Wall-associated kinases (WAKs) play an important role in plant defense and development. Considerable progress has been made in understanding WAK genes in Arabidopsis thaliana. However, much less is known about these genes in common wheat. Here, we isolated a novel wheat WAK gene TaWAK5 from sharp eyespot disease-resistant wheat line CI12633, based on a differentially-expressed sequence identified by microarray analysis. The transcript abundance of TaWAK5 was rapidly increased following inoculation with the pathogen Rhizoctonia cerealis. TaWAK5 in resistant wheat lines was induced to higher levels than in susceptible lines at 7 days post inoculation with R. cerealis. The expression of TaWAK5 was also induced by treatments with exogenous salicylic acid, abscisic acid, and methyl jasmonate. The deduced TaWAK5 protein contained a signal peptide, two epidermal growth factor (EGF)-like repeats, a transmembrane domain, and a serine/threonine protein kinase catalytic domain. Subcellular localization analyses in onion epidermal cells indicated that the TaWAK5 protein was localized to the plasma membrane. Virus-induced gene silencing of TaWAK5 in CI12633 plants showed that the silencing of TaWAK5 did not obviously impair wheat resistance to R. cerealis, suggesting that TaWAK5 may be not the major gene in wheat defense response to R. cerealis, or that it is functionally redundant with other genes. This study paves the way for further research into WAK functions in wheat stress physiology.

The fungus Magnaporthe oryzae is the causal agent of a wide range of cereal diseases. For long-term preservation, the fungus is grown and stored desiccated on filter papers at -20 °C. Inoculated filter papers are cut into pieces of 0.5-1.0 cm diameter prior to storage. In the present study, a fast (11 min) and simple method of preparing DNA suitable for amplifying avirulence genes of M. oryzae by polymerase chain reaction (PCR) was developed. A piece of filter paper containing the fungus was removed from a glass bottle and placed in a 0.2 mL Eppendorf tube containing 100 μL 10 × TE. The suspension was heated for 10 min at 95 °C in a PCR machine. The tube was then centrifuged for 1 min at 3000 r min^{− 1}. One μL of 10 × TE solution containing DNA was used for PCR. A total of 28 samples were PCR tested. As a positive control, fungal DNA was extracted using a conventional DNA preparation method. DNA samples obtained from both methods were stored at 4 °C. PCR was performed with DNA on the preparation day and after 4, 8, 10, and 18 days of refrigerated storage. In four samples, samples 12, 13, 14, and 28, AVR-Pi9 failed to be amplified. These four samples were tested with a different set of primers for AVR-Pi9, and for AVR-Pita1, confirming that the quality of the samples was insufficient for PCR. Overall, for nearly 90% (24/28) of the samples, the quality of the DNA prepared directly from the fungus on filter paper appeared suitable for a rapid survey of genetic identity of the rice blast fungus by PCR. This method will be useful and effective for reducing cost and time and could readily be adopted worldwide for analysis of M. oryzae and possibly other fungi.

Gossypium anomalum represents an inestimable source of genes that could potentially be transferred into the gene pool of cultivated cotton. To resolve interspecific hybrid sterility problems, we previously treated triploid hybrids derived from a cross between Gossypium hirsutum and G. anomalum with 0.15% colchicine and obtained a putative fertile hexaploid. In this study, we performed morphological, molecular and cytological analyses to assess the hybridity and doubled status of putative interspecific hybrid plants. Most of the morphological characteristics of the putative hexaploid plants were intermediate between G. hirsutum and G. anomalum. Analysis of mitotic metaphase plates revealed 78 chromosomes, confirming the doubled hybrid status of the hexaploid. Genome-wide molecular analysis with different genome-derived SSR markers revealed a high level of polymorphism (96.6%) between G. hirsutum and G. anomalum. The marker transferability rate from other species to G. anomalum was as high as 98.0%. The high percentage of polymorphic markers with additive banding profiles in the hexaploid indicates the hybridity of the hexaploid on a genome-wide level. A-genome-derived markers were more powerful for distinguishing the genomic differences between G. hirsutum and G. anomalum than D-genome-derived markers. This study demonstrates the hybridity and chromosomally doubled status of the (G. anomalum × G. hirsutum)² hexaploid using morphological, cytological and molecular marker methods. The informative SSR markers screened in the study will be useful marker resources for tracking the flow of G. anomalum genetic material among progenies that may be produced by future backcrosses to G. hirsutum.

Verticillium wilt (caused by the pathogen Verticillium dahliae) is of high concern for cotton producers and consumers. The major strategy for controlling this disease is the development of resistant cotton (Gossypium spp.) cultivars. We used interspecific chromosome segment introgression lines (CSILs) to identify quantitative trait loci (QTL) associated with resistance to Verticillium wilt in cotton grown in greenhouse and inoculated with three defoliating V. dahliae isolates. A total of 42 QTL, including 23 with resistance-increasing and 19 with resistance-decreasing, influenced host resistance against the three isolates. These QTL were identified and mapped on 18 chromosomes (chromosomes A1, A3, A4, A5, A7, A8, A9, A12, A13, D1, D2, D3, D4, D5, D7, D8, D11, and D12), with LOD values ranging from 3.00 to 9.29. Among the positive QTL with resistance-increasing effect, 21 conferred resistance to only one V. dahliae isolate, suggesting that resistance to V. dahliae conferred by most QTL is pathogen isolate-specific. The At subgenome of cotton had greater effect on resistance to Verticillium wilt than the Dt subgenome. We conclude that pyramiding different resistant QTL could be used to breed cotton cultivars with broad-spectrum resistance to Verticillium wilt.

For smooth and wide application of conservation agriculture (CA), remaining uncertainties about its impacts on crop yield need to be reduced. Based on previous field experiments in China, a meta-analysis was performed to quantify the actual impacts of CA practices (NT: no/reduced-tillage only, CTSR: conventional tillage with straw retention, NTSR: NT with straw retention) on crop yields as compared to conventional tillage without straw retention (CT). Although CA practices increased crop yield by 4.6% on average, there were large variations in their impacts. For each CA practice, CTSR and NTSR significantly increased crop yield by 4.9% and 6.3%, respectively, compared to CT. However, no significant effect was found for NT. Among ecological areas, significant positive effects of CA practices were found in areas with an annual precipitation below 600 mm. Similar effects were found in areas with annual mean air temperature above 5 °C. For cropping regions, CA increased crop yield by 6.4% and 5.5% compared to CT in Northwest and South China, respectively, whereas no significant effects were found in the North China and Northeast China regions. Among crops, the positive effects of CA practices were significantly higher in maize (7.5%) and rice (4.1%) than in wheat (2.9%). NT likely decreased wheat yield. Our results indicate that there are great differences in the impacts of CA practices on crop yield, owing to regional variation in climate and crop types. CA will most likely increase maize yield but reduce wheat yield. It is strongly recommended to apply CA with crop straw retention in maize cropping areas and seasons with a warm and dry climate pattern.

A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen (N), phosphorus (P), and potassium (K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development, increased nutrient accumulation, and increased yield. Compared with conventional soil management (CK), root length, root surface area, and root dry weight at 0-80 cm soil depth under subsoil tillage to 30 cm (T1) and subsoil tillage to 50 cm (T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the 12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.

Powdery mildew caused by Blumeria graminis f. sp. tritici is one of the major wheat diseases worldwide. The Chinese wheat landrace Pingyuan 50 has shown adult-plant resistance (APR) to powdery mildew in the field for over 60 years. To dissect the genetic basis of APR to powdery mildew in this cultivar, a mapping population of 137 double haploid (DH) lines derived from Pingyuan 50/Mingxian 169 was evaluated in replicated field trials for two years in Beijing (2009-2010 and 2010-2011) and one year in Anyang (2009-2010). A total of 540 polymorphic SSR markers were genotyped on the entire population for construction of a linkage map and QTL analysis. Three QTL were mapped on chromosomes 2BS (QPm.caas-2BS.2), 3BS (QPm.caas-3BS), and 5AL (QPm.caas-5AL) with the resistance alleles contributed by Pingyuan 50 explaining 5.3%, 10.2%, and 9.1% of the phenotypic variances, respectively, and one QTL on chromosome 3BL (QPm.caas-3BL) derived from Mingxian 169 accounting for 18.1% of the phenotypic variance. QPm.caas-3BS, QPm.caas-3BL, and QPm.caas-5AL appear to be new powdery mildew APR loci. QPm.caas-2BS.2 and QPm.caas-5AL are possibly pleiotropic or closely linked resistance loci to stripe rust resistance QTL. Pingyuan 50 could be a potential genetic resource to facilitate breeding for improved APR to both powdery mildew and stripe rust.

Plant expansins are a group of extracellular proteins thought to affect the quality of cotton fibers. Previous expression profile analysis revealed that six Expansin A genes are present in cotton, of which two (GhExp1 and GhExp2) produce transcripts that are specific to the developing cotton fiber. To identify the phenotypic function of Exp2, and to determine whether nucleotide variation among alleles of Exp2 affects fiber quality, candidate gene association mapping was conducted. Gene-specific primers were designed to amplify the Exp2 gene. By amplicon sequencing, the nucleotide diversity of Exp2 was investigated across 92 accessions (including 7 Gossypium arboreum, 74 Gossypium hirsutum, and 11 Gossypium barbadense accessions) with different fiber qualities. Twenty-six SNPs and seven InDels including 14 from the coding region of Exp2 were detected, forming twelve distinct haplotypes in the cotton collection. Among the 14 SNPs in the coding region, five were missense mutations and nine were synonymous nucleotide changes. The average SNP/InDel per nucleotide ratio was 2.61% (one SNP per 39 bp), with 1.81 and 3.87% occurring in coding and non-coding regions, respectively. Nucleotide and haplotype diversity across the entire Exp2 region was 0.00603 (π) and 0.844, respectively, and diversity in non-coding regions was higher than that in coding regions. For linkage disequilibrium (LD), the mean r² value for all polymorphism loci pairs was 0.48, and LD did not decay over 748 bp. Based on 132 simple sequence repeat (SSR) loci evenly covering 26 chromosomes, the population structure was estimated, and the accessions were divided into seven groups that agreed well with their genomic origin and evolutionary history. A general linear model was used to calculate the Exp2-wide diversity-trait associations of 5 fiber quality traits, considering population structure (Q). Four SNPs in Exp2 were associated with at least one of the fiber quality traits, but not with fiber elongation. The highest positive effect on UHML and STR was observed for haplotype Hap_6 of Exp2. There was a significant association of Exp2 with fiber quality traits. There were many haplotypes in the Exp2 region, of which the most favorable was Hap_6. The association between nucleotide diversity and these fiber traits sheds light on the gene's potential contribution to the improvement of fiber quality, and should be useful to facilitate MAS programs in cotton.

Cassava (Manihot esculenta Crantz) is an important root crop worldwide. It exhibits substantial differential genotypic responses to varying environmental conditions, a phenomenon termed genotype × environment interaction (GEI). A significant GEI presents challenges in the selection of superior genotypes. The objective of this study was to examine the effect of genotype, environment and GEI on early fresh storage root yield (FSRY) and related traits in cassava. Accordingly, 12 cassava genotypes were evaluated in a randomised complete block design at three contrasting locations (Jinja, Nakasongola and Namulonge) in Uganda. Trials were harvested nine months after planting and the data collected were analysed using the additive main effects and multiplicative interaction (AMMI) model. The AMMI analysis of variance showed significant variation among genotypes for early FSRY and all other traits assessed. Locations were significantly different for all traits except for cassava brown streak disease root necrosis. The GEI effect was non-significant for early FSRY, but significant for other traits. For early FSRY, 48.5% of the treatment sum of squares was attributable to genotypes, 27.3% to environments, and 24.1% to GEI, indicating a predominance of genotypic variation for this trait. Predominance of genotypic variation was also observed for all the other traits. A majority of the genotypes (67%) had low interaction effects with locations for early FSRY, with Akena, CT2, CT4 and NASE14 being the most stable genotypes for the trait. Significant negative correlation was observed between cassava mosaic disease severity and early FSRY and storage root number, indicating significant negative effects of cassava mosaic disease on early FSRY and stability in cassava. The information generated will inform future selection initiatives for superior early-yielding cassava genotypes combining resistance to cassava mosaic and brown streak diseases in Uganda.

To evaluate the response to lime on cultivars of ricebean (Vigna umbellata), a field experiment was conducted during the two consecutive rabi seasons of 2010-2011 and 2011-2012 in the Nagaland foothills, India. The experiment used a split-plot design with four levels of lime (control, 0.2, 0.4 and 0.6 t ha^{− 1}) in main plots and four ricebean cultivars (RBS-16, RBS-53, PRR-2, and RCRB-4) in sub-plots with three replicates. The results revealed that increasing levels of lime (in the furrow) from 0 to 0.6 t ha^{− 1} significantly increased growth, yield attributes and yield. The quality parameters of ricebean were also influenced significantly by the application of lime. Maximum gross return (INR 39,098 ha^{− 1}), net return (INR 27,281 ha^{− 1}), benefit:cost (B:C) ratio (2.29), production efficiency, and economic efficiency were also realized with the application of lime at 0.6 t ha^{− 1}. Among the ricebean cultivars, RBS-53 produced significantly higher growth, yield attributes, grain yield, straw yield, biological yield, and harvest index. Similarly, yield and protein content were higher in RBS-53. Maximum gross return, net return, B:C ratio, production efficiency, and economic efficiency were observed for RBS-53.