Tomato SlPUB24 enhances resistance to Xanthomonas euvesicatoria pv. perforans race T3

Xin Liu,Ge Meng,Mengrui Wang,Zilin Qian,Wencai Yang,Yaxian Zhang

doi:10.1038/s41438-021-00468-4

Abstract

Solanum lycopersicum var. cerasiforme accession PI 114490 has broad-spectrum resistance to bacterial spot caused by several species of Xanthomonas. Resistance is quantitatively inherited, and a common quantitative trait locus QTL-11B on chromosome 11 has been identified previously. In this study, the SlPub24 gene was characterized in QTL-11B. SlPub24 in PI 114490 was upregulated by infection with X. euvesicatoria pv. perforans race T3, but its transcription was low in the susceptible line OH 88119 whether or not it was infected by the pathogen. The differential expression of SlPub24 between PI 114490 and OH 88119 was due to great sequence variation in the promoter region. The promoter of SlPub24 in OH 88119 had very low activity and did not respond to pathogen infection. Transgenic lines of OH 88119 overexpressing SlPub24 isolated from PI 114490 showed significantly enhanced resistance, while mutants of Slpub24 generated by CRISPR/Cas9 editing showed more susceptibility to race T3 and to other races. The mutants also showed spontaneous cell death in leaves. The expression of the salicylic acid (SA) pathway gene phenylalanine ammonia-lyase (PAL) and signaling-related genes pathogenesis-related (PR1) and nonexpresser of PR1 (NPR1) were influenced by SlPub24. The content of SA in tomato plants was consistent with the level of SlPub24 expression. Furthermore, SlPUB24 interacted with the cell wall protein SlCWP and could regulate the degradation of SlCWP. The expression levels of SlCWP and SlCWINV1, a cell wall invertase gene, showed opposite patterns during pathogen infection. The activity of SlCWINV1 was lower in mutants than in PI 114490. The results are discussed in terms of the roles of the abovementioned genes, and a potential model for SlPUB24-mediated resistance to bacterial spot is proposed.

Highlights

Introduction Bacterial spot caused byXanthomonas euvesicatoria pv.euvesicatoria, X. vesicatoria, X. euvesicatoria pv. perforans, and X. cynarae pv. gardneri is a widespread disease in tomato production[1,2,3]
Full-length cDNA was obtained by RT-PCR and RACE
Alignment of genomic DNA and cDNA sequences revealed that there was no intron in the gene

Summary

Introduction

Introduction Bacterial spot caused byXanthomonas euvesicatoria pv.euvesicatoria (race T1), X. vesicatoria (race T2), X. euvesicatoria pv. perforans (races T3 and T4), and X. cynarae pv. gardneri is a widespread disease in tomato production[1,2,3]. Gardneri is a widespread disease in tomato production[1,2,3]. The disease can cause severe yield loss and fruit quality reduction in tomato[4,5]. The use of resistant varieties is the most effective approach for control of the disease, the existence of multiple species of Xanthomonas and quick shifts of species/races in the same region are among the most important causes of unsuccessful management of the disease[4,5,6]. Cerasiforme accession PI 114490 may provide broad-spectrum resistance to all species and races of Xanthomonas causing bacterial spot in tomato[7,8,9]. The resistance to races T1–T4 and X. cynarae pv. Classical genetic analyses based on segregation of resistance in F2 and inbred backcross (IBC) populations derived from PI

Methods

Results

Conclusion