Drought Resistance in Qingke Involves a Reprogramming of the Phenylpropanoid Pathway and UDP-Glucosyltransferase Regulation of Abiotic Stress Tolerance Targeting Flavonoid Biosynthesis

Tibetan hulless barley (qingke) is
an important food crop in the
Tibetan plateau. However, it often suffers from drought stress resulting
in reduction of food production because of the extreme plateau environment.
To elucidate the molecular mechanisms underlying the drought resistance
of qingke, the transcriptomic and metabolomic responses of drought-sensitive
(D) and drought-resistant (XL) accessions were characterized in experiments
with a time course design. The phenylpropanoid pathway was reprogrammed
by downregulating the lignin pathway and increasing the biosynthesis
of flavonoids and anthocyanins, and this regulation improved plant
tolerance for drought stress. Besides, flavonoid glycosides have induced
accumulation of metabolites that participated in drought stress resistance. HVUL7H11410 exhibited the activity of wide-spectrum
glucosyltransferase and mediated flavonoid glycosylation to enhance
drought stress resistance. Overall, the findings provide insights
into the regulatory mechanism underlying drought stress tolerance
associated with metabolic reprogramming. Furthermore, the flavonoid-enriched
qingke is more tolerant to drought stress and can be used as a functional
food to benefit human health.