Comprehensive study of excess phosphate response reveals ethylene mediated signaling that negatively regulates plant growth and development

Abstract

Excess Phosphorus (P) in agriculture is causing serious environmental problems like eutrophication of lakes and rivers. Unlike the enormous information available for phosphate starvation response (P0), very few information is available for the effect of excess phosphate Pi on plants. Characterization of Excess Phosphate Response (EPiR) is essential for designing strategies to increase phosphate accumulation and tolerance. We show a significant modulation in the root developmental plasticity under the increasing supply of excess Pi. An excess supply of 20 mM Pi (P20) produces a shallow root system architecture (RSA), reduces primary root growth, root apical meristem size, and meristematic activity in Arabidopsis. The inhibition of primary root growth and development is indeterminate in nature and caused by the decrease in number of meristematic cortical cells due to EPiR. Significant changes occurred in metal nutrients level due to excess Pi supply. A comparative microarray investigation of the EPiR response reveals a modulation in ethylene biosynthesis and signaling, metal ions deficiency response, and root development related genes. We used ethylene-insensitive or sensitive mutants to provide more evidence for ethylene-mediated signaling. A new role of EPiR in regulating the developmental responses of plants mediated by ethylene has been demonstrated.

Transcriptional dynamics of bread wheat in response to nitrate and phosphate supply reveal functional divergence of genetic factors involved in nitrate and phosphate signaling

“…Congruent with our observations, previous studies have reported up-regulation of 315 nicotianamine synthase genes in response to nitrate supply in Arabidopsis (R. Wang et al 316 2000; R. Wang et al 2003). However, in the study by (Shukla et al 2017 After 2 h of N supply in the absence of P (pN treatment at 2 h), the over-represented GO 337 terms in the differentially expressed gene set were related to hormonal regulation ("cytokinin 338 metabolism", "response to auxin stimulus") ( Table 1, Table S3). Specifically, the genes that 339 were up-regulated and assigned to "cytokinin metabolism" GO category at 2 h in response 340 to pN treatment were identified as cytokinin oxidase in wheat (Table S3).…”

“…Up-regulation of nicotianamine synthase genes have been 600 reported in response to nitrate supply which has been thought to be a response to facilitate 601 transport of Fe required for synthesis of nitrate assimilatory enzymes such as nitrate 602 reductase and nitrite reductase (R. Wang et al 2003). While nicotianamine synthase gene 603 NAS3 was induced under P starvation (Bournier et al 2013), NAS2 was up-regulated under 604 excess P condition (Shukla et al 2017). Therefore, nitrate or phosphate treatments trigger 605 changes in the nicotianamine levels which may lead to precise regulation of metal ion 606 transport.…”

Integrative analysis of hexaploid wheat roots identifies signature components during iron starvation

“…Earlier studies have suggested that changes in the root system and Fe supply not only affect the Fe accumulation capacity but also impact the uptake of other nutrients such as Zn, Cd, etc. (Sperotto et al , 2012; Shukla et al , 2017). Therefore, the effect of Fe starvation stress on the uptake of Zn, Mn, Cu, and Mg in wheat undergoing Fe stress was studied (Table 1).…”

Cyanide produced with ethylene by ACS and its incomplete detoxification by β-CAS in mango inflorescence leads to malformation

“…The comparatively higher level of methionine in MI than HI of mango plants suggest increased rate of cyanide and ethylene production in the malformed tissues under the hypersensitive stress response. Thus, continuous synthesis of cyanide and ethylene liberates considerable inorganic phosphorous (PPi and Pi) in the step catalyzed by SAM synthetase 25 , and excessive Pi causes the formation of shallow roots reducing plant growth and meristematic activity 48 . Similarly, we have found higher phosphorus concentrations in MI than HI suggesting another link to malformation.…”