Excellent Agronomic Traits Research Articles

SorghumFDB: sorghum functional genomics database with multidimensional network analysis.

Sorghum (Sorghum bicolor [L.] Moench) has excellent agronomic traits and biological properties, such as heat and drought-tolerance. It is a C4 grass and potential bioenergy-producing plant, which makes it an important crop worldwide. With the sorghum genome sequence released, it is essential to establish a sorghum functional genomics data mining platform. We collected genomic data and some functional annotations to construct a sorghum functional genomics database (SorghumFDB). SorghumFDB integrated knowledge of sorghum gene family classifications (transcription regulators/factors, carbohydrate-active enzymes, protein kinases, ubiquitins, cytochrome P450, monolignol biosynthesis related enzymes, R-genes and organelle-genes), detailed gene annotations, miRNA and target gene information, orthologous pairs in the model plants Arabidopsis, rice and maize, gene loci conversions and a genome browser. We further constructed a dynamic network of multidimensional biological relationships, comprised of the co-expression data, protein–protein interactions and miRNA-target pairs. We took effective measures to combine the network, gene set enrichment and motif analyses to determine the key regulators that participate in related metabolic pathways, such as the lignin pathway, which is a major biological process in bioenergy-producing plants.Database URL: http://structuralbiology.cau.edu.cn/sorghum/index.html.

Seed-Specific Expression of the Arabidopsis AtMAP18 Gene Increases both Lysine and Total Protein Content in Maize.

Lysine is the most limiting essential amino acid for animal nutrition in maize grains. Expression of naturally lysine-rich protein genes can increase the lysine and protein contents in maize seeds. AtMAP18 from Arabidopsis thaliana encoding a microtubule-associated protein with high-lysine content was introduced into the maize genome with the seed-specific promoter F128. The protein and lysine contents of different transgenic offspring were increased prominently in the six continuous generations investigated. Expression of AtMAP18 increased both zein and non-zein protein in the transgenic endosperm. Compared with the wild type, more protein bodies were observed in the endosperm of transgenic maize. These results implied that, as a cytoskeleton binding protein, AtMAP18 facilitated the formation of protein bodies, which led to accumulation of both zein and non-zein proteins in the transgenic maize grains. Furthermore, F1 hybrid lines with high lysine, high protein and excellent agronomic traits were obtained by hybridizing T6 transgenic offspring with other wild type inbred lines. This article provides evidence supporting the use of cytoskeleton-associated proteins to improve the nutritional value of maize.

Isolation and characterization of a wheat – Psathyrostachys huashanica ‘Keng’ 3Ns disomic addition line with resistance to stripe rust

We isolated a wheat germplasm line, 22-2, which was derived from common wheat (Triticum aestivum '7182') and Psathyrostachys huashanica 'Keng' (2n = 2x = 14, NsNs). Genomic composition and homoeologous relationships of 22-2 was analyzed using cytology, genomic in situ hybridization (GISH), EST-SSR, and EST-STS to characterize the alien chromatin in the transfer line. The cytological investigations showed that the chromosome number and configuration were 2n = 44 = 22 II. Mitotic and meiotic GISH using P. huashanica genomic DNA as the probe indicated that 22-2 contained a pair of P. huashanica chromosomes. The genomic affinities of the introduced P. huashanica chromosomes were determined by EST-SSR and EST-STS using multiple-loci markers from seven wheat homoeologous groups between the parents and addition line. One EST-SSR and 17 EST-STS markers, which were located on the homoeologous group 3 chromosomes of wheat, amplified polymorphic bands in 22-2 that were unique to P. huashanica. Thus, these markers suggested that the introduced Ns chromosome pair belonged to homoeologous group 3, so we designated 22-2 as a 3Ns disomic addition line. Based on disease reaction to mixed races (CYR31, CYR32, and Shuiyuan14) of stripe rust in the adult stages, 22-2 was found to have high resistance to stripe rust, which was possibly derived from its P. huashanica parent. Consequently, the new disomic addition line 22-2 could be a valuable donor source for wheat improvement depending on the excellent agronomic traits, especially, the introduction of novel disease resistance genes into wheat during breeding programs.

Characterization of a wheat-Psathyrostachys huashanica Keng 4Ns disomic addition line for enhanced tiller numbers and stripe rust resistance

Exploiting and utilizing excellent gene(s) from wild species has become an essential strategy for wheat improvement. In the disomic addition line 24-6-3, the 4Ns chromosomes from Psathyrostachys huashanica Keng (2n=2x=14, NsNs) carried valuable tiller and strip rust resistance gene(s), which was selected from the progeny of common wheat cv. 7182 and P. huashanica via embryo culture. Cytology, genomic in situ hybridization (GISH), and EST-STS analyses were used to detect the 4Ns chromosome in wheat background and its homoeologous relationship. Cytological studies demonstrated that 24-6-3 contained 44 chromosomes and formed 22 bivalents during meiotic metaphase I. GISH using P. huashanica genomic DNA as a probe indicated that a pair of Ns-chromosomes with strong hybridization signals had been introduced into 24-6-3. Ten EST-STS markers, i.e., BE404973, BE442811, BE446061, BE446076, BE497324, BE591356, BF473854, BG274986, BQ161513 and CD373484, which were located on the homoeologous group 4 chromosomes of wheat, amplified bands unique to P. huashanica in 24-6-3. This indicated the presence of an introgressed P. huashanica Ns chromosome pair belonging to homoeologous group 4, which we designated the 4Ns disomic addition line. After it was inoculated using mixed races of stripe rust in the adult stages, 24-6-3 expressed high stripe rust resistance, which was possibly derived from its P. huashanica parent. Moreover, its increased number of tillers was probably controlled by gene(s) located in P. huashanica chromosome 4Ns. These high levels of disease resistance and excellent agronomic traits make the 24-6-3 line a promising germplasm for breeding in wheat.

Effects of salinity stress on starch morphology, composition and thermal properties during grain development in triticale

He, J.-F., Goyal, R., Laroche, A., Zhao, M.-L. and Lu, Z.-X. 2013. Effects of salinity stress on starch morphology, composition and thermal properties during grain development in triticale. Can. J. Plant Sci. 93: 765–771. Triticale is a man-made cereal crop developed from a cross between wheat and rye. It has excellent agronomic traits for starch production on arid and semi-arid lands. This study investigated the effects of salinity stress on the alterations of starch morphology, composition and physicochemical properties during triticale grain development. Three triticale varieties (AC Certa, AC Ultima and Blue Alta) were treated with three levels of NaCl solutions (50, 100 and 200 mM), termed low salinity stress (LSS), moderate salinity stress (MSS) and high salinity stress (HSS), respectively. Reduction in seed weight and starch content were observed under salinity stress; the values decreased by 9–42% under MSS and 18–51% under HSS. MSS and HSS favored an increase of amylose synthesis and accumulation in triticale starch. Triticale starch synthesized under salinity stress showed a decreased population of small granules and an increased ratio on A-type to B-type granules. MSS and HSS decreased the peak temperature and increased the starch enthalpy, and an inverse relationship between salinity stress and a range of starch gelatinization temperature was also observed. This is the first report demonstrating that starch morphology, composition and thermal properties in triticale grains can be significantly affected by salinity stress.

Effects of salinity stress on starch morphology, composition and thermal properties during grain development in triticale

He, J.-F., Goyal, R., Laroche, A., Zhao, M.-L. and Lu, Z.-X. 2013. Effects of salinity stress on starch morphology, composition and thermal properties during grain development in triticale. Can. J. Plant Sci. 93: 765-771. Triticale is a man-made cereal crop developed from a cross between wheat and rye. It has excellent agronomic traits for starch production on arid and semi-arid lands. This study investigated the effects of salinity stress on the alterations of starch morphology, composition and physicochemical properties during triticale grain development. Three triticale varieties (AC Certa, AC Ultima and Blue Alta) were treated with three levels of NaCl solutions (50, 100 and 200 mM), termed low salinity stress (LSS), moderate salinity stress (MSS) and high salinity stress (HSS), respectively. Reduction in seed weight and starch content were observed under salinity stress; the values decreased by 9-42% under MSS and 18-51% under HSS. MSS and HSS favored an increase of amylose synthesis and accumulation...

Development and Characterization of a Psathyrostachys huashanica Keng 7Ns Chromosome Addition Line with Leaf Rust Resistance

The aim of this study was to characterize a Triticum aestivum-Psathyrostachys huashanica Keng (2n = 2x = 14, NsNs) disomic addition line 2-1-6-3. Individual line 2-1-6-3 plants were analyzed using cytological, genomic in situ hybridization (GISH), EST-SSR, and EST-STS techniques. The alien addition line 2-1-6-3 was shown to have two P. huashanica chromosomes, with a meiotic configuration of 2n = 44 = 22 II. We tested 55 EST-SSR and 336 EST-STS primer pairs that mapped onto seven different wheat chromosomes using DNA from parents and the P. huashanica addition line. One EST-SSR and nine EST-STS primer pairs indicated that the additional chromosome of P. huashanica belonged to homoeologous group 7, the diagnostic fragments of five EST-STS markers (BE404955, BE591127, BE637663, BF482781 and CD452422) were cloned, sequenced and compared. The results showed that the amplified polymorphic bands of P. huashanica and disomic addition line 2-1-6-3 shared 100% sequence identity, which was designated as the 7Ns disomic addition line. Disomic addition line 2-1-6-3 was evaluated to test the leaf rust resistance of adult stages in the field. We found that one pair of the 7Ns genome chromosomes carried new leaf rust resistance gene(s). Moreover, wheat line 2-1-6-3 had a superior numbers of florets and grains per spike, which were associated with the introgression of the paired P. huashanica chromosomes. These high levels of disease resistance and stable, excellent agronomic traits suggest that this line could be utilized as a novel donor in wheat breeding programs.

Water stress during grain development affects starch synthesis, composition and physicochemical properties in triticale

Triticale, a man-made cereal crop developed from a cross between wheat and rye, has excellent agronomic traits to produce starch for bioindustrial applications. The effects of different levels of water stress on expression of starch synthesis genes and starch composition and physicochemical properties were investigated in this study. Three triticale varieties from 5 days post-anthesis were treated with three levels of water stress: low water stress (LWS) at 55–60% of soil moisture, moderate water stress (MWS) at 30–35% soil moisture and severe water stress (SWS) at 10–15% soil moisture. Water stress led to a significant reduction in seed weight at SWS (35–45%). A decrease in starch content was noticeable from MWS onwards and the values were decreased by 42–55% at SWS across all varieties. Such decrease was associated with the reduced expression of starch synthesis genes at 19 days of water stress (DWS). MWS favoured an increase of amylose proportion in triticale starch and it was accompanied by a significant up-regulation of GBSSI expression throughout the grain development. Triticale starch synthesized under water stress showed a reduced population of small granules and an increase of A-type to B-type ratio. SWS caused pitting on starch granules but did not alter the biconcave disc shape of mature granules. An inverse relationship between water stress and a range of starch gelatinization temperature was observed and the MWS environment specifically decreased the peak temperature (Tp) and increased the enthalpy. Our results signify that starch morphology, composition and physicochemical properties in triticale grains could be altered if triticale is grown under drought conditions.

Developing Pusa 5A, a stable indica CMS line with high outcrossing potential

From available germplasm and breeding lines at IARI, we have identified Pusa 150-2, a maintainer with excellent agronomic traits. Pusa 150-2 is a high-yielding semidwarf indica variety with excellent grain quality. When test-crossed with IR58025A, it produced F1 progeny with 100% pollen sterility. The F1 progeny was backcrossed to Pusa 150-2 and a population of approximately 750 BC1 plants was raised. All plants showed 100% pollen sterility under the microscope but segregated for various agronomic characters. Thirty plants showing characters comparable with those of Pusa 150-2 were backcrossed. All the progenies were 100% sterile.

RNAi-directed down-regulation of RSV results in increased resistance in rice (Oryza sativa L.)

Rice stripe disease (RSD), caused by rice stripe virus (RSV), is a serious disease in temperate rice-growing areas. We have created an RNAi construct containing coat protein gene (CP) and disease specific protein gene (SP) sequences from RSV. The RNAi construct was transformed into two susceptible japonica varieties, Suyunuo and Guanglingxiangjing, to develop resistance against RSD. The homozygous progeny of rice plants in the T(5) and T(7) generations containing RNAi constructs, after self-fertilization were strongly resistant to viral infection. RT-PCR indicated that viral replication of SP and CP in the transgenic plants was significantly inhibited. There were no obvious morphological or developmental differences between the transgenic and wild-type plants from seedling stage to maturity. The excellent agronomic traits of these two varieties, such as high yield and good quality were maintained. Suppression of virus genes using RNAi is therefore a practical and effective strategy for controlling viral infection in crops.

Transferring Translucent Endosperm Mutant Gene Wx-mq and Rice Stripe Disease Resistance Gene Stv-b i by Marker-Assisted Selection in Rice ( Oryza sativa)

A high-yielding japonica rice variety, Wuyunjing 7, bred in Jiangsu Province, China as a female parent was crossed with a Japanese rice variety Kantou 194, which carries a rice stripe disease resistance gene Stv-b i and a translucent endosperm mutant gene Wx-mq. From F 2 generations, a sequence characterized amplified region (SCAR) marker tightly linked with Stv-b i and a cleaved amplified polymorphic sequence (CAPS) marker for Wx-mq were used for marker-assisted selection. Finally, a new japonica rice line, Ning 9108, with excellent agronomic traits was obtained by multi-generational selection on stripe disease resistance and endosperm appearance. The utilization of the markers from genes related to rice quality and disease resistance was helpful not only for establishing a marker-assisted selection system of high-quality and disease resistance for rice but also for providing important intermediate materials and rapid selection method for good quality, disease resistance and high yield in rice breeding.

Dwarfism in Brassica napus L. induced by the over-expression of a gibberellin 2-oxidase gene from Arabidopsis thaliana

Gibberellins (GAs) are endogenous hormones that play an important role in regulating plant stature by increasing cell division and elongation in stem internodes. The GA2-oxidase gene from Arabidopsis thaliana (AtGA2ox8) was introduced into Brassica napus L. by Agrobacterium-mediated floral-dip transformation with the aim of decreasing the amount of bioactive GA and hence reducing plant stature. As anticipated, the transgenic plants exhibited dwarf phenotype. Compared with the wild type, the transgenic plants had increased primary branches (by 14.1–15.3%) and siliques (by 10.8–15.2%), which resulted in a significant increase in the seed yield (by 9.6–12.4%). Moreover, the contents of anthocyanin in leaves of 60-day-old transgenic plants was about 9.4-fold higher in winter and about 6.8-fold higher in summer than the wild type. These excellent agronomic traits of the transgenic plants could not only improve the lodging resistance and seed yields, but also protect them against stress. Therefore, the over-expression of AtGA2ox8 might be used to produce dwarf varieties and increase seed yield in Brassica napus L.

Creation of new maize germplasm using alien introgression from Zea mays ssp. mexicana

Zea mays ssp. mexicana, an annual wild relative of maize, has many desirable characteristics for maize improvement. To transfer alien genetic germplasm into maize background, F1 hybrids were generated by using Z. mays ssp. mexicana as the female parent and cultivated maize inbred line Ye515 as the male parent. Alien introgression lines, with a large range of genetic diversity, were produced by backcross and successive self-pollinations. A number of alien introgression lines with the predominant traits of cultivated maize were selected. Genomic in situ hybridization (GISH) proved that small chromosome segments of Z. mays ssp. mexicana had been integrated into the maize genome. Some outstanding alien introgression lines were evaluated in performance trials which showed 54.6% hybrids had grain yield greater than that of hybrid check Yedan12 which possessed 50% Ye515 parentage, and 17.1, 9.9% hybrids had grain yield competitive or greater than those of Nongda108 and Zheng958, which were elite commercial hybrids in China, respectively. The results indicated that some of the introgression lines had excellent agronomic traits and combining ability for maize cultivar, and demonstrated that Z. mays ssp. mexicana was a valuable source for maize breeding, and could be used to broaden and enrich the maize germplasm.

Production and analysis of transgenic wheat (Triticum aestivum L.) with improved insect resistance by the introduction of cowpea trypsin inhibitor gene

The cowpea trypsin inhibitor gene (CpTI) and neomycin phosphotransferase gene (nptII) were introduced into the embryonic callus cells of immature embryos of wheat elite line Shannong 995604 using Agrobacterium-mediated gene transfer. Independent plantlets were regenerated from kanamycin-resistant calli. PCR and real time PCR analysis, PCR-Southern and Southern blot hybridization indicated that there were three independently-dervied transgenic plants viz. transformed-I, II and III (T-I, T-II and T-III). The segregation of CpTI in the transgenic wheat progenies of T-Iand T-III were consistent with Mendelian inheritance. Resistance to the storage insect pest of wheat viz. the grain moth (Sitotroga cerealella Olivier) was improved significantly in seeds of the three transgenic wheat T2 lines obtained from T1 PCR-positive plants. The frequency of moth-eaten seed from T-I, T-IIand T-III was reduced 66.76%, 62.48% and 43.59% respectively. The investigation of agronomic traits of the three transgenic wheat T1 PCR-positive plants revealed that the three transgenic lines had excellent agronomic traits. They provide good germplasm resource for wheat genetic improvement.

(441) Evaluation of Three Grafting Methods for Propagating Soursop (Annona muricata L.) in the Dry Tropic Region of Mexico

Soursop (Annonamuricata L.) is reproduced by seeds from `Criollo' cultivars in Mexico. The replication of desirable agronomic traits is difficult when selected plants are from sexual reproduction. The heterogeneity of plants is observed as taller trees, irregular fresh fruit yield, variable fruit quality, different insect pests, disease susceptibilities, and lower number of plants per hectare. There is an extended time period for recovering investments and commericialization problems due to fruit quality and price. Vegetative propagation is an alternative for reducing the heterogeneity of soursop trees. Three grafting methods were evaluated for propagating soursop in the dry tropic region of Colima, Mexico: 1) splice side graft; 2) wedge graft; and 3) bud graft. The experiment was carried out on the Tecoman Campus of the Universidad de Colima. Rootstocks were from 8-month-old healthy plants, 1-m tall and 1-cm diameter, obtained from `Criollo' seedlings, and the scions were obtained from a healthy 10-year-old `Sin Fibra' donor tree. This donor tree was selected for its excellent agronomic traits and fruit yield. Vigorous and terminal scions were used, disinfected with fungicide, and used the same day of excision. The experiment was distributed under a completely randomized design. Splice side grafting had 67% success after 60 days, while wedge grafting and bud grafting had 0% success.

Inheritance of photoperiod sensitive genic male sterility and breeding of photoperiod sensitive genic male-sterile lines in rice (Oryza sativa L.) through anther culture

The fertility segregations of F1, F2, BCF1 descended from crosses between PSGMR and japonica varieties, and F1's anther cultured homozygous diploid pollen plant populations (H2) were studied to reveal the genetic mechanism of photoperiod sensitive genic male sterility in PSGMR under natural daylight length at Shanghai. Rate of bagged seed-setting was used as an indicator of fertility. Fifteen F1 showed complete fertility similar to their parents. The ratio of completely sterile plants to fertile plants in fifteen F2 and four BCF1 was 1:15 and 1:3, respectively. The ratio of completely sterile to fertile diploid pollen plants in nine diploid populations (H2) was 1:3. These results demonstrated that the photoperiod sensitive genic male sterility in PSGMR was governed by two pairs of independent major recessive genes. There were no significant fertility segregations in hybrids F1 and selfed F2 between Nongken 58S and its derivatives 7001S, 5088S, 5047S and M105-9S, indicating that the photoperiod sensitive genic male-sterile genes in Nongken 58S were allelic to those in its derivatives. Several photoperiod sensitive genic male-sterile diploid pollen lines were bred from anther cultured homozygous diploid populations (H2) in about a three-year period. Most of these diploid lines showed significant fertility transformation and stable complete sterility from 5 August to 5 September, excellent agronomic traits and high resistance to blast and bacterial leaf blight.