High impact information on SAG12

• Expression of the cytokinin-synthesizing isopentenyl transferase enzyme under the control of the Arabidopsis (Arabidopsis thaliana) SAG12 senescence-inducible promoter reverses the normal abortion of the lower floret from a maize (Zea mays) spikelet [1].
• Vacuolar compartments associated with leaf senescence and the subcellular localization of the senescence-specific cysteine-protease SAG12 (senescence-associated gene 12) were studied using specific fluorescent markers, the expression of reporter genes, and the analysis of high-pressure frozen/freeze-substituted samples [2].
• Expression of senescence-associated genes 12 (SAG12), a marker gene for senescence, was induced in the hmg1 mutant at an earlier stage than in the WT [3].
• An ipt gene under control of the senescence-specific SAG12 promoter from Arabidopsis (P(SAG12)-IPT) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (Lactuca sativa L. cv Evola) homozygous for the transgene [4].
• Senescence-induced expression of the cysteine protease gene SAG12, for example, was conditional on the presence of SA, together with another unidentified senescence-specific factor [5].

Biological context of SAG12

• In this study it is shown that the expression of SAG12 is specifically activated by developmentally controlled senescence pathways but not by stress- or hormone-controlled pathways [6].
• Identification of a promoter region responsible for the senescence-specific expression of SAG12 [6].
• Real-time RT-PCR studies were performed to quantify ipt and SAG12 gene expression [7].

Associations of SAG12 with chemical compounds

• SAG12, an Arabidopsis gene encoding a cysteine protease, is expressed only in senescent tissues [6].
• Using SAG12 as a molecular marker for the study of developmental senescence, we show that cytokinin, auxin, and sugars can repress developmental senescence at the molecular level [6].
• Most importantly, the senescence-specific gene SAG12, which was previously thought to be sugar-repressible, was induced over 900-fold by glucose [8].
• Senescence-associated processes were successfully induced by natural aging, by jasmonate methyl ester and by darkness in whole plants and detached leaves, as demonstrated by the expression of the senescence marker genes SAG12 and SAG13 [9].

Other interactions of SAG12

• The SAG12 promoter is very specific to senescing leaves, whereas the SAG13 promoter is expressed in mature leaves prior to the onset of visible senescence and its expression increases in senescing leaves [10].
• The mRNA level of WRKY53 increased substantially within the rosette leaves of a 6-week-old plant before the expression of SAG12 became detectable, was constant in all leaves of a 7-week-old plant and decreased again in 8-week-old plants [11].

References