8 research outputs found
Solanum lycopersicon Mill. and Nicotiana benthamiana L. under high light show distinct responses to anti-oxidative stress
Two experimentally important species, Solanum lycopersicon Mill. and Nicotiana
benthamiana L., were propagated in vitro under low light (50 mmolm 2 s 1) and
transferred to HL (200 mmolm 2 s 1) under a protocol previously developed for
grapevine and chestnut. Compared with photooxidative stress parameters already
tested in those species, imaging of hydrogen peroxide and superoxide revealed
an accumulation on d2â3 and d6 in S. lycopersicon and d1â2 and d5â7 in
N. benthamiana. SOD, CAT and APX activities matched ROS accumulation. The
expression of the respective transcripts showed a significant increase on d1 in
S. lycopersicon while in N. benthamiana a bimodal pattern was found, with peaks on
d2 and d7. These results, together with the relative timing of root expansion and
new leaf emergence, indicate that these two apparently similar species display
different strategies when responding to light stress, evidencing further the
uniqueness of the response of each species. The behaviour of N. benthamiana falls
closely into the pattern already reported for wood species including grapevin
Quantification of endogenous levels of IAA, IAAsp and IBA in micro-propagated shoots of hybrid chestnut pre-treated with IBA
Endogenous levels of indole-3-acetic acid (IAA),
indole-3-acetylaspartic acid (IAAsp) and indole-3-butyric
acid (IBA) were measured during the first 8 d of in vitro
rooting of rootstock from the chestnut âM3â hybrid by high
performance liquid chromatography (HPLC). Rooting was
induced either by dipping the basal ends of the shoots into a
4.92-mM IBA solution for 1 min or by sub-culturing the
shoots on solid rooting medium supplemented with 14.8-
ÎŒM IBA for 5 d. For root development, the induced shoots
were transferred to auxin-free solid medium. Auxins were
measured in the apical and basal parts of the shoots by
means of HPLC. Endogenous levels of IAA and IAAsp
were found to be greater in IBA-treated shoots than in
control shoots. In extracts of the basal parts of the shoots,
the concentration of free IAA showed a significant peak 2 d
after either root inductive method and a subsequent gradual
decrease for the remainder of the time course. The
concentration of IAAsp peaked at day 6 in extracts of the
basal parts of shoots induced with 14.8-ÎŒM IBA for 5 d,
whereas shoots induced by dipping showed an initial
increase until day 2 and then remained stable. In extracts
from basal shoot portions induced by dipping, IBA
concentration showed a transient peak at day 1 and a plateau between day 2 and 4, in contrast to the profile of
shoots induced on auxin-containing medium, which
showed a significant reduction between 4 and 6 d after
transferred to auxin-free medium. All quantified auxins
remained at a relatively low level, virtually constant, in
extracts from apical shoot portions, as well as in extracts
from control non-rooting shoots. In conclusion, the natural
auxin IAA is the signal responsible for root induction,
although it is driven by exogenous IBA independently of
the adding conditions
Archived Relations: Repression, Rehabilitation and the Secret Life of Documents in Mongolia
Present General Status of Understanding of Heteropoly Electrolytes and a Tracing of Some Major Highlights in the History of Their Elucidation
Regulation of seedling growth by ethylene and the ethylene-auxin crosstalk
This review highlights that the auxin gradient, established by local auxin biosynthesis and transport, can be controlled by ethylene, and steers seedling growth. A better understanding of the mechanisms in Arabidopsis will increase potential applications in crop species.
In dark-grown Arabidopsis seedlings, exogenous ethylene treatment triggers an exaggeration of the apical hook, the inhibition of both hypocotyl and root elongation, and radial swelling of the hypocotyl. These features are predominantly based on the differential cell elongation in different cells/tissues mediated by an auxin gradient. Interestingly, the physiological responses regulated by ethylene and auxin crosstalk can be either additive or synergistic, as in primary root and root hair elongation, or antagonistic, as in hypocotyl elongation. This review focuses on the crosstalk of these two hormones at the seedling stage. Before illustrating the crosstalk, ethylene and auxin biosynthesis, metabolism, transport and signaling are briefly discussed