The small GTPase, nucleolar GTP-binding protein 1 (NOG1), has a novel role in plant innate immunity

Abstract

Plant defense responses at stomata and apoplast are the most important early events during plant-bacteria interactions. The key components for the signaling of stomatal defense and nonhost resistance have not been fully characterized. Here we report the newly identified small GTPase, Nucleolar GTP-binding protein 1 (NOG1), functions for plant immunity against bacterial pathogens. Virus-induced gene silencing of NOG1 compromised nonhost resistance in N. benthamiana and tomato. Comparative genomic analysis showed that two NOG1 copies are present in all known plant species: NOG1-1 and NOG1-2. Gene downregulation and overexpression studies of NOG1-1 and NOG1-2 in Arabidopsis revealed the novel function of these genes in nonhost resistance and stomatal defense against bacterial pathogens, respectively. Specially, NOG1-2 regulates guard cell signaling in response to biotic and abiotic stimuli through jasmonic acid (JA)- and abscisic acid (ABA)-mediated pathways. The results here provide valuable information on the new functional role of small GTPase, NOG1, in guard cell signaling and early plant defense in response to bacterial pathogens.

Ribosome Biogenesis in Plants: From Functional 45S Ribosomal DNA Organization to Ribosome Assembly Factors

“…GTPase homologs of the yeast and human proteins Nuclear GTPase1(Nug1)/NUCLEOSTEMIN1 (NS1), Nug2/Nucleolar GTPase2 (Nog2), Nog1, and Large Subunit GTPase1 (Lsg1/LSG1) are required for maturation of the pre-60S subunit in Arabidopsis (Im et al, 2011;Weis et al, 2014;Jeon et al, 2015;Zhao et al, 2015;Lee et al, 2017). However, no GTPase homologs have thus far been shown to mediate pre-40S subunit maturation.…”

“…Moreover, homologs of the yeast Nog1 protein have been reported in Nicotiana benthamiana and Arabidopsisplants. The N. benthamiana homolog of Nog1 is required for processing of 35S, 33S, and 27S intermediates (Guo et al, 2018), while Arabidopsis NOG1-1 and NOG1-2 are involved in biotic and abiotic stress responses (Lee et al, 2017).…”

Involvement of nonhost resistance genes in disease resistance plausible for future crop improvement

“…Another newly identified GTPase gene NUCLEOLAR GTP-BINDING PROTEIN 1 (NOG1) involves in NHR against bacterial pathogens (Lee et al 2017b) through stomatal defence. The virus induced silencing of NOG1 gene in nonhost plants tomato and N. benthamiana causes compromised in resistance to nonhost pathogens P. syringae pv.…”

“…tomato T 1 respectively (Lee et al 2017b). Two copies of NOG1 (NOG1-1, NOG1-2) in Arabidopsis helps in stomata defence and NHR against bacterial pathogens (Lee et al 2017b).…”

Essential role of NbNOG1 in ribosomal RNA processing

“…Remarkably, a recent study also implicated NOG1 in plant anti‐microbial defense (Lee et al ). It would be interesting to determine whether this defense role of plant NOG1 is related to ribosome biogenesis.…”