Understanding and comprehensive evaluation of cold resistance in the seedlings of multiple maize genotypes

Authors: ZHAO, XIAOQIANG - Gansu Agricultural Uiversity; ZHAO, CAI - Gansu Agricultural Uiversity; NEU, YINING - Gansu Agricultural Uiversity; Chao, Wun; HE, WEI - Gansu Agricultural Uiversity; WANG, YIFAN - Gansu Agricultural Uiversity; MAO, TAOTAO - Gansu Agricultural Uiversity; BAI, XIAODONG - Gansu Agricultural Uiversity

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2022
Publication Date: 7/20/2022
Citation: Zhao, X., Zhao, C., Neu, Y., Chao, W.S., He, W., Wang, Y., Mao, T., Bai, X. 2022. Understanding and comprehensive evaluation of cold resistance in the seedlings of multiple maize genotypes. Plants. 11(4). Article 1881. https://doi.org/10.3390/plants11141881.
DOI: https://doi.org/10.3390/plants11141881

Interpretive Summary: Maize is highly sensitive to cold stress, particularly at seedling emergence stage. Cold damage generally occurs when seedlings are exposed to cold snaps in early spring. In this study, we compared changes of 29 observable and measurable traits (phenotypic traits) in the seedlings of 39 different maize lines after subjecting these seedlings under 10°C (low temperature) or 22°C (normal temperature) for 7 days. Our results showed that low temperature can enhance the cold resistance of maize seedlings by maintaining high levels of several phenotypic traits such as membrane stability, chlorophyll content, photosynthetic capacity, and so forth. Importantly, 16 phenotypic traits can be good indicators for screening of cold–resistant maize lines. We also identified seven strong cold–resistant lines based on analyses of those phenotypic traits, and these lines can be used as parents in maize breeding programs to develop new cold–resistant varieties.

Technical Abstract: Maize is a cold sensitive crop, and it exhibits severe retardation of growth and development when exposed to cold snaps during and right after seedling emergence. Although different agronomic, physiological, and molecular approaches have been tried to overcome the problems related to cold stress in recent years, the mechanisms causing cold resistance in maize is still unclear. Screening and breeding of varieties for cold resistance may be a sustainable option to boost maize production under low temperature environments. Herein, seedlings of 39 different maize genotypes were treated under both 10°C low temperature and 22°C normal temperature conditions for 7 days to assess the changes in seven growth parameters, two membrane characteristics, two reactive oxygen species (ROS) levels and four antioxidant enzymes activities. The changes of ten photosynthetic performances, one osmotic substance accumulation, and three polyamines (PAs) metabolisms were also measured. Results indicated that significant differences among genotypes, temperature treatments, and their interactions were found in 29 studied traits, and cold–stressed seedlings were capable to enhance their cold resistance by maintaining high levels of membrane stability, antioxidant enzymes activities, chlorophyll content, photosynthetic capacity, and PAs accumulation, particularly under extended cold stress. Importantly, 16 traits can be good indicators for screening of cold–resistant genotypes of maize. Gene expression analysis showed that GRMZM2G059991, GRMZM2G089982, GRMZM2G088212, GRMZM2G396553, GRMZM2G120578, and GRMZM2G396856 were involved in antioxidant enzymes activity and PAs metabolism, which may be used as candidate genes for genetic modification to improve maize cold resistance. Moreover, seven strong cold–resistant genotypes were identified, and they can be used as parents in maize breeding programs to develop new varieties.