Affiliation:
1. College of Horticulture Hunan Agricultural University 410128 Changsha China
2. National Center for Citrus Improvement 410128 Changsha China
3. Institute of Horticulture, Hunan Academy of Agricultural Science 410125 Changsha China
Abstract
Summary
Plenty of rainfall but unevenly seasonal distribution happens regularly in southern China. Seasonal drought from summer to early autumn leads to citrus fruit acidification, but how seasonal drought regulates citrate accumulation remains unknown.
Herein, we employed a set of physiological, biochemical, and molecular approaches to reveal that CsABF3 responds to seasonal drought stress and modulates citrate accumulation in citrus fruits by directly regulating CsAN1 and CsPH8.
Here, we demonstrated that irreversible acidification of citrus fruits is caused by drought lasting for > 30 d during the fruit enlargement stage. We investigated the transcriptome characteristics of fruits affected by drought and corroborated the pivotal roles of a bHLH transcription factor (CsAN1) and a P3A‐ATPase gene (CsPH8) in regulating citrate accumulation in response to drought. Abscisic acid (ABA)‐responsive element binding factor 3 (CsABF3) was upregulated by drought in an ABA‐dependent manner. CsABF3 activated CsAN1 and CsPH8 expression by directly and specifically binding to the ABA‐responsive elements (ABREs) in the promoters and positively regulated citrate accumulation.
Taken together, this study sheds new light on the regulatory module ABA‐CsABF3‐CsAN1‐CsPH8 responsible for citrate accumulation under drought stress, which advances our understanding of quality formation of citrus fruit.
Funder
National Key Research and Development Program of China
Earmarked Fund for China Agriculture Research System
Natural Science Foundation of Hunan Province
National Natural Science Foundation of China