Overexpression of the NDR1/HIN1-Like Gene NHL6 Modifies Seed Germination in Response to Abscisic Acid and Abiotic Stresses in Arabidopsis.

Yan Bao,Lei Yang,Renu Srivastava,Bei Li,Xiang Yu,Xiao-Shu Gao,Hong-Xia Zhang,Xian-Hao Cheng,Hong-Yan Su,Jing Pan,Hua Liu,Wei-Meng Song,Lu-Ying Zhu,Chun-Mei Jiang,Miguel A Blazquez

doi:10.1371/journal.pone.0148572

Abstract

NHL (NDR1/HIN1-like) genes play crucial roles in pathogen induced plant responses to biotic stress. Here, we report the possible function of NHL6 in plant response to abscisic acid (ABA) and abiotic stress. NHL6 was highly expressed in non-germinated seeds, and its expression was strongly induced by ABA and multiple abiotic stress signals. Loss-of-function of NHL6 decreased sensitivity to ABA in the early developmental stages including seed germination and post-germination seedling growth of the nhl6 mutants. However, overexpression of NHL6 increased sensitivity to ABA, salt and osmotic stress of the transgenic plants. Further studies indicated that the increased sensitivity in the 35S::NHL6 overexpressing plants could be a result of both ABA hypersensitivity and increased endogenous ABA accumulation under the stress conditions. It was also seen that the ABA-responsive element binding factors AREB1, AREB2 and ABF3 could regulate NHL6 expression at transcriptional level. Our results indicate that NHL6 plays an important role in the abiotic stresses-induced ABA signaling and biosynthesis, particularly during seed germination and early seedling development in Arabidopsis.

Highlights

The plant hormone abscisic acid (ABA) plays major roles in the process of seed germination and plant adaptation to abiotic stresses [1,2,3]
Since ABA plays a prominent role in abiotic stress adaptation and senescence, we assumed that NHL6 might function in plant response to ABA and abiotic stress
We observed that NHL6 was predominantly expressed in seeds and senescent leaves, and its expression was strongly induced by ABA, mannitol and drought stress (Fig 1A and 1C)

Summary

Introduction

The plant hormone abscisic acid (ABA) plays major roles in the process of seed germination and plant adaptation to abiotic stresses [1,2,3]. Expression of the ABA biosynthesis genes are induced, leading to enhanced synthesis of endogenous ABA [4]. Numerous Arabidopsis mutants that could germinate even in the presence of high concentrations of ABA have been identified. ABI1 (phosphatase ABA-INSENSITIVE 1) and ABI2 negatively regulate ABA signaling during seed dormancy and germination [5,6].

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Conclusion