Genome-wide analysis of autophagy-related genes in banana highlights MaATG8s in cell death and autophagy in immune response to Fusarium wilt

Abstract

MaATG8s play important roles in hypersensitive-like cell death and immune response, and autophagy is essential for disease resistance against Foc in banana. Autophagy is responsible for the degradation of damaged cytoplasmic constituents in the lysosomes or vacuoles. Although the effects of autophagy have been extensively revealed in model plants, the possible roles of autophagy-related gene in banana remain unknown. In this study, 32 MaATGs were identified in the draft genome, and the profiles of several MaATGs in response to fungal pathogen Fusarium oxysporum f. sp. cubense (Foc) were also revealled. We found that seven MaATG8s were commonly regulated by Foc. Through transient expression in Nicotiana benthamiana leaves, we highlight the novel roles of MaATG8s in conferring hypersensitive-like cell death, and MaATG8s-mediated hypersensitive response-like cell death is dependent on autophagy. Notablly, autophagy inhibitor 3-methyladenine (3-MA) treatment resulted in decreased disease resistance in response to Foc4, and the effect of 3-MA treatment could be rescued by exogenous salicylic acid, jasmonic acid and ethylene, indicating the involvement of autophagy-mediated plant hormones in banana resistance to Fusarium wilt. Taken together, this study may extend our understanding the putative role of MaATG8s in hypersensitive-like cell death and the essential role of autophagy in immune response against Foc in banana.

Comprehensive Analysis of Autophagy-Related Genes in Sweet Orange (Citrus sinensis) Highlights Their Roles in Response to Abiotic Stresses

“…Similarly, a total of 19 core CsATGs, including 35 members, were identified from the sweet orange genome in this study. The quantity of ATGs in sweet orange is similar to the quantity in grape (35 VvATGs) [13], banana (32 MaATGs) [12], rice (33 OsATGs) [7], and foxtail millet (37 SiATGs) [11], suggesting very conservative evolution of ATGs in these plants. Among the 19 core CsATGs, we found that CsATG1, CsATG8, and CsATG18 contained multiple members, which is similar to that in Arabidopsis and other plants [1,8,13].…”

“…Most ATGs were first identified and functionally characterized by mutagenesis studies in yeast [2]. More than 30 ATGs have now been identified in yeast, and 23, including ATG1-10, [12][13][14][16][17][18]20,27,29,31,TOR,VPS15,and VPS34, are considered to be the core ATGs participating in autophagy [3,4]. In Arabidopsis, around 40 homologues to these core ATGs have been identified, except for ATG14, 17,27,29, and 31 with no homologues [1,3].…”

“…The first ATG gene was identified from yeast, and at least 32 ATGs have been shown to participate in yeast autophagy [5,6]. To date, many homologues of ATGs have been identified from various plant species, including 40 AtATGs in Arabidopsis [1,3] (Arabidopsis thaliana, At), 33 OsATGs in rice [7] (Oryza sativa, Os), 30 NtATGs in tobacco [8] (Nicotiana tabacum, Nt), 45 ZmATGs in maize [9] (Zea mays, Zm), 29 CaATGs in pepper [10] (Capsicum annuum, Ca), 37 SiATGs in foxtail millet [11] (Setaria italic, Si), 32 MaATGs in banana [12] (Musa acuminate, Ma), and 35 VvATGs in grapevine [13] (Vitis vinifera, Vv). According to the reported characterizations of ATGs in yeast and Arabidopsis, these ATGs can be divided into the following functional groups: (1) the ATG1/13 kinase complex consisting of ATG1, ATG13, ATG20, and TOR (target of rapamycin kinase), mainly functioning on autophagy induction and initiation; (2) the PI3K (phosphatidylinositol 3 kinase) complex consisting of ATG6, VPS15 (vacuolar protein sorting-associated protein), and VPS34 that is involved in vesicle nucleation and autophagosome formation; (3) the ATG9/2/18 complex consisting of ATG9, ATG2, and ATG18 that is responsible for the delivery of membranes for autophagosome formation; (4) the ubiquitin-like ATG8-PE (phosphatidylethanolamine) conjugation pathway (including ATG3, ATG4, ATG7, and ATG8) and ATG12-ATG5 conjugation pathway (including ATG5, ATG7, ATG10, ATG12, and ATG16) that are involved in the elongation of autophagic vesicles; and (5) the VTI12 (vesicle transport v-soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (SNARE) protein) family belonging to the SNARE group, which contributes to the fusion of autophagosomes with vacuoles [1][2][3][4]6].…”

“…The autophagy process maintains a basal level under normal conditions, but it can be quickly induced by external stimuli such as nutrition starvation, drought, salt, heat, and oxidative and osmotic stresses [3,12,[14][15][16]. Many studies have demonstrated the functions of ATGs in alleviating abiotic stresses in plants.…”

Heat shock transcription factor 3 regulates plant immune response through modulation of salicylic acid accumulation and signalling in cassava

“…The endogenous SA level in plant leaves was extracted and examined as described previously by Shi et al (2014) and Wei et al (2017b).…”