Control of flowering time is crucial for reproductive success of cereal crops, and has a significant impact on grain yield as well as adaptation to diverse environmental conditions. Plants integrate signals from both environmental cues and endogenous regulatory pathways to fine-tune flowering time. The CCT domain originally described to a 43-amino acid sequence at the C-terminus of three Arabidopsis proteins, namely CONSTANS (CO), CO-LIKE, and TIMING OF CAB1 (TOC1). The CCT domain-containing genes (CCT genes), which encode transcription co-factors, are the major genetic determinants that modulate flowering time, and this in turn enables plants to effectively expand their territory to take advantage of favorable habitats. Moreover, certain CCT genes have pleiotropic effects on morphological traits and confer resistance/tolerance to biotic/abiotic stresses. CCT genes can be classified into three families, namely COL (CONSTANS-like), PRR (Pseudo-response regulator), and CMF (CCT motif family), based on their non-CCT domains. During domestication, natural and artificial selection resulted in reduced nucleotide diversity of CCT genes in modern cultivated cereals than their wild types. Here, we review the features and functions of CCT genes in cereal crops and propose future research to focus on CCT genes and their utilization in crop breeding.

During germination of barley (Hordeum vulgare L.) seeds, important morphological and physiological changes take place, including development of organs and tissues and activation of metabolic pathways. Germination and dormancy of seeds are regulated by abscisic acid, gibberellins, reactive oxygen species (ROS), reactive nitrogen species (RNS) and several other factors. Activities of ascorbate-glutathione cycle enzymes, responsible for scavenging ROS, strongly increase. Catalase and superoxide dismutase activities, also scavenging ROS, decrease at the onset of seed germination and then increase. With the increase in aerobic metabolism after radicle protrusion, the activities of the fermentation enzymes lactate and alcohol dehydrogenase decline rapidly. The RNS-scavenging activity of S-nitrosoglutathione reductase decreases in the course of seed germination, in concert with elevation of nitric oxide production and protein nitrosylation. This activity supports the role of RNS in regulating seed germination. Transcription of various genes at different phases of seed germination exhibits phase-specific changes. During imbibition, genes involved in cell wall metabolism are highly expressed; in the middle phase of seed germination before radicle protrusion, genes involved in amino acid synthesis, protein synthesis, and transport and nucleic acid synthesis are upregulated significantly, and after radicle protrusion, genes involved in photosynthetic metabolism are induced. In summary, signal transduction and metabolic regulation of seed germination involve diverse reactions and complex regulation at different levels of metabolic organization.

Rice culm carbohydrate transport can simultaneously affect grain filling and stem lodging resistance by regulating non-structural carbohydrate (NSC) and structural carbohydrate (SC) contents. However, the relationship between carbohydrate transposition and culm strength is not well documented. Accordingly, a high-yielding hybrid rice cultivar (Y Liangyou 2) was tested under different N fertilization regimes at two locations, Taoyuan (a special high-yield eco-site), Yunnan province and Danyang (a representative eco-site of the middle and lower Yangtze), Jiangsu province, China. Significantly higher grain yield and basal stem strength were found at Taoyuan than Danyang under all N rates throughout the two-year experiment. At heading stage, soluble sugars, starch, cellulose and lignin contents of the basal culm at Taoyuan were significantly 132.0%, 73.7%, 1.2%, and 62.7% higher than those at Danyang, respectively. At 20 days after heading, soluble sugars and starch content at Taoyuan decreased significantly compared to Danyang, but lignin content remained higher. Culm carbohydrate transport to kernels at Taoyuan was significantly greater than that at Danyang, and the proportion of soluble sugars and starch was correspondingly 62.9% lower. However, the proportion of lignin and cellulose was 22.7% higher at Taoyuan than that at Danyang. Soluble sugars and starch partitioning were significantly reduced under an increased nitrogen application rate, but SC partitioning was little affected. There were significant positive correlations between basal culm bending stress and dry weight and cellulose and lignin proportions at both locations under all N rates, suggesting that the higher SC proportion at 20 days after heading was primarily responsible for culm strength. These results suggest that high-yielding rice populations with greater culm strength require both moderate NSC transport and greater SC accumulation.

Worldwide, approximately 27 million ha of rice are grown in upland rather than paddy fields, and is subject to drought stress. To counter this stress, it is desirable to breed new rice cultivars with improved drought tolerance. For breeding purposes, especially for breeding upland rice, it is desirable to develop a simple and accurate method to evaluate rice drought tolerance. We describe a new method that can be used to evaluate efficiently the drought tolerance degree (DTD) of upland rice cultivars, and call it the DTD method. DTD is defined as the mean of the ratios of green leaf length to total leaf length of the top three leaves in every rice seedling after drought treatment, and thus takes values from zero to one. To test whether the DTD method works effectively to evaluate drought tolerance of upland rice cultivars, we determined the DTD values of 13 upland rice cultivars showing varying degrees of drought tolerance in drought-tolerance trials. The idr1-1 mutant, which displayed the strongest drought tolerance of the 13 cultivars as identified by drought-tolerance trials under severe drought stress, had the highest DTD value and 297-28, displaying the weakest drought tolerance, had the lowest DTD value. Further analyses of water potential, survival rate, panicles per plant, spikelets per panicle, seed setting rate, yield per plant, and contents of proline, chlorophyll, and malondialdehyde (MDA) indicated that DTD values are in general correlated with the values of these traits, making this new method useful for assessing the drought tolerance of upland rice cultivars. These results show that the DTD method is a simple, direct and relatively accurate evaluation method for drought-tolerance breeding of upland rice.

Sixty-six accessions belonging to Avena species (A. atlantica, A. canariensis, A. clauda, A. damascena, A. hirtula, A. longiglumis, A. wiestii, A. agadiriana, A. barbata, A. vaviloviana, A. insularis, A. magna, A. murphyi, A. fatua, A. ludoviciana, A. occidentalis, A. sterilis, A. sativa, and A. byzantina) obtained from the N. I. Vavilov Institute of Plant Genetic Resources (VIR) were tested for the infection of grain by Alternaria and Cladosporium at the genus level and by a group of trichothecene-producing Fusarium fungi. Real-time PCR was performed to quantify fungal abundance and ELISA was performed for mycotoxin analysis in grain. The average amounts of all tested fungi in tetraploid Avena species were higher than those in diploid and hexaploid species. Low amounts of deoxynivalenol (DON) were detected in seven hexaploid genotypes (A. sterilis, A. byzantina, A. sativa, and A. fatua) and one diploid genotype (A. wiestii). The relationship between some morphological traits (1000-grain weight, percent of husk, trichome density, and plant height) of Avena species and grain infection by fungi and mycotoxins was investigated. Alternaria and Cladosporium fungi could not penetrate the husk. A highly negative correlation of the amounts of their DNA with the proportions of husk in grain as well as with trichome density was found. In contrast, a significant positive correlation between the amount of Fusarium DNA and these traits was found. A strong negative correlation between plant height and DNA of the analyzed fungi was found. The oats least infected by Alternaria, Cladosporium, and Fusarium fungi and containing low amounts of DON were accessions of the hexaploids A. byzantina, A. fatua, A. sativa, A. sterilis, and the diploid A. wiestii.

The development of resistant varieties and hybrid combinations has been the most effective and economical strategy to control blast disease caused by Magnaporthe oryzae. However, the distribution of major R genes and blast resistance characterization in hybrid rice parents has not been well investigated, resulting in their limited use in hybrid rice blast-resistance breeding. In the present study, 88 elite indica hybrid rice parental lines were evaluated with 30 isolates of M. oryzae collected from the main planting area of indica hybrid rice in China and were characterized for the presence of 11 major resistance genes using molecular markers. The pathogenicity assays showed that four types of hybrid rice parent line showed some resistance to M. oryzae. However, the proportions of highly resistant lines and the mean resistance frequency (RF) varied among the four types, with resistance in decreasing order shown by three-line restorer lines, three-line maintainer lines, two-line sterile lines, and two-line restorer lines. All 88 hybrid rice parental lines carried more than one R gene, but none carried the R genes Pi1 and Pi2. Although Pid3 and Pi9 were present only in three-line restorer lines and Pigm only in three-line maintainer lines, the remaining six R genes (Pib, Pid2, Pi5, Pia, Pi54, and Pita) were present in the four types of hybrid rice parent with significantly different distribution frequencies. The correlation between R genes and resistance reactions was investigated. The results are expected to provide useful information for rational utilization of major R genes in hybrid rice breeding programs.

The genebank at ICRISAT maintains 8020 accessions of sorghum from 16 West and Central African countries. Geographical gaps and diversity were assessed in the collection. Using the passport data of 3991 accessions for which georeferenced data were available, a total of 386 districts (gaps) located in 11 West and Central African countries were identified as geographical gaps. Burkina Faso with 140 and Nigeria with 118 districts were identified as countries with major geographical gaps. The collection of 43 accessions of wild species represented only three species belonging to Sorghum bicolor ssp. drummondii and ssp. verticilliflorum, S. hevisonii, and S. macrochaeta, highlighting the need for collection missions aimed exclusively at enriching the collection of wild relatives. Accessions having characterization data (7630) were used to assess diversity. The first three principal components contributed to > 60% of variation. Maximum diversity was observed in the collection from Nigeria for both qualitative and quantitative traits. Mean values indicated significant differences between basic and intermediate races for the traits studied. Among the races, accessions of guinea-caudatum for qualitative traits and those of caudatum for quantitative traits were highly diverse. The low intensity of the sorghum collection and the many geographical gaps in the collection underline the importance of launching collection missions to fill the gaps, particularly in regions of predominantly guinea sorghums. Genotyping of possible duplicate accessions is needed to identify duplicates in the collection. It is suggested that all passport information including georeferenced data of collection sites should be collected when samples are collected in gaps.

Wheat breeders in Turkey have been developing new varieties since the 1920s, but few studies have evaluated the rates of genetic improvement. This study determined wheat genetic gains by evaluating 22 winter/facultative varieties released for rainfed conditions between 1931 and 2006. The study was conducted at three locations in Turkey during 2008-2012, with a total of 21 test sites. The experimental design was a randomized complete block with four replicates in 2008 and 2009 and three replicates in 2010-2012. Regression analysis was conducted to determine genetic progress over time. Mean yield across all 21 locations was 3.34 t ha^{− 1}, but varied from 1.11 t ha^{− 1} to 6.02 t ha^{− 1} and was highly affected by moisture stress. Annual genetic gain was 0.50% compared to Ak-702, or 0.30% compared to the first modern landmark varieties. The genetic gains in drought-affected sites were 0.75% compared to Ak-702 and 0.66% compared to the landmark varieties. Modern varieties had both improved yield potential and tolerance to moisture stress. Rht genes and rye translocations were largely absent in the varieties studied. The number of spikes per unit area decreased by 10% over the study period, but grains spike^{− 1} and 1000-kernel weight increased by 10%. There were no significant increases in harvest index, grain size, or spike fertility, and no significant decrease in quality over time. Future use of Rht genes and rye translocations in breeding programs may increase yield under rainfed conditions.

Lodging resistance of winter wheat (Triticum aestivum L.) can be increased by late sowing. However, whether grain yield and nitrogen use efficiency (NUE) can be maintained with delayed sowing remains unknown. During the 2013-2014 and 2014-2015 growing seasons, two winter wheat cultivars were sown on three dates (early sowing on October 1, normal sowing on October 8, and late sowing on October 15) to investigate the responses of lodging resistance, grain yield, and NUE to sowing date. No significant differences in lodging resistance, grain yield, or NUE between early and normal sowing were observed. Averaging over the two cultivars and years, postponing the sowing date significantly increased lodging resistance by 53.6% and 49.6% compared with that following early and normal sowing, respectively. Lodging resistance was improved mainly through a reduction in the culm height at the center of gravity and an increase in the tensile strength of the base internode. Late sowing resulted in similar grain yield as well as kernel weight and number of kernels per square meter, compared to early and normal sowing. Averaging over the two cultivars and years, delayed sowing resulted in a reduction in nitrogen uptake efficiency (UPE) by 11.0% and 9.9% compared to early and normal sowing, respectively, owing to reduced root length density and dry matter accumulation before anthesis. An average increase in nitrogen utilization efficiency (UTE) of 12.9% and 11.2% compared to early and normal sowing, respectively, was observed with late sowing owing to a reduction in the grain nitrogen concentration. The increase in UTE offset the reduction in UPE, resulting in equal NUEs among all sowing dates. Thus, sowing later than normal could increase lodging resistance while maintaining grain yield and NUE.

The content of soluble sugar in cowpea (Vigna unguiculata L. Walp.) seeds is important for their acceptability to consumers. The objective of this study was to evaluate the genetic control of soluble sugar content in cowpea using diallel analysis. For this purpose, half-diallel crosses were made among seven diverse parents. The amount of total soluble sugar was estimated by the phenol sulfuric acid reagent method and reducing sugar were measured by the DNS (3,5-dinitrosalicylic acid) reagent method. The total soluble sugar ranged from 11.12 (VYA) to 40.79 mg g^{− 1} (IT93K-693-2) with a mean of 22.31 mg g^{− 1}. Reducing soluble sugar showed a mean value of 9.11 mg g^{− 1} and ranged from 13.61 (TVx 3236) to 4.98 mg g^{− 1} (Lori niébé). Diallel analysis showed that both additive and non-additive gene effects were significant in the genetic control of these traits. However, dominance variance was greater than additive variance for soluble sugar. The traits were controlled mainly by an overdominance model, suggesting the advantage of delaying selection to later generations. Soluble sugar content was found to be highly heritable, with broad-sense heritability ranging from 0.987 to 0.976. Narrow-sense heritability ranged from 0.154 to 0.422 and revealed the lower importance of additive variance. Parents and F₁ hybrids differed significantly on the basis of their general and specific combining abilities, respectively. Recessive alleles had positive effects on total soluble sugar and reducing soluble sugar. These results could help cowpea breeders improve the acceptability of cowpea seeds and cowpea-based foods by appropriate selection.

Faba bean (Vicia faba L.) has an important place in the Ethiopian national diet. It is consumed in various forms and contributes to the improvement of soil fertility. However, its production and productivity are affected by biotic and abiotic constraints. Among the biotic constraints, the emerging faba bean gall disease, caused by Olpidium viciae, is the major and most destructive disease wherever faba bean is grown. Field experiments were conducted at two locations (Farta and Tach Gayint districts) to evaluate the reaction of faba bean varieties to faba bean gall disease and to assess them for yield and yield components during the 2014 and 2015 main cropping seasons. Thirteen faba bean varieties and one local check were planted in three replications using a randomized complete block design. The disease incidence and severity of faba bean gall were recorded (on a 1-9 scale) five times at 10-day intervals. A combined analysis of variance showed a significant difference (P < 0.05) among faba bean varieties with respect to the incidence and severity of gall disease at both locations. Disease incidence, severity, and AUDPC were lowest for variety Tumsa at both locations, but this variety showed high yield only at the Farta location. The highest yields were obtained from varieties Degaga (1157.74 kg ha^{− 1}) and Nc58 (828.97 kg ha^{− 1}) at Farta and Tach Gayint, respectively and these varieties showed low faba bean gall severity and AUDPC. Thus, higher-yielding faba bean varieties such as Degaga and Nc58 are recommended for faba bean production areas in northwestern Ethiopia.