Is Photoprotection of PSII One of the Key Mechanisms for Drought Tolerance in Maize?

Nahidah Bashir; Habib-Ur-Rehman Athar; Hazem M Kalaji; Jacek Wróbel; Seema Mahmood; Zafar Ullah Zafar; Muhammad Ashraf

doi:10.3390/ijms222413490

Is Photoprotection of PSII One of the Key Mechanisms for Drought Tolerance in Maize?

Int J Mol Sci. 2021 Dec 16;22(24):13490. doi: 10.3390/ijms222413490.

Authors

Nahidah Bashir^{1

2}, Habib-Ur-Rehman Athar², Hazem M Kalaji^{3

4}, Jacek Wróbel⁵, Seema Mahmood², Zafar Ullah Zafar², Muhammad Ashraf⁶

Affiliations

¹ Department of Botany, The Women University, Multan 66000, Pakistan.
² Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan 60800, Pakistan.
³ Department of Plant Physiology, Institute of Biology, University of Life Sciences SGGW, 02-776 Warsaw, Poland.
⁴ Institute of Technology and Life Sciences, National Research Institute, Falenty, Al. Hrabska 3, 05-090 Raszyn, Poland.
⁵ Department of Bioengineering, West Pomeranian University of Technology in Szczecin, Słowackiego 17, 71-434 Szczecin, Poland.
⁶ Institute of Molecular Biology and Biotechnology, The University of Lahore, Lahore 54590, Pakistan.

Abstract

Drought is one of the most important abiotic stress factors limiting maize production worldwide. The objective of this study was to investigate whether photoprotection of PSII was associated with the degree of drought tolerance and yield in three maize hybrids (30Y87, 31R88, P3939). To do this, three maize hybrids were subjected to three cycles of drought, and we measured the activities of photosystem II (PSII) and photosystem I (PSI). In a second field experiment, three maize hybrids were subjected to drought by withholding irrigation, and plant water status, yield and yield attributes were measured. Drought stress decreased leaf water potential (Ψ_L) in three maize hybrids, and this reduction was more pronounced in hybrid P3939 (-40%) compared to that of 30Y87 (-30%). Yield and yield attributes of three maize hybrids were adversely affected by drought. The number of kernels and 100-kernel weight was the highest in maize hybrid 30Y87 (-56%, -6%), whereas these were lowest in hybrid P3939 (-88%, -23%). Drought stress reduced the quantum yield of PSII [Y(II)], photochemical quenching (qP), electron transport rate through PSII [ETR(II)] and NPQ, except in P3939. Among the components of NPQ, drought increased the Y(NPQ) with concomitant decrease in Y(NO) only in P3939, whereas Y(NO) increased in drought-stressed plants of hybrid 30Y87 and 31R88. However, an increase in cyclic electron flow (CEF) around PSI and Y(NPQ) in P3939 might have protected the photosynthetic machinery but it did not translate in yield. However, drought-stressed plants of 30Y87 might have sufficiently downregulated PSII to match the energy consumption in downstream biochemical processes. Thus, changes in PSII and PSI activity and development of NPQ through CEF are physiological mechanisms to protect the photosynthetic apparatus, but an appropriate balance between these physiological processes is required, without which plant productivity may decline.

Keywords: 100-kernal weight; cyclic electron transport; donor-end limitations to PSI; nonphotochemical quenching; yield.

MeSH terms

Droughts
Electron Transport / physiology
Electrons
Light
Photosynthesis / physiology*
Photosystem I Protein Complex / metabolism
Photosystem II Protein Complex / metabolism*
Plant Leaves / metabolism
Stress, Physiological / physiology
Water / metabolism
Zea mays / metabolism*

Substances

Photosystem I Protein Complex
Photosystem II Protein Complex
Water