| RT-PCR |
roots |
up-regulated |
N/A |
Loss of At4 lead to increased shoot Pi content and an increase in the shoot: root Pi ratio under low Pi conditions suggesting At4 affects Pi distribution and plant growth. (Shin et al., 2006) In Arabidopsis, the induced expression of ncRNAs of the IPS1/At4 family during phosphate starvation responses results in the accumulation of the PHO2 mRNA,a target of miR399 (micro-RNA 399). showed that a conserved motif of 23 nt in this ncRNA family is complementary to miR399 but has critical mismatches at positions. Therefore, IPS1/At4 RNAs are not cleaved by miR399 but instead sequester miR399 to inhibit its effect on PHO2 mRNA, in a mechanism known as target mimicry. PHO2 RNA encodes an E2 ubiquitin conjugase-related protein that negatively affects shoot phosphate content and remobilization in an unknown mechanism. (Au et al., 2011) The Arabidopsis pho1 mutant is impaired in its ability to load Pi into the xylem and therefore to translocate Pi to the shoot. At4 transcripts were abundant in pho1 plants receiving both low-Pi and high-Pi fertilizer. These results were observed in two independent experiments. Thus, the At4 transcript is not down-regulated in response to Pi in the pho1 mutant, suggesting that down-regulation is dependent on the translocation of Pi to the shoot. (Burleigh et al., 1999) At4 was designated as the TPSI1/Mt4 family because of their common characteristics. They are up-regulated by P limitation and rapidly down-regulated by supply of P or colonization of mycorrhizal fungi. This fact indicates the possibility that they have an important role on the strategies for low P adaptation, although their physiological function is not still clarified. (Jun et al., 2003) |
16460506, 21525783, 9880366 |
PLNlncRbase
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