Drought stress hinders plant growth and crop yield. Transcription factors
(TF) are known regulators of transcription reprogramming, and expression of
many TF genes including members of the NAC family, is affected by drought.
Venkatesh P. Thirumalaikumar from the Max Planck Institute of Molecular
Plant Physiology focused on the NAC factor JUNGBRUNNEN1 (JUB1) and its role
on drought tolerance in tomato (Solanum lycopersicum).

Expression of tomato JUB1 (SlJUB1) was found to be enhanced by various
abiotic stresses, including drought. On the other hand, inhibiting SlJUB1
expression greatly lowered drought tolerance, alongside increases in ion
leakage and hydrogen peroxide levels, as well as a decrease in the
expression of drought-responsive genes.

Meanwhile, overexpression of AtJUB1 from Arabidopsis thaliana increased
drought tolerance in tomato, alongside a higher relative leaf water content
during drought and reduced hydrogen peroxide levels. The AtJUB1 protein was
previously shown to stimulate expression of DREB2A, a TF involved in drought
responses, and of the DELLA genes GAI and RGL1, which promote stress
tolerance.

These results show that SlJUB1 protein controls the expression of the tomato
orthologs of the DREB2A TF and the DELLA genes. The study revealed JUB1 as a
transcriptional regulator of drought tolerance.

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