For my purpose and as a means of understanding these abstract notes I grabbed. The verbiage used of +FR-induced hypocotyl elongation is a fancy way to say shade avoidance. The BR signaling pathway I highlighted is very important. I need to understand shade avoidance theories so I have read this stuff while gently enchanted via some Cali O.
"Brassinosteroid Pathway Is Inhibited by Salt and ABA
We hypothesized that PIF4 and PIF5 action could be inhibited through a change in activity of one of their interaction partners. In NaCl-treated roots, ABA production precedes a reduction of BR signaling [26] and it is known that BR signaling is necessary for +FR-induced hypocotyl elongation to occur [16]. This raises the possibility that during NaCl exposure ABA acts to inhibit BR signals. We tested the effect of brassinazole (BRZ- an inhibitor of BR synthesis) on hypocotyl elongation under +FR light. We found that BRZ, much like both NaCl and ABA, inhibited hypo-cotyl elongation very readily at low concentrations a hibition remained constant as concentrations increased (Fig-ure S4B). Intriguingly, hypocotyl length at this plateau was equal to that of +FR-treated plants grown on saline soil in the absence of BRZ. Furthermore, simultaneous application of ABA, BRZ, and NaCl had no further effect on the hypocotyl length of +FR-treated plants than NaCl treatment alone (Figure S4C), consistent with these compounds converging on the same pathway. Supporting this, application of epi-brassinolide (BL) rescued +FR-induced hypocotyl elongation in NaCl-exposed plants (Figure S4D). Hy-pocotyl length was rescued at low concentrations of epi-BL, upto the extent of +FR-treated control plants grown in the absence of NaCl (Figure S4D). We also observed that epi-BL could not rescue hypocotyl elongation in the yucca 2589 mutant (Fig-ure S4E), which probably indicates that in our conditions, BR-mediated rescue of hypocotyl elongation is auxin dependent.
Soil Salinity Acts through the ABA Pathway Many plant responses to soil salinity are mediated through the hormone abscisic acid (ABA) [11]. We found that transcripts of SAG 29 (an ABA-responsive gene [12]) accumulated to high levels in +NaCl +FR conditions (Figure 2A). This accumulation did not occur in plants lacking four ABA-responsive transcription factors"
Wow, not so sure some of the conclusions but BR signaling research is not so plentiful so we learn from what we can.
