TY - JOUR
T1 - Overexpression of atbbd1, arabidopsis bifunctional nuclease, confers drought tolerance by enhancing the expression of regulatory genes in aba-mediated drought stress signaling
AU - Mahmudul Huque, A. K.M.
AU - So, Wonmi
AU - Noh, Minsoo
AU - You, Min Kyoung
AU - Shin, Jeong Sheop
N1 - Funding Information:
Funding: This work was supported by a grant (2019R1F1A1060014) from the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT, Republic of Korea. This work was also partially supported by Korea University.
Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2021/3/2
Y1 - 2021/3/2
N2 - Drought is the most serious abiotic stress, which significantly reduces crop productivity. The phytohormone ABA plays a pivotal role in regulating stomatal closing upon drought stress. Here, we characterized the physiological function of AtBBD1, which has bifunctional nuclease ac-tivity, on drought stress. We found that AtBBD1 localized to the nucleus and cytoplasm, and was expressed strongly in trichomes and stomatal guard cells of leaves, based on promoter:GUS con-structs. Expression analyses revealed that AtBBD1 and AtBBD2 are induced early and strongly by ABA and drought, and that AtBBD1 is also strongly responsive to JA. We then compared pheno-types of two AtBBD1-overexpression lines (AtBBD1-OX), single knockout atbbd1, and double knockout atbbd1/atbbd2 plants under drought conditions. We did not observe any phenotypic difference among them under normal growth conditions, while OX lines had greatly enhanced drought toler-ance, lower transpirational water loss, and higher proline content than the WT and KOs. Moreover, by measuring seed germination rate and the stomatal aperture after ABA treatment, we found that AtBBD1-OX and atbbd1 plants showed significantly higher and lower ABA-sensitivity, respectively, than the WT. RNA sequencing analysis of AtBBD1-OX and atbbd1 plants under PEG-induced drought stress showed that overexpression of AtBBD1 enhances the expression of key regulatory genes in the ABA-mediated drought signaling cascade, particularly by inducing genes related to ABA biosynthesis, downstream transcription factors, and other regulatory proteins, conferring At-BBD1-OXs with drought tolerance. Taken together, we suggest that AtBBD1 functions as a novel positive regulator of drought responses by enhancing the expression of ABA-and drought stress-responsive genes as well as by increasing proline content.
AB - Drought is the most serious abiotic stress, which significantly reduces crop productivity. The phytohormone ABA plays a pivotal role in regulating stomatal closing upon drought stress. Here, we characterized the physiological function of AtBBD1, which has bifunctional nuclease ac-tivity, on drought stress. We found that AtBBD1 localized to the nucleus and cytoplasm, and was expressed strongly in trichomes and stomatal guard cells of leaves, based on promoter:GUS con-structs. Expression analyses revealed that AtBBD1 and AtBBD2 are induced early and strongly by ABA and drought, and that AtBBD1 is also strongly responsive to JA. We then compared pheno-types of two AtBBD1-overexpression lines (AtBBD1-OX), single knockout atbbd1, and double knockout atbbd1/atbbd2 plants under drought conditions. We did not observe any phenotypic difference among them under normal growth conditions, while OX lines had greatly enhanced drought toler-ance, lower transpirational water loss, and higher proline content than the WT and KOs. Moreover, by measuring seed germination rate and the stomatal aperture after ABA treatment, we found that AtBBD1-OX and atbbd1 plants showed significantly higher and lower ABA-sensitivity, respectively, than the WT. RNA sequencing analysis of AtBBD1-OX and atbbd1 plants under PEG-induced drought stress showed that overexpression of AtBBD1 enhances the expression of key regulatory genes in the ABA-mediated drought signaling cascade, particularly by inducing genes related to ABA biosynthesis, downstream transcription factors, and other regulatory proteins, conferring At-BBD1-OXs with drought tolerance. Taken together, we suggest that AtBBD1 functions as a novel positive regulator of drought responses by enhancing the expression of ABA-and drought stress-responsive genes as well as by increasing proline content.
KW - ABA response
KW - Abiotic stress
KW - Arabidopsis thaliana
KW - AtBBD1
KW - DUF151 domain
KW - Drought tolerance
KW - Stomatal movement
UR - http://www.scopus.com/inward/record.url?scp=85102348001&partnerID=8YFLogxK
U2 - 10.3390/ijms22062936
DO - 10.3390/ijms22062936
M3 - Article
C2 - 33805821
AN - SCOPUS:85102348001
SN - 1661-6596
VL - 22
SP - 1
EP - 21
JO - International Journal of Molecular Sciences
JF - International Journal of Molecular Sciences
IS - 6
M1 - 2936
ER -