阿拉伯芥麩胺基硫轉移酶 AtGSTU17 突變株耐旱及耐鹽性狀為麩胺基與離層酸共同作用之結果

Abstract

Although glutathione S-transferases (GSTs) are thought to play major roles in oxidative stress metabolism, little is known about the regulatory functions of GSTs. We have reported that GLUTATHIONE S-TRANSFERASE U17 (AtGSTU17, At1g10370) participates in light signaling and might modulate various aspects of development by affecting glutathione (GSH) pools via a coordinated regulation with phyA. Here we provided further evidence to support a negative role of AtGSTU17 in drought and salt stress tolerance. When AtGSTU17 was mutated, plants were more tolerant to drought and salt stresses compared to wild-type (WT, Col-0) plants. In addition, atgstu17 accumulated higher level of GSH and abscisic acid (ABA), and exhibited hyposensitivity to ABA during seed germination, smaller stomatal apertures, a lower transpiration rate, better development of primary and lateral root systems, and longer vegetative growth. To explore how atgstu17 accumulated higher ABA content, we grew WT in the solution containing GSH and found that plants accumulated ABA to a higher extent than plants grown in the absence of GSH, and exhibited the atgstu17 phenotypes. WT plants treated with GSH also demonstrated more tolerant to drought and salt stresses. Furthermore, the effect of GSH on root patterning and drought tolerance was confirmed by growing the atgstu17 in solution containing L-buthionine-(S,R)- sulfoximine (BSO), a specific inhibitor of GSH biosynthesis. In conclusion, the atgstu17 phenotype can be explained by the combined effect of GSH and ABA. Microarray analysis provided evidence that expressions of many genes related to growth and stress inducible transcription factors altered in the atgstu17 mutants. We propose a role of AtGSTU17 in adaptive responses to drought and salt stresses, by functioning as a negative component of stress-mediated signal transduction pathways.