Petal development

MOEHS c p, TiAN L, OSTERYOUNG K w and DELLAPENNA D (2001) Analysis of carotenoid biosynthetic gene expression during marigold petal development , Plant J, 20, 401-12. 

Martin C, Gerats T. 1993. The control of pigment biosynthesis genes during petal development. Plant Cell 5 1253-1264. 

Kramer, E. M. and Irish, V. F. (1999). Evolution of genetic mechanisms controlling petal development. Nature, 399, 144-148. 

Petal development not delayed and corolla protecting the inner organs in bud (versus delayed in most Zygophyllaceae Ronse De Craene, pers. obs. in Fagonia, Zygophyllum and Tribulus - not delayed in Balanites this study)... 

Of all these, probably P-phenethyl alcohol (2) comes closest to the odor of fresh rose petals however, mixing all these components does not reproduce the total fine character of the natural oil. It has been determined that a number of trace constituents representing less than 1% of the volatiles are critical to the development of the complete rose fragrance (10). These include cis- and trans-i.ose oxide (1), nerol oxide (12), rose furan (13), /)i7n7-menth-l-en-9-al (14), P-ionone (15), P-damascone (16), and P-damascenone (3). 

When mitosis is blocked by colchicine, the treated cells may be left with an extra set of chromosomes. Plants with extra sets of chromosomes are typically larger and more vigorous than normal plants. Flowers developed in this way may grow with double the normal number of petals, and fruits may produce much larger amounts of sugar. 

Tea flowers are globular, about 3 to 5 cm in diameter, white, and delicately fragrant. They are borne in the axils of scale leaves (small leaves that do not develop further) and may occur singly or in small clusters. There are five to seven petals and an equal number of sepals. The flowers are mostly self-sterile and are produced in cycles corresponding to leaf growth, and require 9 to 12 months to form mature, round seed pods 1 to 1.5 cm in diameter. The tea plant is not generally allowed to flower during production cycles, with only a small number of the plants allowed to go to seed production to maintain seed stock. 

Simon It is just because in the species that I have discussed the carpels are the last organs to develop in the centre of the flower. There are a few exceptions in other plants where the carpels are not so central. We can introduce homeotic mutants that replace carpels with sepals or petals, and the same effects are seen. 

Miller CD, Buck WB, Hembrough LB, et al. 1982. Petal rat development as influenced by maternal lead exposure. Vet Hum Toxicol 24 163-166. 

Kondo, T. et al.. Structural basis of blue-color development in flower petals from Commelina communis. Nature, 358, 515, 1992. 

The cotton fibers used in textile commerce are the dried cell walls of formerly living cells. Botanically, cotton fibers are trichomes or seed coat hairs that differentiate from epidermal cells of the developing cottonseed. The cotton flower blooms only for one day and quickly becomes senescent thereafter. On the day of full bloom, or anthesis, the flower petals are pure white in most G. hirsutum varieties. By the day after anthesis, the petals turn bright pink in color and, usually by the second day after anthesis, the petals fall off the developing carpel (boll). The day of anthesis serves as a reference point for all subsequent events in the seed and fiber development. 

PRIMARY INFECTIONS. The mildew fungus overwinters as mycelium in the buds. If there is very severe frost in winter, some of the infected buds may die off, as the bud scales are not completely closed. In the closed buds the mycelium produces conidia, which infect the young leaves, blossoms and fruit when the buds open. Infection may occur at the greenbud or redbud stage if weather conditions are favourable. The first symptoms of primary infections can then be seen on the leaves and petals at flowering. Apart from the climatic conditions, for mildew infection to develop the tree must also have susceptible tissue (very young leaves) available. The leaves acquire age resistance to mildew at an even earlier stage than they do to scab. 

Fig.12 shows an example of development of single petalled flower with a pistil. 

Fig.12. Development of a single petalled chrysanthemum with pistil...

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