Maize (Zea mays L.) responses to heat stress: Mechanisms that disrupt the development and hormone balance of tassels and pollen

Abstract

Global climate changes have led to frequent and recurrent heat stress, which has seriously affected the world maize production. The experiment presented in this paper was carried out during the maize‐growing season in 2021 and 2022 at the Huang–Huai–Hai Region Maize Science and Technology Innovation Center (36°09′N, 117°09′E) in Tai'an, Shandong province, China. The test site is located in the semi‐humid warm temperate continental monsoon climate zone, soil is brown loam. We selected different heat‐sensitive maize varieties: heat‐tolerant variety Zhengdan 958 (ZD958) and heat‐sensitive variety Xianyu335 (XY335) to study the stress effects of high temperature on the development of tassel in the key stage of its differentiation (the 12‐leaf stage, V12). We found that exposure to heat stress during the V12 stage significantly reduced the tassel size and the anther dehiscence area, making it difficult to disperse pollen, thus effectively reducing pollen production. In addition, heat stress had significant negative effects on pollen development, resulting in deformed pollen and lower pollen viability and germination rate. Our results also showed that heat stress significantly increased the activities of key reactive oxygen species‐scavenging enzymes including superoxide dismutase, peroxidase and catalase, and that the malondialdehyde and H2O2 content in tassels exposed to heat stress were significantly higher than those control group, where it should be noted that for the XY335, these effects were more pronounced than for the ZD958. The endogenous hormone content of tassels exhibited a variety of responses. After heat stress, the zeatin and salicylic acid content in tassels of both maize varieties were significantly lower than those in the respective control groups, while the abscisic acid and gibberellin acid content were significantly higher. With respect to the jasmonic acid and 3‐indoleacetic acid content, the two maize varieties exhibited opposite responses: in tassels from ZD958 plants subjected to heat stress were higher than those in the respective control group, while in tassels from XY335 plants, they were lower. The observed changes in protective enzyme activities and endogenous hormone contents induced by heat stress significantly affected the development of maize tassels and significantly reduced the amount, activity and germination rate of pollen.

Exogenous abscisic acid (ABA) improves the filling process of maize grains at different ear positions by promoting starch accumulation and regulating hormone levels under high planting density

“…ZR, IAA, ABA, and GA 3 levels were determined by high-performance liquid chromatography as recommended by [ 59 ]. Each hormone was measured against standards supplied by Suzhou Comin Biotechnology Co., Ltd., Suzhou, China.…”

Water productivity at two sowing dates of simple white grain maize hybrids

“…In addition, the effect of temperature can affect the hormone imbalance in maize. In a study developed to evaluate the zeatin and salicylic acid content in the ears of two experimental maize varieties, it was reduced by more than 15% with respect to the control due to the effect of temperature associated with the crop cycle; whereas, the content of abscisic and gibberellic acids increased, affecting the normal plant metabolism and grain yield (Sun et al, 2023).…”

Effects of 6-Benzyladenine (6-BA) on the Filling Process of Maize Grains Placed at Different Ear Positions under High Planting Density

“…ZR, IAA, ABA, and GA 3 were extracted with 80% (v/v) methanol and then analyzed by high-performance liquid chromatography (LC-10 AD, Shimadzu, Japan), as described by Sun et al [78]. Standards for each hormone were purchased from Beijing Solarbio Science & Technology Co., Ltd., Beijing, China.…”