills Standard rapid cycling Brassica rapa lacking the (tzr) gene. Resistance is conferred through a mutation in the chloroplastic genome and is transmitted uniparentally through the cytoplasm of the egg.


Floral and Reproductive
Apetalous Apt Flowers are largely without petals. On some plants, some flowers have one or more petals. Expression of petal number is variable.
Cytoplasmic Male Sterile (Mst) Flowers lack anthers. Stamens are filamentous or petaloid. Plants are functionally female.
Male Sterile Mst2 Approximately half of plants in the population are male sterile, having vestigial anthers lacking pollen; the other half are male fertile with normal anther development and pollen production.
Orange Yellow Petal Oyp Petals appear orange-yellow, particularly when viewed in natural light. Also sometimes referred to as pale orange petal (Pop).
Revolute Petal Rvp Petals strongly folded back on themselves, revolute, in buds and open flowers.