Harnessing adult-plant resistance genes to deploy durable disease resistance in crops

Abstract

Adult-plant resistance (APR) is a type of genetic resistance in cereals that is effective during the later growth stages and can protect plants from a range of disease-causing pathogens. Our understanding of the functions of APR-associated genes stems from the well-studied wheat-rust pathosystem. Genes conferring APR can offer pathogen-specific resistance or multi-pathogen resistance, whereby resistance is activated following a molecular recognition event. The breeding community prefers APR to other types of resistance because it offers broad-spectrum protection that has proven to be more durable. In practice, however, deployment of new cultivars incorporating APR is challenging because there is a lack of well-characterised APRs in elite germplasm and multiple loci must be combined to achieve high levels of resistance. Genebanks provide an excellent source of genetic diversity that can be used to diversify resistance factors, but introgression of novel alleles into elite germplasm is a lengthy and challenging process. To overcome this bottleneck, new tools in breeding for resistance must be integrated to fast-track the discovery, introgression and pyramiding of APR genes. This review highlights recent advances in understanding the functions of APR genes in the well-studied wheat-rust pathosystem, the opportunities to adopt APR genes in other crops and the technology that can speed up the utilisation of new sources of APR in genebank accessions.

Harnessing genetic resistance to rusts in wheat and integrated rust management methods to develop more durable resistant cultivars

“…Following that, it was discovered that introducing wheat Lr67 into barley disrupted the functioning of HvSTP13, since the resulting transgenic lines were resistant to barley leaf rust and powdery mildew diseases. This resistant form of HvSTP13, like Lr34 in barley, is produced early in plant development in transgenic barley lines, and its protein product triggers pathogenesis-related genes to induce defense (Dinglasan et al, 2022). Nevertheless, Lr67-mediated multi-pathogen resistance is conferred by a sugar transporter protein (STP) which belongs to the sub-group STP13 (Figure 1).…”

Molecular perspectives on age‐related resistance of plants to (viral) pathogens

“…Age‐related resistance has a history of being adapted for disease management programs, where it is recognized as a key factor associated with reduced infection and yield losses in the field, such as with late blight of potatoes, stem rust of oat, multiple fungal diseases of wheat, and a variety of viral diseases (Broadfoot, 1933; Peturson, 1944; Peterson & Mills, 1953; Knutson & Bishop, 1964; Ross, 1969; Demski & Chalkley, 1974; Scott & Benedikz, 1977; Pasko et al ., 1984; Agrios et al ., 1985; Lot et al ., 1998; Dinglasan et al ., 2022; Eigenbrode & Gomulkiewicz, 2022). As an illustration, wheat breeders have been targeting ARR‐associated genes for over a century to confer stem rust resistance (Dinglasan et al ., 2022). Cultivation practices often incorporate ARR by adjusting planting to avoid exposing crops at susceptible ages to a seasonally active pathogen.…”

A single NLR gene confers resistance to leaf and stripe rust in wheat

“…Lr/Yr548 did not prevent host invasion and did not completely block the pathogen, but it slowed pathogen development and disease progression. Incomplete/quantitative resistance is often associated with plant age, namely genes that confer adult plant resistance (APR), which is manifested as partial resistance in adult plants but not in seedlings [63][64][65] . Lr/Yr548 did not confer resistance against stem rust or powdery mildew, indicating that it is not a multiple-pathogen resistance gene but is specific to leaf and stripe rusts.…”