Growth of the gynophore of the peanut Arachis hypogaea. 1. Intact and decapitated gynophores

Abstract

The origin and development of gynophores were studied in a two-seeded, bunch-type peanut ciltivar, Bukene No. 2. Plants were grown and experiments carried out in a greenhouse. An intercalary meristem is formed at the base of the fertilized ovary. When the gynophore is about 6 mm long, it responds positively to gravity, showing sigmoid growth. Marking experiments showed that the meristem extended to 6 mm proximal to the tip of the gynophore, the greatest growth occurring between 2 and 3 mm from the tip. Histoautoradiography showed that the greatest number of labelled nuclei occurred in segment 2; however, because of differences in cell length, the highest proportion of labelled to unlabelled nuclei occurred in segment 3, the region where the greatest overall extension occurred. Both cell division and cell elongation are involved in extension growth. Excision of the ovary resulted in cessation of elongation growth after 4 days or less, together with loss of meristematic features. Removal of the distal half of the ovary was less effective. It is postulated that the developing ovary provides growth factors necessary for maintenance of growth in the intercalary meristem of the gynophore.

Comparative transcriptome analysis of basal and zygote-located tip regions of peanut ovaries provides insight into the mechanism of light regulation in peanut embryo and pod development

“…Two ovules are located 2–3 mm from the tip region of the pegs. Peg elongation is caused by the intercalary meristem, which is just behind the ovary [ 1 ]. If pegs are artificially hindered from soil penetration, the embryos in these pegs are eventually aborted [ 22 ].…”

“…Further embryonic development is inhibited under light or normal day/night conditions. However, ovary elongation continues due to the activity of an intercalary meristem just behind the pre-embryo [ 1 ]. This elongated ovary containing the embryo is usually referred to as the “peg” [ 2 , 3 ] by peanut growers and researchers, while the term gynophore is primarily used in the literature.…”

Influence of Prohexadione Calcium on Pod Yield and Pod Loss of Peanut

“…Delaying digging at Lewiston in 1999 and 2000 and at Rocky Mount in 2000 increased percent pod loss. Increased percent pod loss would be expected when digging is delayed because the gynophore begins to senesce when the fruit reaches physiological maturity (Shushu and Cutter, 1990). This would mean a decrease in the strength of the gynophore at a later digging date.…”

Comparative Proteomics of Peanut Gynophore Development under Dark and Mechanical Stimulation

“…Previous research indicated that gynophore elongation and embryo development are controlled by growth regulators, such as light, touch, gravity, and phytohormones. , In addition, the physiological changes that occur during gynophore development have decisive effects. − Studies have shown that dark, mechanical stimulation and gravitation were necessary for peanut development . Light stimulates gynophore elongation and inhibits embryo and pod growth, while dark arrests gynophore elongation and promotes the development of ovary into a pod. ,, Meanwhile, the tip of the gynophore is highly sensitive and responsive to mechanical stimulation. , After gynophore penetrated into the soil, normal mechanical stimulation occurred and subsequently lead to the arrest of gynophore elongation, while it promoted the development of pod underground . If the elongating peanut gynophore hung in the air and did not penetrate into the soil, the ovary would not grow and the tip of the gynophore would not swell, even if the growing gynophore was in the dark without mechanical stimulation.…”

“…Thus, mechanical stimulus is supposed to be necessary for pod development, and the penetration into the soil of the gynophore is prerequisite for the fructification of the peanut. , Moreover, a combination of IAA and gibberellin was reported to be responsible for normal gynophore elongation, and cytokinin was involved in the early stage of cell division. IAA is a key regulator and may play the most important role throughout the whole process of gynophore development. − However, the mechanisms of molecular changes and key regulators involved in special physiological processes during the peanut gynophore formation and development have not been studied in detail.…”