1. Hormonal control of sulfate uptake and assimilation
Anna Koprivova, Stanislav Kopriva Plant Mol Biol. 2016 Aug;91(6):617-27. doi: 10.1007/s11103-016-0438-y. Epub 2016 Jan 25.
Plant hormones have a plethora of functions in control of plant development, stress response, and primary metabolism, including nutrient homeostasis. In the plant nutrition, the interplay of hormones with responses to nitrate and phosphate deficiency is well described, but relatively little is known about the interaction between phytohormones and regulation of sulfur metabolism. As for other nutrients, sulfate deficiency results in modulation of root architecture, where hormones are expected to play an important role. Accordingly, sulfate deficiency induces genes involved in metabolism of tryptophane and auxin. Also jasmonate biosynthesis is induced, pointing to the need of increase the defense capabilities of the plants when sulfur is limiting. However, hormones affect also sulfate uptake and assimilation. The pathway is coordinately induced by jasmonate and the key enzyme, adenosine 5'-phosphosulfate reductase, is additionally regulated by ethylene, abscisic acid, nitric oxid, and other phytohormones. Perhaps the most intriguing link between hormones and sulfate assimilation is the fact that the main regulator of the response to sulfate starvation, SULFATE LIMITATION1 (SLIM1) belongs to the family of ethylene related transcription factors. We will review the current knowledge of interplay between phytohormones and control of sulfur metabolism and discuss the main open questions.
2. Virus-induced gene silencing in tomato
Yule Liu, Michael Schiff, S P Dinesh-Kumar Plant J. 2002 Sep;31(6):777-86. doi: 10.1046/j.1365-313x.2002.01394.x.
We have previously demonstrated that a tobacco rattle virus (TRV)-based vector can be used in virus-induced gene silencing (VIGS) to study gene function in Nicotiana benthamiana. Here we show that recombinant TRV infects tomato plants and induces efficient gene silencing. Using this system, we suppressed the PDS, CTR1 and CTR2 genes in tomato. Suppression of CTR1 led to a constitutive ethylene response phenotype and up-regulation of an ethylene response gene, CHITINASE B. This phenotype is similar to Arabidopsis ctr1 mutant plants. We have constructed a modified TRV vector based on the GATEWAY recombination system, allowing restriction- and ligation-free cloning. Our results show that tomato expressed sequence tags (ESTs) can easily be cloned into this modified vector using a single set of primers. Using this vector, we have silenced RbcS and an endogenous gene homologous to the tomato EST cLED3L14. In the future, this modified vector system will facilitate large-scale functional analysis of tomato ESTs.
3. Ethylene regulates sulfur acquisition by regulating the expression of sulfate transporter genes in oilseed rape
Musa Al Murad, Kaukab Razi, Lincy Kirubhadharsini Benjamin, Jeong Hyun Lee, Tae Hwan Kim, Sowbiya Muneer Physiol Plant. 2021 Apr;171(4):533-545. doi: 10.1111/ppl.13157. Epub 2020 Jul 28.
To manage nutrient deficiencies, plants develop both morphological and physiological responses. The studies on the regulation of these responses are limited; however, certain hormones and signaling components have been largely implicated. Several studies depicted ethylene as a regulator of the response of some nutrient deficiencies like iron, phosphorous and potassium. The present study focused on the response of sulfur in the presence and absence of ethylene. The experiments were performed in hydroponic nutrient media, using oilseed rape grown with or without sulfur deficiency and ethylene treatments for 10 days. The ACC oxidase and ACC synthase were observed significantly reduced in sulfur-deficient plants treated with ethylene compared to control. The biomass and photosynthetic parameters, including the expression of multicomplex thylakoidal proteins showed a significant increase in sulfur deficient plants supplemented with ethylene. The enzymes related to sulfur regulation such as sulfate adenyltransferase, glutamine synthetase and O-acetylserine (thiol)lyase also showed similar results as shown by the morphological data. The relative expression of the sulfur transporter genes BnSultr1, 1, BnSultr1, 2, BnSultr4,1, BnSultr 4,2, ATP sulfurylase and OASTL increased in sulfur-deficient plants, whereas their expression decreased when ethylene was given to the plants. Fe and S nutritional correlations are already known; therefore, Fe-transporters like IRT1 and FRO1 were also evaluated, and similar results as for the sulfur transporter genes were observed. The overall results indicated that ethylene regulates sulfur acquisition by regulating the expression of sulfur transporter genes in oilseed rape (Brassica napus).