Caspase 3‐like protease is involved in ethylene‐induced programmed cell death during aerenchyma formation in Helianthus annuus stem

Abstract

Previous research has reported that hypoxic conditions and ethylene treatments greatly trigger programmed cell death (PCD) occurrence and induce the formation of aerenchyma to adapt stress environment in Helianthus annuus stem. Caspase 3‐like protease (CLP) as regulatory signals, also be involved in the process of PCD to adapt the low oxygen environment. However, the relationships between ethylene and CLP have seldom been reported. Herein, To understand the regulatory role of ethylene and CLP signaling molecules in aerenchyma formation, we investigated the effects of exogenous ethephon (ET), ethylene perception inhibitor 1‐methylcyclopropene (1‐MCP), and the treatment of 1‐MCP + ET on morphological, physiological characteristics and aerenchyma formation in H. annuus stem. The results showed that lysigenous aerenchyma formation in H. annuus stem is induced by ET, and immunohistochemistry assay indicate CLP activity is raised at the formation stage of aerenchyma formation, and decreased at the expanding phase of aerenchyma formation. Western blotting illustrate the expression of CLP is also increased within 8 h after ethylene signaling inducing aerenchyma formation, and the activities of CLP are higher in ET treated seedlings than the control and 1‐MCP treated seedlings. The same phenomenon was also observed by caspase‐3 activity assay. These results revealed there is a causal and interdependent relationship between ET and CLP signaling during the process of aerenchyma formation, which regulating PCD initiation in H. annuus stem.

Cloning and expression analysis of Aerenchyma development related ShRBOH1 gene in Saussurea inversa Raab-Straube

“…Because of the high altitude and geographic location, plants growing above the Tibetan Plateau are subjected to low temperatures, low oxygen, and intense ultraviolet (UV) stress all year round, making them ecologically fragile. Anatomical studies on these alpine plants found that they have well-developed aerenchyma (Dawa et al, 2009), so aerenchyma may be an adaptive structure of alpine plants to alpine low temperature, low oxygen and intense UV stress, and studies have shown that respiratory burst oxidase homologue (RBOH) has a significant role in aerenchyma formation (Liu et al 2019;Ni et al, 2022).…”

“…In situ, root, stem, and leaf tissues of S. inversa plants were collected for the study of tissue expression patterns of genes. The S. inversa during the nutritive growth period was selected as the experimental subject, and the method of Ni (Ni et al, 2022) was referred to to simulate the extreme environment of alpine, and the plants with 5-6 true leaves and the same growth were selected, and the controlled variable method was adopted to subject them to the UV, cold and hypoxia stresses, respectively. A control group was set up with the same growth conditions except for no stress, and a group of plants was taken out at set time intervals, and 0.1g of tissue samples were weighed and preserved in liquid nitrogen so that fluorescence quantitative PCR was used to detect the response of ShRBOH1 to the three kinds of stress treatments, which were: UV stress.…”