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heat stem rust caused by Puccinia graminis f. sp. tritici (Pgt), is one of the most destructive diseases of wheat. Survey of stem rust was carried out during 2014 and 2015 seasons in Kafrelsheikh, Sharqia, and Nubaria governorates in Egypt. The physiologic races of stem rust were determined on seedlings of the standard wheat stem rust differentials following the international system of nomenclature. Results indicated the occurrence of twelve races, three in the Ug99 race group; TTKST, TTKTK, TTKSK from Al-Sharqia, Sakha and from Nubaria, respectively. The rest of races are not belonging to the Ug99 race group which was detected during the two seasons. In addition, situation was studied on monogenic Sr's lines against stem rust disease under field conditions. Sr2, Sr24 and Sr26 were highly effective for resistance in both seasons. While, Sr27 and Sr31 either was ineffective in some years, or did not confer adequate resistance. Four Egyptian wheat germplasm namely Giza164, Sakha93, Sakha94 and Sids1 with significantly low ACI, AUDPC, rAUDPC and RRI were identified. Also, these genotypes showed low disease severity moderately resistance (MR) infection type in both seasons. First occurrence of the Ug99 race of wheat stem rust (Pgt) to Egypt in 2014/15. The obtained results would serve as a fruitful tool in wheat breeding program directed for disease resistance.

Yellow rust and heat stress adversatively impact the growth and production of bread wheat in particular under rising adverse environmental conditions. Stability of grain yield is a pivotal purpose of plant breeders to improve wheat production and ensure global food security especially under abrupt climate change. The objective of this study was to assess the performance and stability of diverse bread wheat genotypes for yellow rust resistance, heat stress, and yield traits. The studied genotypes were evaluated in two different locations under two sowing dates (timely and late sowing) during two growing seasons. The obtained results displayed significant differences among the tested locations, sowing dates, and genotypes for most measured traits. The yellow rust measurements evaluated under the field conditions including final rust severity (FRS), the average coefficient of infection (ACI), and area under disease progress curve (AUDPC) revealed that Giza-171, Misr-1, Gemmeiza-12, Shandweel-1, Sids-13, Line-1, Line-2, and Line-55 had better resistance. Based on heat sensitivity measurements, Line-1 and Line-2 followed by Line-35, Shandweel-1 and Line-55 were classified as more tolerant to heat stress compared with the remaining genotypes. The genotypes Line-55, Gemmeiza-12, Giza-171, Line-1, Line-2, and Misr-1 were able to maintain acceptable agronomic performance under timely and late sowing dates in all evaluated environments. Different statistical procedures were employed to explore the adaptability and stability of tested genotypes i.e., joint regression, stratified ranking, Wricke's Ecovalence values, cultivar superiority, additive main effects, and multiplicative interaction (AMMI), AMMI stability value, and genotype plus genotype-by-environment interaction (GGE). The applied stability parameters were quite similar for describing the stability of the evaluated wheat genotypes. The results indicated that Gemmeiza-12, Giza-171, Sids-12, Sids-13, Misr-1 Shandweel-1, Line-1, Line-2, and Line-55 were desirable and stable. The heatmap and hierarchical clustering were exploited for dividing the evaluated bread wheat genotypes into different clusters based on yellow rust resistance measurements, heat tolerance indices, and agronomic performance. Line-1 and Line-2 had the best performance for all rust resistance, heat tolerance, and agronomic performance followed by Giza-171, Line-55, Line-35, Gemmeiza-12, Shandweel-1, Misr-1, and Sids-13. In conclusion, our findings provide evidence of utilizing promising genotypes in rust resistance, heat tolerance, and agronomic performance in breeding programs for improving wheat grain yield stability mainly under climate change.

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The annual survey of 2006/2007 wheat growing season revealed the presence of thrity two physiologic races of wheat leaf rust fungus (Puccinia triticina Eriks.). The more frequent race was PTTS (23.07%) followed by race PTTT (12.30%), race TTTS (9.23%), race TTTT (6.15%), race PTTP (4.61%) and the two races PSTN and PTKS which were represented by (3.07%) each. The rest of races were represented by (1.53%) each. However, the more effective leaf rust resistance genes were i.e. Lr2a (73.84%), Lr2b (61.53%) and Lr36 (50.76%). On the other hand , the highest virulence were observed with Lr's i.e., 10; 11, 14b, 17; 16, 21, 30; and 2c, 3, 24 which were represented by 100% susceptibility; 98.46%; 96.92% and 95.38%, respectively. Leaf rust resistance gene(s) probably present in four Egyptian commercial wheat cultivars in comparison with nineteen leaf rust near-isogenic lines against 65 isolates, the cultivars Gemmiza 10, Giza 168 and Sakha 94 probably have Lr's i.e. 9, 16, 24, 11, 17, 30 and 14b. On the other hand, the tested Egyptian wheat cultivars were postulated to the lack of Lr2a, Lr2b and Lr36 which were proved to be the more effective genes in the present study. These results will remain an integral part of resistance breeding program and studies relevant to the epidemology and evaluation of virulence to leaf rust pathogen populations.