Timing of invasive pollen deposition influences pollen tube growth and seed set in a native plant

2016 ◽  
Vol 18 (6) ◽  
pp. 1701-1711 ◽  
Author(s):  
Daniela Bruckman ◽  
Diane R. Campbell
2006 ◽  
Vol 33 (1) ◽  
pp. 1 ◽  
Author(s):  
Catherine M. Cox ◽  
Stephen M. Swain

In Arabidopsis, as in the majority of flowering plants, developing seeds promote fruit growth. One method to investigate this interaction is to use plants with reduced seed set and determine the effect on fruit growth. Plants homozygous for a transgene designed to ectopically express a gene encoding a gibberellin-deactivating enzyme exhibit reduced pollen tube elongation, suggesting that the plant hormone gibberellin is required for this process. Reduced pollen tube growth causes reduced seed set and decreased silique (fruit) size, and this genotype is used to explore the relationship between seed set and fruit elongation. A detailed analysis of seed set in the transgenic line reveals that reduced pollen tube growth decreases the probability of each ovule being fertilised. This effect becomes progressively more severe as the distance between the stigma and the ovule increases, revealing the complex biology underlying seed fertilisation. In terms of seed-promoted fruit growth, major localised and minor non-localised components that contribute to final silique length can be identified. This result demonstrates that despite the relatively small size of the fruit and associated structures, Arabidopsis can be used as a model to investigate fundamental questions in fruit physiology.


2014 ◽  
Vol 70 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Ettore Pacini ◽  
Massimo Nepi

The effects of pistil age on pollen tube growth, fruit development and seed set were studied in <em>Cucurbita pepo</em> L., the flower of which opens for only six hours. Stigma receptivity lasts four days, from one day before until two days after anthesis. Style receptivity lasts three days, from the day before to the day after anthesis. Ovule receptivity lasts two days: the day of anthesis and the day before. The rate of pollen tube growth varies in different parts of the pistil and in relation to pistil age. In the stigmatic and stylar region, the tubes grow faster if pollination occurs the day before anthesis; in the ovary they grow faster when pollination occurs at anthesis. In the receptacle region, where the transmitting tissue is reduced, the growth rate decreases independently of the time of pollination. The fruits are larger and heavier with more seeds when pollination occurs at anthesis. There is a positive correlation between seed number and fruit weight when pollination occurred at anthesis and the day before.


1992 ◽  
Vol 117 (2) ◽  
pp. 328-331 ◽  
Author(s):  
Robert D. Marquard

In vivo pollen tube growth of pecan [Carya illinoinensis (Wangenh.) K. Koch] was estimated to be ≈ 150 μm·hour-1 from 3 to 8 hours postpollination. Pollen tubes averaged 47, 194, 405, and 946 μm after 2, 3, 4, and 8 hours postpollination, respectively. Pollen tube growth was strongly influenced by temperature, and in vitro studies demonstrated pollen germination and tube growth were optimal at 27C for `Cape Fear' pecan. In in vivo studies, tubes of cross-pollen did not grow significantly faster than tubes of self-pollen. Pollen tubes of water hickory [C. aquatica (Michx. f.) Nutt.] grew significantly faster than those of C. illinoinensis. Bitternut [C. cordiformis (Wangenh.) K. Koch] and mockernut hickory (C. tomentosa Nutt.) pollen tubes grew significantly slower on pecan stigmas than did pecan pollen. Pollen arriving first on the stigma has a decided advantage for fertilization success of pecan. The fertilization success rate of pecan pollen arriving 24 hours after first pollen arrival was <3%.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Weifeng Chen ◽  
Zhengcao Xiao ◽  
Yule Wang ◽  
Jinxiao Wang ◽  
Rui Zhai ◽  
...  

AbstractFlavonoids play important roles in regulating plant growth and development. In this study, three kaempferol 3-O-glycosides were identified and mainly accumulated in flowers but not in leaves or fruits of Malus. In Malus, flower petal color is normally white, but some genotypes have red flowers containing anthocyanin. Anthocyanin biosynthesis appears to be in competition with kaempferol 3-O-glycosides production and controlled by the biosynthetic genes. The white flower Malus genotypes had better-developed seeds than the red flower genotypes. In flowers, the overexpression of MYB10 in Malus domestica enhanced the accumulation of anthocyanin, but decreased that of kaempferol 3-O-glycosides. After pollination the transgenic plants showed slower pollen tube growth and fewer developed seeds. Exogenous application of different flavonoid compounds suggested that kaempferol 3-O-glycosides, especially kaempferol 3-O-rhamnoside, regulated pollen tube growth and seed set rather than cyanidin or quercetin 3-O-glycosides. It was found that kaempferol 3-O-rhamnoside might regulate pollen tube growth through effects on auxin, the Rho of plants (ROP) GTPases, calcium and the phosphoinositides signaling pathway. With the inhibition of auxin transport, the transcription levels of Heat Shock Proteins (HSPs) and ROP GTPases were downregulated while the levels were not changed or even enhanced when blocking calcium signaling, suggesting that HSPs and ROP GTPases were downstream of auxin signaling, but upstream of calcium signaling. In summary, kaempferol glycoside concentrations in pistils correlated with auxin transport, the transcription of HSPs and ROP GTPases, and calcium signaling in pollen tubes, culminating in changes to pollen tube growth and seed set.


HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 497a-497 ◽  
Author(s):  
Neil O. Anderson ◽  
Peter D. Ascher

Lythrum species (Lythraceae), found both in the Old and New Worlds, possess heterostyly (macroscopic differences in anther and style lengths). SI is linked with heterostyly in tristylous L. salicaria, allowing for visual identification of compatibility relationships. Five Minnesota populations of distylous L. alatum (short & long styles/anthers) were examined for fertility and linkage between distyly and SI. Pollen was not inhibited from germination, stigmatic penetration, or stylar growth in compatible crosses. Average cross-compatible seed set for each population was 7-33 seeds/capsule for short- and 27-69 for long-styled plants. With the exception of the Iron Horse Prairie population, there were no significant differences in mean seed set/capsule between genotypes, style morphs, or their interaction for compatible crosses. Zero self seed set predominated, although 0.8±1.8 seeds/capsule were produced by short styles and 1.2 ±2.3 by long styles from Iron Horse Prairie. In those individuals that were SI, pollen tube growth was inhibited following self pollinations.


2001 ◽  
Vol 79 (12) ◽  
pp. 1439-1448 ◽  
Author(s):  
Jeannie Chari ◽  
Paul Wilson

Speciation involves the formation of reproductive isolating mechanisms such as a difference in pollinators, incompatibility between pollen tubes and stylar tissue, hybrid seed abortion, or poor growth of hybrid seedlings. We studied reproductive isolating mechanisms in naturally sympatric populations of Penstemon spectabilis Thurber and Penstemon centranthifolius (Benth.) Benth. where F1 hybrids occurred at very low frequency. We compared conspecific crosses, backcrosses, and heterospecific crosses in terms of pollen grain germination, pollen tube growth, fruit set, seed set, and offspring performance. We found several postpollination barriers to hybridization. When P. spectabilis was the ovule parent, the lack of natural hybridization was partially explained by the presence of two isolating factors: reduced pollen tube growth and reduced seed set. When P. centranthifolius was the recipient, the barrier to hybridization was nearly 100% effective and occurred primarily at the stages of pollen grain germination and fruit set. The success of backcrossing was generally intermediate between conspecific and heterospecific crossing. For these two species, it is likely that partial pollinator specificity in addition to strong postpollination reproductive isolating mechanisms contribute to maintaining the species boundary.Key words: speciation, hybridization, introgression, Penstemon, reproductive isolating barriers.


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