Abstract
Auxins and humic acid (HA) were investigated for their roles in adventitious root induction in azalea microshoots in our previous study. To reveal the regulatory mechanisms of auxins and HA in this process, measurements of the levels of reactive oxygen species (ROS), carbohydrates, and phenolic compounds and gene expression during in vitro root development were performed. During the adventitious root induction process, ROS levels in shoots treated with auxins and HA increased compared to untreated shoots, especially during the earliest period after transfer to the media. Media supplemented with NAA experienced increases in H 2 O 2 contents by 480%and 250%, respectively, after 7 and 14 days of culture. The phenolic compound levels were also enhanced in the shoots treated with auxins and HA, reflecting the different rooting-promoting abilities of both auxins and HA. The highest levels of total phenolic [68.6 mg·g −1 fresh weight (FW)], polyphenolic acids (121.72 μg caffic acid/g FW), and total flavonols (162.42 μg quercetin/g FW) were recorded after 21 days for NAA media, but the maximum levels of anthocyanins (49.76 μg cyanindin/g FW) were recorded after 21 days for IBA medium. Soluble carbohydrate, starch, and soluble protein levels were increased in the shoots treated with all treatments; however, the influence of NAA treatments was stronger than that of other treatments for most investigated parameters. The NAA significantly enhanced soluble carbohydrates by 30%, 37%, and 25%, respectively, at 14, 21, and 28 days compared with untreated microshoots. Expression of the POD1 gene increased in the shoots submitted to HA treatment media. Expression levels of auxin response factors ( ARF s) increased with IBA- and NAA-treated explants, suggesting that ARF s may have diverse regulatory roles in adventitious root induction in evergreen azalea. Moreover, the profiles of the IAA1 , IAA9 , IAA14 , and IAA27 transcripts were analyzed to reveal their roles in the adventitious rooting of evergreen azalea microshoots. These results indicate that auxins and HA promote adventitious root induction in Rhododendron plants through their impact on ROS, carbohydrate contents, phenolic compound levels, and expression levels of different genes related to root development in evergreen azalea plants.
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Claims 16
Claim · model-written summary
Auxin and HA treatments increased shoot ROS during early root induction.
Verbatim
e0“During the adventitious root induction process, ROS levels in shoots treated with auxins and HA increased compared to untreated shoots, especially during the earliest period after transfer to the media.”
t0“Azalea”
Claim · model-written summary
NAA medium increased hydrogen peroxide content by 480% after 7 days.
- Taxon
- Azaleat0
- Treatment
- NAAe0
- Outcome
- H 2 O 2 contentse0
- Direction
- increasese0
- Value
- 480%e0
- Qualifier
- after 7 and 14 days of culturee0
Not reportedComparator
Verbatim
e0“Media supplemented with NAA experienced increases in H 2 O 2 contents by 480%and 250%, respectively, after 7 and 14 days of culture.”
t0“Azalea”
Claim · model-written summary
NAA medium increased hydrogen peroxide content by 250% after 14 days.
- Taxon
- Azaleat0
- Treatment
- NAAe0
- Outcome
- H 2 O 2 contentse0
- Direction
- increasese0
- Value
- 250%e0
- Qualifier
- after 7 and 14 days of culturee0
Not reportedComparator
Verbatim
e0“Media supplemented with NAA experienced increases in H 2 O 2 contents by 480%and 250%, respectively, after 7 and 14 days of culture.”
t0“Azalea”
Claim · model-written summary
Auxin and HA treatments increased phenolic levels in shoots.
- Taxon
- Azaleat0
- Organ / stage
- shootse0
- Treatment
- auxins and HAe0
- Outcome
- phenolic compound levelse0
- Direction
- enhancede0
Not reportedComparator
Verbatim
e0“The phenolic compound levels were also enhanced in the shoots treated with auxins and HA”
t0“Azalea”
Claim · model-written summary
NAA medium yielded the highest total phenolics after 21 days, 68.6 mg per g fresh weight.
Verbatim
e0“The highest levels of total phenolic [68.6 mg·g −1 fresh weight (FW)], polyphenolic acids (121.72 μg caffic acid/g FW), and total flavonols (162.42 μg quercetin/g FW) were recorded after 21 days for NAA media”
t0“Azalea”
Claim · model-written summary
NAA medium yielded the highest polyphenolic acids after 21 days, 121.72 μg caffeic acid per g fresh weight.
Verbatim
e0“The highest levels of total phenolic [68.6 mg·g −1 fresh weight (FW)], polyphenolic acids (121.72 μg caffic acid/g FW), and total flavonols (162.42 μg quercetin/g FW) were recorded after 21 days for NAA media”
t0“Azalea”
Claim · model-written summary
NAA medium yielded the highest total flavonols after 21 days, 162.42 μg quercetin per g fresh weight.
Verbatim
e0“The highest levels of total phenolic [68.6 mg·g −1 fresh weight (FW)], polyphenolic acids (121.72 μg caffic acid/g FW), and total flavonols (162.42 μg quercetin/g FW) were recorded after 21 days for NAA media”
t0“Azalea”
Claim · model-written summary
IBA medium yielded the highest anthocyanin content after 21 days, 49.76 μg cyanindin per g fresh weight.
Verbatim
e0“the maximum levels of anthocyanins (49.76 μg cyanindin/g FW) were recorded after 21 days for IBA medium.”
t0“Azalea”
Claim · model-written summary
Treatments increased soluble carbohydrate, starch, and soluble protein levels.
- Taxon
- Azaleat0
- Treatment
- all treatmentse0
- Outcome
- Soluble carbohydrate, starch, and soluble protein levelse0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Soluble carbohydrate, starch, and soluble protein levels were increased in the shoots treated with all treatments”
t0“Azalea”
Claim · model-written summary
NAA increased soluble carbohydrates by 30% at 14 days relative to untreated shoots.
Verbatim
e0“The NAA significantly enhanced soluble carbohydrates by 30%, 37%, and 25%, respectively, at 14, 21, and 28 days compared with untreated microshoots.”
t0“Azalea”
Claim · model-written summary
NAA increased soluble carbohydrates by 37% at 21 days relative to untreated shoots.
Verbatim
e0“The NAA significantly enhanced soluble carbohydrates by 30%, 37%, and 25%, respectively, at 14, 21, and 28 days compared with untreated microshoots.”
t0“Azalea”
Claim · model-written summary
NAA increased soluble carbohydrates by 25% at 28 days relative to untreated shoots.
Verbatim
e0“The NAA significantly enhanced soluble carbohydrates by 30%, 37%, and 25%, respectively, at 14, 21, and 28 days compared with untreated microshoots.”
t0“Azalea”
Claim · model-written summary
HA treatment increased POD1 expression.
- Taxon
- Azaleat0
- Treatment
- HA treatment mediae0
- Gene
- POD1e0
- Outcome
- Expression of the POD1 genee0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Expression of the POD1 gene increased in the shoots submitted to HA treatment media.”
t0“Azalea”
Claim · model-written summary
IBA treatment increased ARF expression.
- Taxon
- Azaleat0
- Treatment
- IBA-e0
- Gene
- ARF se0
- Outcome
- Expression levels of auxin response factors ( ARF s)e0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Expression levels of auxin response factors ( ARF s) increased with IBA- and NAA-treated explants”
t0“Azalea”
Claim · model-written summary
NAA treatment increased ARF expression.
- Taxon
- Azaleat0
- Treatment
- NAA-treatede0
- Gene
- ARF se0
- Outcome
- Expression levels of auxin response factors ( ARF s)e0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Expression levels of auxin response factors ( ARF s) increased with IBA- and NAA-treated explants”
t0“Azalea”
Claim · model-written summary
The authors concluded auxins and HA promote adventitious rooting through ROS, carbohydrates, phenolics, and gene expression.
- Taxon
- Rhododendron
Rhododendrone0 - Treatment
- auxins and HAe0
- Outcome
- adventitious root inductione0
- Qualifier
- ROS, carbohydrate contents, phenolic compound levels, and expression levels of different genese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results indicate that auxins and HA promote adventitious root induction in Rhododendron plants through their impact on ROS, carbohydrate contents, phenolic compound levels, and expression levels of different genes related to root development in evergreen azalea plants.”