Abstract
In flowering plants, pollination, pollen tube growth, and fertilization are regarded as the first hierarchical processes of producing offspring. However, their independent contributions to fruit set and development remain unclear. In this study, we examined the effect of three different types of pollen, intact pollen (IP), soft X-ray-treated pollen (XP) and dead pollen (DP), on pollen tube growth, fruit development and gene expression in "Micro-Tom" tomato. Normal germination and pollen tube growth were observed in flowers pollinated with IP; pollen tubes started to penetrate the ovary at 9 h after pollination, and full penetration was achieved after 24 h (IP24h), resulting in ~94% fruit set. At earlier time points (3 and 6 h after pollination; IP3h and IP6h, respectively), pollen tubes were still in the style, and no fruit set was observed. Flowers pollinated with XP followed by style removal after 24 h (XP24h) also demonstrated regular pollen tubes and produced parthenocarpic fruits with ~78% fruit set. As expected, DP could not germinate and failed to activate fruit formation. Histological analysis of the ovary at 2 days after anthesis (DAA) revealed that IP and XP comparably increased cell layers and cell size; however, mature fruits derived from XP were significantly smaller than those derived from IP. Furthermore, there was a high correlation between seed number and fruit size in fruit derived from IP, illustrating the crucial role of fertilization in the latter stages of fruit development. RNA-Seq analysis was carried out in ovaries derived from IP6h, IP24h, XP24h and DP24h in comparison with emasculated and unpollinated ovaries (E) at 2 DAA. The results revealed that 65 genes were differentially expressed (DE) in IP6h ovaries; these genes were closely associated with cell cycle dormancy release pathways. Conversely, 5062 and 4383 DE genes were obtained in IP24h and XP24h ovaries, respectively; top enriched terms were mostly associated with cell division and expansion in addition to the 'plant hormone signal transduction' pathway. These findings indicate that full penetration of pollen tubes can initiate fruit set and development independently of fertilization, most likely by activating the expression of genes regulating cell division and expansion.
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Claims 15
Claim · model-written summary
Intact pollen germinated normally and tubes penetrated the ovary at 9 h and fully by 24 h.
- Taxon
- tomato
Solanum lycopersicumt0 - Treatment
- IPe0
- Outcome
- Normal germination and pollen tube growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Normal germination and pollen tube growth were observed in flowers pollinated with IP; pollen tubes started to penetrate the ovary at 9 h after pollination, and full penetration was achieved after 24 h (IP24h)”
t0“tomato”
Claim · model-written summary
Intact pollen at 24 h produced about 94% fruit set.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- IP24he0
- Outcome
- fruit sete0
- Value
- ~94%e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“full penetration was achieved after 24 h (IP24h), resulting in ~94% fruit set”
t0“tomato”
Claim · model-written summary
At 3 and 6 h pollen tubes remained in the style and fruit did not set.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- IP3h and IP6he0
- Outcome
- no fruit sete0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At earlier time points (3 and 6 h after pollination; IP3h and IP6h, respectively), pollen tubes were still in the style, and no fruit set was observed.”
t0“tomato”
Claim · model-written summary
XP pollen at 24 h produced normal tubes and parthenocarpic fruit with about 78% set.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- XP followed by style removal after 24 he0
- Outcome
- fruit sete0
- Value
- ~78%e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Flowers pollinated with XP followed by style removal after 24 h (XP24h) also demonstrated regular pollen tubes and produced parthenocarpic fruits with ~78% fruit set.”
t0“tomato”
Claim · model-written summary
Dead pollen did not germinate or activate fruit formation.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- DPe0
- Outcome
- fruit formatione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DP could not germinate and failed to activate fruit formation”
t0“tomato”
Claim · model-written summary
Intact pollen increased ovary cell layers and cell size at 2 DAA.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- IPe0
- Outcome
- cell layers and cell sizee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IP and XP comparably increased cell layers and cell size”
t0“tomato”
Claim · model-written summary
XP increased ovary cell layers and cell size comparably to intact pollen.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- XPe0
- Outcome
- cell layers and cell sizee0
- Direction
- increasede0
- Comparator
- IPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IP and XP comparably increased cell layers and cell size”
t0“tomato”
Claim · model-written summary
Mature XP fruit was significantly smaller than intact pollen fruit.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- XPe0
- Outcome
- mature fruitse0
- Direction
- smallere0
- Comparator
- IPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mature fruits derived from XP were significantly smaller than those derived from IP”
t0“tomato”
Claim · model-written summary
Seed number correlated strongly with size of intact pollen fruit.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- seede0
- Outcome
- fruit sizee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was a high correlation between seed number and fruit size in fruit derived from IP”
t0“tomato”
Claim · model-written summary
IP6h ovaries had 65 differentially expressed genes.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- ovariese0
- Outcome
- genes were differentially expressede0
- Value
- 65 genese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“65 genes were differentially expressed (DE) in IP6h ovaries”
t0“tomato”
Claim · model-written summary
Genes differentially expressed at IP6h were associated with cell cycle dormancy release.
- Taxon
- tomatoSolanum lycopersicumt0
- Gene
- these genese0
- Outcome
- cell cycle dormancy release pathwayse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these genes were closely associated with cell cycle dormancy release pathways”
t0“tomato”
Claim · model-written summary
IP24h ovaries had 5062 differentially expressed genes.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- ovariese0
- Outcome
- DE genese0
- Value
- 5062e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“5062 and 4383 DE genes were obtained in IP24h and XP24h ovaries, respectively”
t0“tomato”
Claim · model-written summary
XP24h ovaries had 4383 differentially expressed genes.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- ovariese0
- Outcome
- DE genese0
- Value
- 4383e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“5062 and 4383 DE genes were obtained in IP24h and XP24h ovaries, respectively”
t0“tomato”
Claim · model-written summary
Enriched terms for IP24h and XP24h related to cell division, expansion and hormone signaling.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- top enriched termse0
- Qualifier
- cell division and expansione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“top enriched terms were mostly associated with cell division and expansion in addition to the 'plant hormone signal transduction' pathway”
t0“tomato”
Claim · model-written summary
Full pollen tube penetration can initiate fruit set without fertilization, likely by activating genes for cell division and expansion.
- Taxon
- tomatoSolanum lycopersicumt0
- Gene
- genes regulating cell division and expansione0
- Outcome
- fruit set and developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“full penetration of pollen tubes can initiate fruit set and development independently of fertilization, most likely by activating the expression of genes regulating cell division and expansion”
t0“tomato”
The same questions in other papers
radiation · cytology · Solanum lycopersicum (tomato)Positive and negative results
1 in the opposite direction
- negative
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.