Reduced seed germination in Arabidopsis over‐expressing SWI/SNF2 ATPase genes

Abstract

In the life of flowering plants, seed germination is a critical step to ensure survival into the next generation. Generally the seed prior to germination has been in a dormant state with a low rate of metabolism. In the transition from a dormant seed to a germinating seed, various epigenetic mechanisms play a regulatory role. Here, we demonstrate that the over-expression of chromatin remodeling ATPase genes (AtCHR12 or AtCHR23) reduced the frequency of seed germination in Arabidopsis thaliana up to 30% relative to the wild-type seeds. On the other hand, single loss-of-function mutations of the two genes did not affect seed germination. The reduction of germination in over-expressing mutants was more pronounced in stress conditions (salt or high temperature), showing the impact of the environment. Reduced germinations upon over-expression coincided with increased transcript levels of seed maturation genes and with reduced degradation of their mRNAs stored in dry seeds. Our results indicate that repression of AtCHR12/23 gene expression in germinating wild-type Arabidopsis seeds is required for full germination. This establishes a functional link between chromatin modifiers and regulatory networks towards seed maturation and germination.

Roles and activities of chromatin remodeling ATPases in plants

“…On the basis of overexpression studies, it was suggested that MINU1 promotes growth arrest upon drought or heat stress in adult Arabidopsis plants (Mlynarova et al ., ). Overexpression of either MINU1 or MINU2 also reduces the rate of seed germination; the defect is more pronounced in conditions of salt, heat and ABA stress (Leeggangers et al ., ). The authors observed elevated expression of seed maturation genes ( AtS2 , At2S3 ) in MINU overexpressing plants, several of these are upregulated in brm mutants and direct BRM targets (Tang et al ., ).…”

“…MINU2 overexpression also caused reduced growth (Folta et al ., ). Intriguingly, expression of endogenous MINU1 and MINU2 in the wild type decreases during germination (Leeggangers et al ., ).…”

“…In Arabidopsis, SWI/SNF and CHD3 and associated complex components are broadly expressed in all rapidly dividing cells (Ogas et al ., ; Wagner and Meyerowitz, ; Wu et al ., ), although notable exceptions exist (Jing et al ., ; Leeggangers et al ., ). How then can selective activity of SWI/SNF and CHD3 chromatin remodeling ATPases be achieved?…”

An Updated Overview on the Regulation of Seed Germination

“…PKL is required for about 80% of the gene expression changes triggered by GAs [184]. On the other hand, the repression of the CHR12/23 genes (SWI2/SNF2 subgroup ATPases) is required for full germination since their overexpression represses germination by elevating the levels of maturation-related genes [185].…”

Identifying novel fruit-related genes in Arabidopsis thaliana based on the random walk with restart algorithm

“…Not all mature seeds of a plant can grow into fertile plants. During the germination and growing processes of a mature seed, the surrounding environment is highly significant [ 4 , 5 ]. During transfer of the seed to a proper environment for further germination and growth, fruits play a crucial role [ 5 ].…”