BvcZR3 and BvHs1pro-1 Genes Pyramiding Enhanced Beet Cyst Nematode (Heterodera schachtii Schm.) Resistance in Oilseed Rape (Brassica napus L.)

Abstract

Beet cyst nematode (Heterodera schachtii Schm.) is one of the most damaging pests in sugar beet growing areas around the world. The Hs1pro-1 and cZR3 genes confer resistance to the beet cyst nematode, and both were cloned from sugar beet translocation line (A906001). The translocation line carried the locus from B. procumbens chromosome 1 including Hs1pro-1 gene and resistance gene analogs (RGA), which confer resistance to Heterodera schachtii. In this research, BvHs1pro-1 and BvcZR3 genes were transferred into oilseed rape to obtain different transgenic lines by A. tumefaciens mediated transformation method. The cZR3Hs1pro-1 gene was pyramided into the same plants by crossing homozygous cZR3 and Hs1pro-1 plants to identify the function and interaction of cZR3 and Hs1pro-1 genes. In vitro and in vivo cyst nematode resistance tests showed that cZR3 and Hs1pro-1 plants could be infested by beet cyst nematode (BCN) juveniles, however a large fraction of penetrated nematode juveniles was not able to develop normally and stagnated in roots of transgenic plants, consequently resulting in a significant reduction in the number of developed nematode females. A higher efficiency in inhibition of nematode females was observed in plants expressing pyramiding genes than in those only expressing a single gene. Molecular analysis demonstrated that BvHs1pro-1 and BvcZR3 gene expressions in oilseed rape constitutively activated transcription of plant-defense related genes such as NPR1 (non-expresser of PR1), SGT1b (enhanced disease resistance 1) and RAR1 (suppressor of the G2 allele of skp1). Transcript of NPR1 gene in transgenic cZR3 and Hs1pro-1 plants were slightly up-regulated, while its expression was considerably enhanced in cZR3Hs1pro-1 gene pyramiding plants. The expression of EDS1 gene did not change significantly among transgenic cZR3, Hs1pro-1 and cZR3Hs1pro-1 gene pyramiding plants and wild type. The expression of SGT1b gene was slightly up-regulated in transgenic cZR3 and Hs1pro-1 plants compared with the wild type, however, its expression was not changed in cZR3Hs1pro-1 gene pyramiding plant and had no interaction effect. RAR1 gene expression was significantly up-regulated in transgenic cZR3 and cZR3Hs1pro-1 genes pyramiding plants, but almost no expression was found in Hs1pro-1 transgenic plants. These results show that nematode resistance genes from sugar beet were functional in oilseed rape and conferred BCN resistance by activation of a CC-NBS-LRR R gene mediated resistance response. The gene pyramiding had enhanced resistance, thus offering a novel approach for the BCN control by preventing the propagation of BCN in oilseed rape. The transgenic oilseed rape could be used as a trap crop to offer an alternative method for beet cyst nematode control.

Understanding Host–Pathogen Interactions in Brassica napus in the Omics Era

“…Global transcription sequencing also revealed that JA and ET signalling were associated with a resistance response against S. sclerotiorum in B. napus [ 137 , 138 ]; a further transcriptome study in the same pathosystem demonstrated the downregulation of B. napus NPR1-like gene, BnaNPR1 , which plays a role in SA and JA signalling, indicating that S. sclerotiorum suppresses the expression of BnaNPR1 during systemic acquired resistance (SAR) for successful invasion into the host cell [ 139 ]. It is also noteworthy that NPR1 genes were activated by NBS-LRR genes, as reported in a gene pyramiding study in B. napus using two NBS-LRR genes, BvHs1 pro−1 and BvcZR3 , obtained from nematode ( Heterodera schachtii )-resistant sugar beet [ 140 ]. The gene interaction network of NPR1 and NBS-LRR should be studied further in relation to other defence-related genes.…”

Molecular Breeding Strategy and Challenges Towards Improvement of Downy Mildew Resistance in Cauliflower (Brassica oleracea var. botrytis L.)

“…Though, the multi-loci gene pyramiding has been fully utilized in several crops, the technique has not been fully utilized in B. oleracea for biotic stress resistance. But in B. rapa and B. napus , several authors have attempted to pyramid multiple resistance loci for clubroot ( Matsumoto et al, 2012 ; Shah et al, 2019 ) and nematode resistance ( Zhong et al, 2019 ) by polymerization of several identified resistance loci/genes by marker-assisted selection. Shah et al (2019) pyramided two clubroot resistance genes ( CRb and PbBa8.1 ) through marker-assisted selection and developed homozygous lines which showed strong resistance against a number of P. brassicae field isolates compared with the heterozygous pyramided and single resistant homozygous lines of B. napus .…”

The Brassica napus L. plants expressing antimicrobial peptide cecropin P1 are safe for colonization by beneficial associative microorganisms

“…Oilseed rape (Brassica napus L.) is an important oilseed and fodder crop (Peng et al 2018;Hegelian et al 2018), producing valuable biotechnological products (Ravanfar et al 2017). Many transgenic herbicide-resistant Brassica napus plants (Nishizawa et al 2016;Zhang et al 2018), and plants resistant to insects (Wang et al 2005), nematodes (Zhong et al 2019), and certain diseases (Larkan et al 2013;Ziaei et al 2016;Aghazadeh et al 2016) are also known.…”