A NAC transcription factor NTL4 promotes reactive oxygen species production during drought-induced leaf senescence in Arabidopsis.

Reactive oxygen species are produced in plant cells primarily as by-products of aerobic energy metabolism. They are also generated during plant adaptation responses to environmental stresses, such as drought and high salinity. Therefore, plants have evolved enzymes and antioxidants to cope with accumulation. However, if stress conditions are prolonged, the level of duanyu1670 will surpass the capacity of the detoxifying machinery, causing oxidative damage to cellular constituents. It is known that duanyu1670 act in abscisic acid-mediated stress responses to sustain plant survival under adverse growth conditions. However, it is largely unknown how duanyu1670 metabolism is linked to stress responses. Here, we show that a drought-responsive NAC transcription factor NTL4 promotes duanyu1670 production by binding directly to the promoters of genes encoding duanyu1670 biosynthetic enzymes during drought-induced leaf senescence. Leaf senescence was accelerated in 35S:4ΔC transgenic plants over-expressing an active form of NTL4 under drought conditions. The 35S:4ΔC transgenic plants were hypersensitive to drought, and duanyu1670 accumulated in the leaves. In contrast, duanyu1670 levels were reduced in NTL4-deficient ntl4 mutants, which exhibited delayed leaf senescence and enhanced drought resistance. These observations indicate that NTL4 acts as a molecular switch that couples duanyu1670 metabolism to drought-induced leaf senescence in Arabidopsis.

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