Genetic gains in grain yield, net photosynthesis and stomatal conductance achieved in Henan Province of China between 1981 and 2008

Genetic Gains in Grain Yield and Physiological Traits of Winter Wheat in Shandong Province, China, from 1969 to 2006

Genotype specificity is a big problem lagging the development of efficient hexaploid wheat transformation system. Increasingly, the biosecurity of genetically modified organisms is garnering public attention, so the generation of marker-free transgenic plants is very important to the eventual potential commercial release of transgenic wheat. In this study, 15 commercial Chinese hexaploid wheat varieties were successfully transformed via an Agrobacterium-mediated method, with efficiency of up to 37.7%, as confirmed by the use of Quickstix strips, histochemical staining, PCR analysis and Southern blotting. Of particular interest, marker-free transgenic wheat plants from various commercial Chinese varieties and their F1 hybrids were successfully obtained for the first time, with a frequency of 4.3%, using a plasmid harbouring two independent T-DNA regions. The average co-integration frequency of the gus and the bar genes located on the two independent T-DNA regions was 49.0% in T0 plants. We further found that the efficiency of generating marker-free plants was related to the number of bar gene copies integrated in the genome. Marker-free transgenic wheat plants were identified in the progeny of three transgenic lines that had only one or two bar gene copies. Moreover, silencing of the bar gene was detected in 30.7% of T1 positive plants, but the gus gene was never found to be silenced in T1 plants. Bisulphite genomic sequencing suggested that DNA methylation in the 35S promoter of the bar gene regulatory region might be the main reason for bar gene silencing in the transgenic plants.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/pbi.12660

Generation of marker-free transgenic hexaploid wheat via an Agrobacterium-mediated co-transformation strategy in commercial Chinese wheat varieties.

Leaf rust and powdery mildew, caused by Puccinia triticina and Blumeria graminis f. sp. tritici, respectively, are widespread fungal diseases of wheat (Triticum aestivum L.). Development of cultivars with durable resistance is crucially important for global wheat production. This paper reviews the progress of genetic study and application of adult plant resistance (APR) to wheat leaf rust and powdery mildew. Eighty leaf rust and 119 powdery mildew APR quantitative trait loci (QTL) have been reported on 16 and 21 chromosomes, respectively, in over 50 publications during the last 15 yr. More important, we found 11 loci located on chromosomes 1BS, 1BL, 2AL, 2BS (2), 2DL, 4DL, 5BL, 6AL, 7BL, and 7DS showing pleiotropic effects on resistance to leaf rust, stripe rust, and powdery mildew. Among these, QTL on chromosomes 1BL, 4DL, and 7DS also correlate with leaf tip necrosis. Fine mapping and cloning of these QTL will be achieved with the advent of cheaper high-throughput genotyping technologies. Germplasm carrying these potential resistance genes will be useful for developing cultivars with durable multidisease resistance. In addition to its non-NBS–LRR (nucleotide binding site–leucine rich repeat) structure, the senescence-like processes induced by Lr34 could be the reason for durability of resistance; however, more information is needed for a full understanding of the molecular mechanism related to durability. Adult plant resistance genes have been used by CIMMYT for more than 30 yr and have also been transferred to many Chinese wheat varieties through shuttle breeding.

Overview and Application of QTL for Adult Plant Resistance to Leaf Rust and Powdery Mildew in Wheat

Understanding the key characteristics associated with genetic gains achieved through breeding is essential for improving yield-limiting factors and designing future breeding strategies in bread wheat (Triticum aestivum L.) cultivars. The objective of the present study was to investigate the genetic progress in yield-related and physiological traits in cultivars released from 1950 to 2012 for irrigated conditions in the southern Yellow and Huai Valleys Winter Wheat Zone. Field trials including 26 leading cultivars from 1950 to the present time were conducted at Zhengzhou and Zhoukou in Henan Province, during the 2013–2014 and 2014–2015 cropping seasons, providing data from four environments. Grain yield (GY) was significantly increased by the linear rate of 57.5 kg ha−1 yr−1 or 0.70% (R2 = 0.66, P < 0.01) and significantly correlated with increased thousandkernel weight (TKW) (r = 0.48, P < 0.05), spike number m−2 (r = 0.44, P < 0.05), kernels m−2 (r = 0.56, P < 0.01), aboveground biomass (AGBM) (r = 0.80, P < 0.01), harvest index (HI) (r = 0.84, P < 0.01), watersoluble carbohydrate at 10 d postanthesis (WSC-10) (r = 0.80, P < 0.01), and reduced plant height (PH) (r = −0.85, P < 0.01). There was no significant change in kernel number per spike, heading date, normalized difference in vegetation index at anthesis and at 10 d postanthesis, leaf area index at anthesis and at 10 d postanthesis, and canopy temperature depression at anthesis during the past 60 yr. Soil plant analysis development (SPAD) estimates of chlorophyll content at 10 d postanthesis (Chl-10) increased with year of release and were significantly correlated with GY (r = 0.69, P < 0.01), PH (r = −0.76, P < 0.01), AGBM (r = 0.52, P < 0.01), HI (r = 0.71, P < 0.01), and WSC-10 (r = 0.73, P < 0.01). Cultivars conferring Rht-D1b and RhtD1b + Rht8c showed increased GY, TKW, AGBM, HI, WSC-10, and Chl-10. Stem water solubility content can be used as a selection criterion for further improving yield potential. F. Gao, A. Rasheed, Y. Dong, Y. Xiao, X. Xia, and Z. He, Institute of Crop Science, National Wheat Improvement Center, Chinese Academy of Agricultural Sciences (CAAS), 12 Zhongguancun S. St., Beijing 100081, China; F. Gao, Key Laboratory of Soybean Biology, Soybean Research Institute, Ministry of Education, Northeast Agricultural Univ., Harbin, China; F. Gao, Keshan Agricultural Research Institute, Heilongjiang Academy of Agricultural Sciences, Keshan 161600, Heilongjiang, China; D. Ma, National Wheat Engineering Research Center, Henan Agricultural Univ., 2 Nongye Rd., Zhengzhou 450000, Henan Province, China; G. Yin, Zhoukou Academy of Agricultural Sciences, Zhoukou 466000, China; X. Wu, Key Lab. of Soybean Biology, China; A. Rasheed and Z. He, International Maize and Wheat Improvement Center (CIMMYT) China Office, c/o CAAS, 12 Zhongguancun S. St., Beijing 100081, China. F. Gao and D. Ma contributed equally to this work. Received 21 May 2016. Accepted 9 Dec. 2016. *Corresponding author (zhhecaas@163.com). Assigned to Associate Editor Ashish Saxena. Abbreviations: AGBM, aboveground biomass; Chl, SPAD estimates of chlorophyll content; Chl-10, SPAD estimates of chlorophyll content at 10 d postanthesis; Chl-A, SPAD estimates of chlorophyll content at anthesis; CTD, canopy temperature depression; CTD-10, canopy temperature depression at 10 d postanthesis; CTD-A, canopy temperature depression at anthesis; DPA, days postanthesis; GY, grain yield; HD, heading date; HI, harvest index; KASP, kompetitive allele specific polymerase chain reaction; KN, kernels m−2; KNS, kernel number per spike; LAI, leaf area index; LAI-10, leaf area index at 10 d postanthesis; LAI-A, leaf area index at anthesis; NDVI, normalized difference in vegetation index; NDVI-10, normalized difference in vegetation index at 10 d postanthesis; NDVI-A, normalized difference in vegetation index at anthesis; PH, plant height; SN, spike number m−2; SPAD, soil plant analysis development; TKW, thousand-kernel weight; WSC-10, stem water-soluble carbohydrate at 10 d postanthesis; YHVWWZ, the Yellow and Huai Valleys Winter Wheat Zone. Published in Crop Sci. 57:760–773 (2017). doi: 10.2135/cropsci2016.05.0362 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. Published March 3, 2017

Genetic Progress in Grain Yield and Physiological Traits in Chinese Wheat Cultivars of Southern Yellow and Huai Valley since 1950

Progress of wheat breeding in China and the future perspective

Stripe rust,caused by Puccinia striiformis f.sp.tritici,and powdery mildew,caused by Blumeria graminis f.sp.tritici,are the devastating diseases in common wheat(Triticum aestivum L.) worldwide.Use of adult-plant resistance(APR) genes is an important method for the development of durable resistant cultivars.A total of 72 quantitative trait loci(QTLs) for APR to stripe rust and 82 QTLs for APR to powdery mildew were integrated into a linkage map based on the information of DNA markers linked to individual QTL.Eight gene clusters(≥5 QTLs) conferred resistance to both stripe rust and powdery powdery,among them,Yr18/Lr34/Pm38,Yr29/Lr46/Pm39,and Yr46/Lr67 showed resistance to stripe rust,leaf rust and powdery mildew.Yr18/Lr34/Pm38 and Yr36 have been cloned.Xiannong 4 and Xiaoyan 6 were very important resistant germplasm for APR to stripe rust and powdery midew.The application of APR to wheat breeding in China was summarized.The use of APR genes will be a major method for improving stripe rust and powdery mildew resistance in wheat breeding.The strategies for APR on wheat breeding were also discussed.

Zhuang Qiao-Sheng

Papers

Progress of wheat breeding in China and the future perspective

Progress and perspective in research of adult-plant resistance to stripe rust and powdery mildew in wheat