Comprehensive transcriptional and functional analyses of HbGASA
genes reveal their roles in fungal pathogen resistance
in Hevea brasiliensis
Received: 7 November 2017 / Revised: 15 May 2018 / Accepted: 17 May 2018 / Published online: 26 May 2018
Springer-Verlag GmbH Germany, part of Springer Nature 2018
The gibberellic acid-stimulated arabidopsis (GASA) peptide family widely existed in plant species and plays various functions in
regulating biological processes. Based on the transcriptome and the genome of the rubber tree, 16 genes encoding the GASA
proteins were identified in Hevea brasiliensis. The phylogenetic relationship of the 16 GASA proteins of H. brasiliensis was
analyzed by comparing with that of Arabidopsis thaliana and Oryza sativa. Transcriptional assay showed that the GASA genes
were regulated by the fungal pathogens Colletotrichum gloeosporioides. Transient expression in Nicotiana benthamiana re-
vealed that the GASA genes were involved in generating reactive oxygen species, indicating their roles in plant innate immunity.
In addition, the quantitative real-time PCR assays suggested that the GASA genes were regulated by plant hormone in complex
ways. Taken together, the present study provides the comprehensive analysis and reveals putative roles of GASA genes in fungal
pathogen resistance in H. brasiliensis.
Fungal pathogen resistance
The rubber tree (Hevea brasiliensis Muell. Arg.), cultivated in
the tropics and subtropics, is the only commercial source of
polymers. The young leaves of Hevea tree are vulnerable to
pathogen attack, which influences the growth of the tree and
leads to severe loss of the rubber production. Application of
synthetic chemicals is the main method to control the rubber
tree disease at present, which causes severe environmental
pollution and is labor consuming. The introduction of plant
transgenic techniques is helpful for improving the efficiency
of breeding resistant cultivars and is environmentally friendly.
However, identification of disease-related genes in H.
brasiliensis is very limited, and the molecular mechanism of
rubber tree response to pathogens remains unclear.
The gibberellic acid-stimulated arabidopsis (GASA) pep-
tide family has been identified in a wide range of plant species
(Silverstein et al. 2007;Wangetal.2009;Ben-Nissanetal.
2004; Alonso-Ramírez et al. 2009). The name of the family
was assigned by the first identified member GAST-1
(gibberellin-stimulated transcript 1) from tomato (Shi et al.
1992). In plants, GASA proteins were speculated to be related
to various development processes, such as organ development
(Ben-Nissan et al. 2004;delaFuenteetal.2006;Kotilainenet
al. 1999), shoot and petal cell elongation (Furukawa et al.
2006), cell division, stem growth and flowering time
(Roxrud et al. 2007; Zhang et al. 2009; Zhang and Wang
2016), and seed, root, and fruit ripening (de la Fuente et al.
2006; Moyano-Cañete et al. 2013). In Arabidopsis thaliana,
14 GASA genes (GASA1–GASA14)havebeenreportedthus
far (Roxrud et al. 2007). The AtGASA5 plays important roles
in controlling flowering time and stem growth (Zhang et al.
2009), AtGASA4 was found to act as a positive regulator of
floral meristem identity and seed growth (Aubert et al. 1998;
Bang An and Qiannan Wang contributed equally to this work.
Communicated by W. Ratnam
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s11295-018-1256-y) contains supplementary
material, which is available to authorized users.
* Chaozu He
Hainan Key Laboratory for Sustainable Utilization of Tropical
Bioresources, College of Biology, Institute of Tropical Agriculture
and Forestry, Hainan University, No. 58 Renmin Road,
Haikou 570228, Hainan, China
Tree Genetics & Genomes (2018) 14: 41