Field resistance to wheat stem rust in durum wheat accessions deposited at the USDA National Small Grains Collection

Abstract

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is a re-emerging disease, posing a significant threat to durum wheat production worldwide. The limited number of stem rust resistance genes in modern cultivars compels us to identify and incorporate new effective genes in durum wheat breeding programs. We evaluated 8,245 spring durum wheat accessions deposited at the USDA National Small Grains Collection (NSGC) for resistance in field stem rust nurseries in Debre Zeit, Ethiopia and St. Paul, MN (USA). A higher level of disease development was observed at the Debre Zeit nursery compared with St. Paul, and the effective alleles of Sr13 in this nursery did not display the level of resistance observed at the St. Paul nursery. Four hundred and ninety-one (∽6%) accessions exhibited resistant to moderately susceptible responses after three field evaluations at Debre Zeit and two at St. Paul. Nearly 70% of these accessions originated from Ethiopia, Mexico, Egypt, and USA. Eight additional countries, namely Portugal,

Mining Sources of Resistance to Durum Leaf Rust among Tetraploid Wheat Accessions from CIMMYT’s Germplasm Bank

“…Recent studies have clearly demonstrated the potential of landraces to contribute diverse alleles for economic traits [ 32 , 33 , 34 , 35 , 36 , 37 ]. There are several examples of mining sources of resistance among the durum and tetraploid accessions in collections available in germplasm banks [ 6 , 33 , 34 , 35 , 36 , 38 , 39 , 40 , 41 , 42 , 43 ]. Mining these sources of resistance at times are very specific: for leaf rust as an example [ 6 , 38 , 41 ], yellow rust [ 39 , 40 , 43 ], stem rust [ 40 , 41 ], or other diseases [ 37 ].…”

“…There are several examples of mining sources of resistance among the durum and tetraploid accessions in collections available in germplasm banks [ 6 , 33 , 34 , 35 , 36 , 38 , 39 , 40 , 41 , 42 , 43 ]. Mining these sources of resistance at times are very specific: for leaf rust as an example [ 6 , 38 , 41 ], yellow rust [ 39 , 40 , 43 ], stem rust [ 40 , 41 ], or other diseases [ 37 ]. However, in only a few cases was resistance screening undertaken with the appropriate leaf rust races [ 25 , 38 , 44 ].…”

Genome‐wide association mapping of seedling and adult plant response to stem rust in a durum wheat panel

“…The higher proportion of susceptible lines against race JRCQC compared with race TKTTF (TKTTF_MS18) agrees with the findings of Hundie et al (2019) on evaluation of 14 durum wheat cultivars against four single races. Sr13a is moderately effective against JRCQC; however, the high frequency of susceptible lines to this race could also be explained by the reduced effect of this gene under field conditions (Olivera, et al, 2021), or the temperature dependence of Sr13 effectiveness as reported by Zhang et al (2017) in greenhouse evaluation of wheat lines, which may apply in the field because of the expected seasonal variation in temperature. The low frequency of resistant lines in TKTTF_MS19 was unusual, as durum wheat is known to have better resistance against race TKTTF.…”

Status of Ethiopian durum wheat varieties for the stem rust disease resistance under field condition

“…Recently, durum wheat accessions collections from around the world were tested for stem rust at hot spot locations, including here in Debre-zeit, Ethiopia, and Minnesota, USA. Surprisingly, the results showed that 98% of Ethiopian landraces were found to be resistant (Olivera et al, 2021). As a result, taking advantage of our natural resources is significantly better for the national breeding program for stem rust resistance.…”