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The common wheat line, YW243, developed in our research group, was tested for the resistances of barley yellow dwarf virus (BYDV), powdery mildew (Pm) and stripe rust in field, and was analyzed by molecular markers for convenient trace of the resistant genes in breeding. Genomic in situ hybridization (GISH) analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) assay further demonstrated that YW243 was a homozygous multiple translocation line of Triticum aestivum, Thinopyrum intermedium and Secale cereale (T7DS·7DL-7XL & 1BL·1RS). The disease resistance test and marker analysis showed that YW243 carried seven resistance genes to the three diseases, including Bdv2 to BYDV on 7DL-7XL, Pm4 to powdery mildew on 2AL, Yr2, Yr9, Sr 31 and Lr26 and a new Yr to stripe rust on 7B, 1BL, 1RS and 2BL. Restriction fragment length polymorphism (RFLP) markers Xpsr687 and Xwg380 , sequence tagged site (STS) marker STS 1700 , simple sequence repeat (SSR) markers Xgwmc364 and Xgwm582 , SSR markers Xgwm388 and Xgwm501 can be used as diagnostic tools to track Bdv2, Pm4, Yr2, Yr9 and Yr in YW243 , respectively; and two amplified fragment length polymorphism (AFLP) markers M54E63 - 700 and M54E64 - 699 can also be used to select Yr in YW243 .

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Rice sheath blight, caused by Rhizoctonia solani, is the most serious disease in the southern rice producing regions of China. The use of resistant varieties is the most economic strategy to control the disease. In this paper, a seedling inoculation method was used to evaluate rice germplasm resources for resistance to sheath blight. A total of 363 rice varieties were evaluated with a set of R. solani isolates. The results indicated that the rice varieties generally lacked resistance to R. solani, and no highly resistant/immune (HR) variety was found. However, two varieties displayed clear resistance (R) and 37 showed moderate resistance (MR) to the fungus. Overall, hybrid rice varieties have better resistance than conventional rice varieties, and among hybrid rice varieties, those with the II-32A sterile line genetic background were the most resistant. The results also indicated significant interactions between rice varieties and pathogen isolates, suggesting that an understanding of local R. solani populations is needed when recommending varieties to local growers.

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Stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks., is a major disease that causes substantial losses to wheat production worldwide. The utilization of effective resistance genes in wheat cultivars is the preferred control of the disease. To study the inheritance of all-stage resistance in spring wheat cultivars Louise, WA008016, Express, Solano, Alturas and Zak from the Pacific Northwest (PNW) of the United States, the six cultivars were crossed with the Chinese susceptible variety Taichung 29. Single-spore isolates of CYR32 and CYR33, the predominant Chinese races of P. striiformis f. sp. tritici, were used to evaluate F1, F2 and BC1 generations for stripe rust resistance under controlled greenhouse conditions. Genetic analysis determined that Louise had one dominant resistance gene to CYR32, temporarily designated as YrLou. WA008016 had two dominant and one recessive resistance genes to CYR32, temporarily designated as YrWA1, YrWA2 and YrWA3, respectively. Express had a single recessive gene that conferred resistance to CYR32, temporarily designated as YrExp3. The two independent dominant genes in Solano conferring resistance to CYR32 were temporarily designated as YrSol1 and YrSol2. Alturas had two recessive genes for resistance to CYR32, temporarily designated as YrAlt1 and YrAlt2. Zak has one dominant gene for resistance to CYR33, temporarily designated as YrZak1. These six cultivars can be important resistance sources in Chinese wheat stripe rust resistance breeding.

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Cereal Research Communications
Authors:
H. Yu
,
Y. Yang
,
X.Y. Chen
,
G.X. Lin
,
J.Y. Sheng
,
J.Y. Nie
,
Q.J. Wang
,
E.J. Zhang
,
X.R. Yu
,
Z. Wang
, and
F. Xiong

The waxy wheat shows special starch quality due to high amylopectin content. However, little information is available concerning the development and degradation of amyloplast from waxy wheat endosperm. To address this problem, waxy wheat variety, Yangnuo 1, and a non-waxy wheat variety, Yangmai 13, were chosen to investigate the development and degradation of endosperm amyloplast during wheat caryopsis development and germination stage respectively using histochemical staining and light microscopy. Changes of morphology, the soluble sugar and total starch content were indistinguishable in the process of caryopsis development of two wheat varieties. The developing endosperm of non-waxy was stained blue-black by I2-KI while the endosperm of waxy wheat was stained reddish-brown, but the pericarp of waxy and non-waxy wheat was stained blue-black. In contrast to nonwaxy wheat, endosperm amyloplast of waxy wheat had better development status and higher proportion of small amyloplast. During seed germination many small dissolution pores appeared on the surface of endosperm amyloplast and the pores became bigger and deeper until amyloplast disintegrated. The rate of degradation of waxy wheat endosperm amyloplast was faster than non-waxy wheat. Our results may also be helpful to the use of waxy starch in food and nonfood industry.

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