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The undirected graph, exchanged hypercube $EH(s,t)$, is a variant of hypercube proposed by Loh et al. It is obtained by removing some links from $(s+t+1)$-dimensional hypercube. It retains many excellent properties, so many people have studied its reliability and fault tolerance. In this paper, combining the structure connectivity and substructure connectivity of graphs proposed not long ago, we obtain its $P_k$-path, $C_{2l}$-cycle and $K_{1,r}$-star structure connectivity and substructure connectivity where $2\le k,r\le s-1\le t-1$ and $6\le 2l\le s-1\le t-1$; we also establish $\kappa ^s(EH(s,t);C_4)$ for $5\le s\le t$ and the upper bound of $\kappa (EH(s,t);C_4)$ for $4\le s\le t$.

The S-structure connectivity κ ( G ; S ) and S-substructure connectivity κ s ( G ; S ) of graph G with structure graph S, which are newly proposed in recent years, can better measure fault tolerance of networks. In this paper, we study κ ( B H n ; S ) and κ s ( B H n ; S ) of n-dimensional balanced hypercube B H n , which is a relatively popular network topology proposed recently, for S ∈ { P k , C 6 α , K 1 , r } where 4 ≤ k ≤ n , 6 ≤ 6 α ≤ n and 4 ≤ r ≤ 5 .

Grain size is a major determinant of grain yield in sorghum and other cereals. Over 100 quantitative trait loci (QTLs) of grain size have been identified in sorghum. However, no gene underlying any grain size QTL has been cloned. Here, we describe the fine mapping and cloning of one grain size QTL. From an F8 recombinant inbred line population derived from a cross between inbred lines 654 and LTR108, we identified 44 grain size QTLs. One QTL, qTGW1a, was detected consistently on the long arm of chromosome 1 in the span of 4 years. Using the extreme recombinants from an F2:3 fine-mapping population, qTGW1a was delimited within a ~33 kb region containing three predicted genes. One of them, SORBI_3001G341700, predicted to encode a G-protein γ subunit and homologous to GS3 in rice, is likely to be the causative gene for qTGW1a. qTGW1a appears to act as a negative regulator of grain size in sorghum. The functional allele of the putatively causative gene of qTGW1a from inbred line 654 decreased grain size, plant height, and grain yield in transgenic rice. Identification of the gene underlying qTGW1a advances our understanding of the regulatory mechanisms of grain size in sorghum and provides a target to manipulate grain size through genome editing.

Low soil moisture is a major abiotic stress wide spread in arid and semi-arid regions, limiting both seed germination and seedling establishment. Deep-seeding technique allows seeds to use the moisture in deep soil, however, most sorghum seeds cannot penetrate soil layer of 10 cm or deeper. To develop sorghum varieties tolerant to deep-seeding, it is necessary to identify promising accessions with good agronomic traits and tolerance to deep-seeding. A high throughput hydroponic method was developed to screen sorghum accessions with long mesocotyl under dark conditions. This method revealed large genetic variations for mesocotyl length in the panel of 105 sorghum accessions, which were validated by soil culture and deep-seeding experiments. The lines with long mesocotyl under hydroponic culture had good seedling establishments in deep-seeding experiments, while the lines with short mesocotyl length could not emerge. Compared to conventional sand or soil cultural methods, the hydroponic culture was highly efficient that requires less time, space, and labor. The mesocotyl lengths of screened sorghum accessions under the newly developed hydroponic method were highly correlated with soil culture and germination rate under deep-seeding in soil. As an efficient screening tool for the mesocotyl lengths under soil culture and the seedling emergence rates from deep soil layer, the hydroponic culture method can be easily integrated in breeding programs targeting deep-seeding tolerance. Breeding for long mesocotyl sorghum varieties may lead to good seedling establishments under arid and semi-arid regions.

Functional chloroplast generation depends on the precise coordination of gene expression between the plastid and the nucleus and is essential for plant growth and development. In this study, a rice (Oryza sativa) mutant that exhibited albino and seedling-lethal phenotypes was isolated from a60Co-irradiated rice population. The mutant gene was identified as an ortholog of the Arabidopsis plastid transcriptionally active chromosome protein 2 (pTAC2) gene, and the mutant strain was designated osptac2. Sequence and transcription analyses showed that OspTAC2 encodes a putative chloroplast protein consisting of 10 pentratricopeptide repeat (PPR) domains and a C-terminal small MutS-related (SMR) domain. Cytological observations via microscopy showed that the OspTAC2-green fluorescent fusion protein is localized in the chloroplasts. Transmission electron microscopy revealed that the chloroplast of the osptac2 mutant lacks an organized thylakoid membrane. The transcript levels of all investigated PEP (plastid-encoded RNA polymerase)-dependent genes were dramatically reduced in the osptac2 mutant, whereas the transcript levels of NEP (nuclear-encoded polymerase)-dependent genes were increased. These results suggest that OspTAC2 plays a critical role in chloroplast development and indicate that the molecular function of the OspTAC2 gene is conserved in rice and Arabidopsis.

Serine hydroxymethyltransferase (SHMT) is important for one carbon metabolism and photorespiration in higher plants for its participation in plant growth and development, and resistance to biotic and abiotic stresses. A rice serine hydroxymethyltransferase gene, OsSHM1, an ortholog of Arabidopsis SHM1, was isolated using map-based cloning. The osshm1 mutant had chlorotic lesions and a considerably smaller, lethal phenotype under natural ambient CO2 concentrations, but could be restored to wild type with normal growth under elevated CO2 levels (0.5% CO2 ), showing a typical photorespiratory phenotype. The data from antioxidant enzymes activity measurement suggested that osshm1 was subjected to significant oxidative stress. Also, OsSHM1 was expressed in all organs tested (root, culm, leaf, and young panicle) but predominantly in leaves. OsSHM1 protein is localized to the mitochondria. Our study suggested that molecular function of the OsSHM1 gene is conserved in rice and Arabidopsis.

Contamination of steroidal estrogens in the environment has raised a great public concern, and therefore, developing an effective method for removal of trace amount of environmental estrogens is necessary. In this study, two estrogen-degrading bacteria were isolated from activated sludge and were identified as strain Sphingomonas sp. AHC-F and strain Sphingobium sp. AX-B. They were capable of utilizing estrone (E1) and 17s-estradiol (E2) as sole carbon and energy source. Cell immobilization technique was applied to these two estrogen-degrading bacteria. Confocal laser-scanning microscopy images with live and dead staining of entrapped bacterial cells showed that most bacteria were present inside the porous structure and were mostly viable after immobilization procedures. Batch estrogen degradation study showed that immobilized strains AHC-F and AX-B could effectively degrade 2 mg/L of E2 and its metabolite E1. Immobilized bacteria column reactors using pure culture of strain AHC-F were set up for continuous-flow removal of 850 ng/L of E2 in the influent. The removal efficiency of E2 and equivalent estrogenic quantity of E2 (EEQ) could achieve 94 and 87% under 12 h hydraulic retention time (HRT), respectively. Increasing HRT could further improve the removal efficiency of EEQ. When the HRT increased to 72 h, the effluent concentrations of E2 and E1 were not detectable by gas chromatography-mass spectrometry. Our results also proved that most of the estrogen removal was due to biodegradation. This study has demonstrated the potential use of immobilized bacteria technique for the removal of environmental estrogens.

Serine hydroxymethyltransferase (SHMT) is important for one carbon metabolism and photorespiration in higher plants for its participation in plant growth and development, and resistance to biotic and abiotic stresses. A rice serine hydroxymethyltransferase gene, OsSHM1, an ortholog of Arabidopsis SHM1, was isolated using map-based cloning. The osshm1 mutant had chlorotic lesions and a considerably smaller, lethal phenotype under natural ambient CO2 concentrations, but could be restored to wild type with normal growth under elevated CO2 levels (0.5% CO2 ), showing a typical photorespiratory phenotype. The data from antioxidant enzymes activity measurement suggested that osshm1 was subjected to significant oxidative stress. Also, OsSHM1 was expressed in all organs tested (root, culm, leaf, and young panicle) but predominantly in leaves. OsSHM1 protein is localized to the mitochondria. Our study suggested that molecular function of the OsSHM1 gene is conserved in rice and Arabidopsis.