Fruit-induced &amp; apical senescence in <i>Pisum sativum</i> L.

Lockhart, James A.; Gottschall, Virginia

doi:10.1104/pp.36.4.389

Cited by 73 publications

(36 citation statements)

References 8 publications

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“…Inasmuch as the deseeded plants showed no senescence, while the shams senesced normally (with only a slight lag due to a small delay in fruit maturation), it can be inferred that the failure to senesce is due to seed removal. These experiments have also been performed on other monocarpic plants; deseeding has delayed senescence in peas (6) and red kidney beans (13).…”

Section: Discussionmentioning

confidence: 99%

Studies on the Behavior of the Senescence Signal in Anoka Soybeans

Lindoo¹,

Noodén²

1977

Plant Physiol.

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Soybean, a monocarpic plant, has been found to undergo rapid senescence as its fruits mature. In soybeans (Glycine max[L.J Merrill) cv. Anoka, foliar senescence begins during the period of most rapid pod-fill (seed growth), and it can be eliminated by surgical removal of the seeds at an early stage of their growth. Experiments in which fruits are removed from some regions of the plant but aBowed to remain on other regions have established that the transmission of the senescence signal is limited; it affects mainly those leaves nearest to the nodes bearing the fruits. The implications of this localized signal movement are discussed.The phenomenon of monocarpy (a single fruiting phase followed by death) has been recognized for some time, and various theories have been offered to explain the mechanism by which flowering/fruiting induces the death of the entire plant (8, 9). In Anoka soybeans, senescence begins when most of the fruits on the plant are undergoing rapid pod-fill (5), and we and others (4) have found that the fruits cause the rest of the soybean plant to begin senescence which leads to death. In this paper, we will use the term "senescence signal" to refer to this, as yet, uncharacterized correlative influence of the fruits on foliar senescence without attempting to limit the notion of a signal to any one of the possible mechanisms for monocarpic senescence. Information on the behavior of this killing signal, such as degree of movement within the plant, will be important in analyzing the mechanism by which the fruits induce death. The results discussed here have been presented at meetings (10, 11 In other surgical experiments, the seeds were excised by slitting the fruit pods with a razor blade next to each seed and parallel to the main longitudinal vein of the pod but without touching the seed (see Fig. 1). The seeds were then forced out through the slits and lanolin was applied to the cuts. In shamoperated plants, the pods were treated in the same way except the seeds were not forced out.Measurement of Senescence and Fruit Development. Generally, each treatment group consisted of five plants (an average value was used in the figs.), and each experiment was repeated at least once.Senescence was measured as the percentage of total leaves on the plant greater than '/2 yellow (scored visually). This visual method of scoring leaf chlorosis has been described in detail and has been correlated with methods which use leaf absorbance of light at 660 nm or which measure amounts of extractable Chl (5).In order to describe fruit maturation quantitatively, we developed a measure of the average fruit maturity based on the proportion of total fruits in each of five fruit development stages given below.Stage 1: pod length greater than 1 cm but pod not full width and the characteristic bulges of the seed cavity not yet developed.Stage 2: pod full width but the largest seed less than 1 cm long (can be estimated by examining the fruit in front of a bright light).Stage 3: seed length greater than or equal to 1 c...

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Section: Discussionmentioning

confidence: 99%

Studies on the Behavior of the Senescence Signal in Anoka Soybeans

Lindoo¹,

Noodén²

1977

Plant Physiol.

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“…Since this GA, co-chromatographed with authentic [,H]GA, and was biologically active, they suggested that GA, might be GA, and that the presence of an increased amount of this GA was responsible for the extended growth potential of SD-grown G2 pea. Lockhart and Gottschall (1961) also noted the fact that GA, delayed apical senescence in Alaska peas, but they concluded that the effect was indirect. Ecklund and Moore (1968) confirmed the senescence-delaying effect of GA, on the apical bud of pea plants and were able to show that AMO-1618, an inhibitor of GA biosynthesis, accelerated senescence in Alaska peas.…”

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The Control of Apical Bud Growth and Senescence by Auxin and Gibberellin in Genetic Lines of Peas

Zhu

Davies

1997

Plant Physiology

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Pea (Pisum safivum L.) lines G2 (dwarf) and NCBl769 (tall) (Sn Hr) produce flowers and fruit under long (LD) or short (SD) days, but senesce only under LD. Endogenous gibberellin (CA) levels were inversely correlated with photoperiod (over 9-1 8 h) and senescence: CA,, was 3-fold and CA, was 10-to 11-fold higher in flowering SD C2 shoots, and the vegetative tissues within the SD apical bud contained 4-fold higher levels of CA,,, as compared with the LD tissues. Prefloral C2 plants under both photoperiods had CA, and CA,, levels similar to the flowering plants under LD. Levels of indole-3-acetic acid (IAA) were similar in C2 shoots in LD or SD; SD apical bud vegetative tissues had a slightly higher IAA content. Young floral buds from LD plants had twice as much IAA as under SD. In NCB1769 shoots CA, decreased after flower initiation only under LD, which correlated with the decreased growth potential. We suggest that the higher CA, content of G2 and NCB1769 plants under SD Under LD conditions fruit development in G2 pea plants results in apical senescence, but under SD conditions apical growth continues, despite the presence of a large number of fruit. This is dependent on the presence of dominant alleles at the Sn and Hr genetic loci. The photoperiodic response of G2 plants is nonphotosynthetic and quantitative, such that a brief exposure of light during the night does not reverse its SD growth habit (Proebsting et al., 1976). The growth rate of developing seeds on G2 plants is more rapid under LD than under SD conditions, which is indicative of a greater nutrient drain exerted on LD plants

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“…There is considerable evidence in support of this hypothesis, and it is beginning to look as though the mechanism of tumor induction in this system is similar to that by which axillary buds are released from the dominance of the apical meristem. First, it has been demonstrated that correlative inhibition of axillary buds diminishes as a plant gets older (18). Tumors appear most frequently on mature Nicotiana hybrids during and after the flowering period when growth of the shoot apex is reduced (15).…”

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Endogenous Levels of Auxin and Tumorigenesis in a Nicotiana Amphiploid

Ames¹

1974

Plant Physiol.

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Young seedlings of the tumor-prone amphiploid Nicotiana suaveolens X N. langsdorjjii were grown aseptically on nutrient medium in a controlled environment chamber. At regular intervals after the seeds had been sown, the incidence of tumor formation was scored and plants were harvested. Indole-3-acetic acid was extracted, purified, and assayed spectrofluorometrically. A close correlation in time between onset of tumor formation and decline in endogenous level of indole-3-acetic acid was demonstrated.It has been suggested that the trigger for tumor induction in certain Nicotiana hybrids is a reduction in the endogenous level of auxin (5). There is considerable evidence in support of this hypothesis, and it is beginning to look as though the mechanism of tumor induction in this system is similar to that by which axillary buds are released from the dominance of the apical meristem. First, it has been demonstrated that correlative inhibition of axillary buds diminishes as a plant gets older (18). Tumors appear most frequently on mature Nicotiana hybrids during and after the flowering period when growth of the shoot apex is reduced (15). Second, growth of inhibited axillary buds can be stimulated by decapitation of the apical bud, and this loss of apical dominance can be prevented by applying IAA to the cut surface of decapitated plants (27). Decapitation of primary and secondary shoots accelerates tumor formation in Nicotiana, and the appearance of internodal tumors can be suppressed with exogenous IAA (5). Third, triiodobenzoic acid has been shown to break apical dominance in a variety of plants (6,13,20,25,28) While the available evidence supports the suggestion that auxin is involved in the trigger for tumor induction in genetically tumor-conditioned Nicotiana hybrids, a reduction in auxin at potential centers of growth prior to tumor initiation has not been reported. The aim of the present investigation was to study the rate of tumor formation and fluctuations in the endogenous level of IAA with time in young tumor-prone Nicotiana seedlings. MATERIALS AND METHODSSeeds of the amphiploid Nicotiana suaveolens X N. lanigsdorffii were surface-sterilized in a Clorox-Kromet solution for 12 min, and then sown in 125-ml Erlenmeyer flasks on 30 ml of a modified Hildebrandt-Riker nutrient medium (pH 5.3-5.4) which was solidified with 1.0% (w/v) agar (14). Seedlings were grown in a controlled environment chamber at 22 ± 1 C and 60 to 65% relative humidity under 18 hr illumination (1900 -4-150 ft-c). Beginning 11 days after the seeds had been sown, the plants were examined at regular intervals in order to score the incidence of tumor formation as evidenced by visible outgrowth of undifferentiated tissue.In order to determine the endogenous level of IAA, plants were harvested, the roots were removed, and the tops were immediately frozen in liquid nitrogen. The seedlings (3-5 g fresh weight) were ground to a fine powder in a prechilled mortar and pestle. The powdered material was extracted, the extract was purified, ...

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Fruit-induced & apical senescence in Pisum sativum L.

Cited by 73 publications

References 8 publications

Studies on the Behavior of the Senescence Signal in Anoka Soybeans

Studies on the Behavior of the Senescence Signal in Anoka Soybeans

The Control of Apical Bud Growth and Senescence by Auxin and Gibberellin in Genetic Lines of Peas

Endogenous Levels of Auxin and Tumorigenesis in a Nicotiana Amphiploid

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