SYL3-k increases style length and yield of F1 seeds via enhancement of endogenous GA4 content in Oryza sativa L. pistils.

KEY MESSAGE: SYL3-k allele increases the outcrossing rate of male sterile line and the yield of hybrid F1 seeds via enhancement of endogenous GA4 content in Oryza sativa L. pistils. The change in style length might be an adaptation of rice cultivation from south to north in the northern hemisphere. The style length (SYL) in rice is one of the major factors influencing the stigma exertion, which affects the outcross rate of male sterile line and the yield of hybrid F1 seeds. However, the biological mechanisms underlying SYL elongation remain elusive. Here, we report a map-based cloning and characterisation of the allele qSYL3-k. The qSYL3-k allele encodes a MADS-box family transcription factor, and it is expressed in various rice organs. The qSYL3-k allele increases SYL via the elongation of cell length in the style, which is associated with a higher GA4 content in the pistil. The expression level of OsGA3ox2 in pistils with qSYL3-k alleles is significantly higher than that in pistils with qSYL3-n allele on the same genome background of Nipponbare. The yield of F1 seeds harvested from plants with 7001SSYL3-k alleles was 16% higher than that from plants with 7001SSYL3-n allele. The sequence data at the qSYL3 locus in 136 accessions showed that alleles containing the haplotypes qSYL3AA, qSYL3AG, and qSYL3GA increased SYL, whereas those containing the haplotype qSYL3GG decreased it. The frequency of the haplotype qSYL3GG increases gradually from the south to north in the northern hemisphere. These findings will facilitate improvement in SYL and yield of F1 seeds henceforward.

Genomics, expression, and function analyses of XB3 family genes in cotton.

XANTHOMONAS RESISTANCE 21-binding protein3 (XB3) is the first characterized XA21 interacting protein required for plant immunity. We isolated GhXB32A that is similar to XBAT32 and was induced during inoculation of Verticillium dahliae in cotton. 32 putative XB3 family genes were identified in G. hirsutum, G. arboreum, and G. raimondii. Cis-Acting elements related to growth, stresses, and phytohormone were detected in the promoter regions. GhXB3s were ubiquitously expressed in different cotton tissues with different patterns. Most GhXB3s were down-regulated by cold stress, but up-regulated by heat, salt, PEG, V. dahliae, ethylene, and some were up-regulated by SA or MeJA. Silencing GhXB32A and GhXB32D greatly improved resistance to Verticillium wilt, while silencing GhXB35A(D) or GhXB37A(D) made them more susceptible to V. dahliae. The interacting proteins of GhXB32A and GhXB32D were functionally enriched in response to abiotic and/or biotic stresses, and photosynthesis. XB3 family genes are potential stress resistance genes for cotton improvement.

OsSYL2AA , an allele identified by gene-based association, increases style length in rice (Oryza sativa L.).

Stigma characteristics are important factors affecting the seed yield of hybrid rice per unit area. Natural variation of stigma characteristics has been reported in rice, but the genetic basis for this variation is largely unknown. We performed a genome-wide association study on three stigma characteristics in six environments using 1.3 million single-nucleotide polymorphism (SNPs) characterized in 353 diverse accessions of Oryza sativa. An abundance of phenotypic variation was present in the three stigma characteristics of these collections. We identified four significant SNPs associated with stigma length, 20 SNPs with style length (SYL), and 17 SNPs with the sum of stigma and style length, which were detected repeatedly in more than four environments. Of these SNPs, 28 were novel. We identified two causal gene loci for SYL, OsSYL3 and OsSYL2; OsSYL3 was co-localized with the grain size gene GS3. The SYL of accessions carrying allele OsSYL3AA was significantly longer than that of those carrying allele OsSYL3CC . We also demonstrated that the outcrossing rate of female parents carrying allele OsSYL2AA increased by 5.71% compared with that of the isogenic line carrying allele OsSYL2CC in an F1 hybrid seed production field. The allele frequencies of OsSYL3AA and OsSYL2AA decreased gradually with an increase in latitude in the Northern Hemisphere. Our results should facilitate the improvement in stigma characteristics of parents of hybrid rice.

Association analysis between constructed SNPLDBs and GCA effects of 9 quality-related traits in parents of hybrid rice (Oryza sativa L.).

BACKGROUND: The general combining ability (GCA) of parents in hybrid rice affects not only heterotic level of grain yield and other important agronomic traits, but also performance of grain quality traits of F2 bulk population which is the commodity consumed by humans. In order to make GCA improvement for quality traits in parents of hybrid rice by molecular marker assisted selection feasible, genome-wide GCA loci for quality traits in parents were detected through association analysis between the effects of GCA and constructed single nucleotide polymorphism linkage disequilibrium blocks (SNPLDBs), by using unhusked rice grains harvested from F1 plants of 48 crosses of Indica rice and 78 crosses of Japonica rice. GCA-SNPLDBs association analysis. RESULTS: Among the 8 CMS and 6 restorer lines of indica rice subspecies, CMS lines Zhenpin A, Zhenshan97 A, and 257A, and restorers Kanghui98, Minghui63 and Yanhui559 were recognized as good general combiners based on their GCA effect values for the 9 quality traits (brown rice rate, milled rice rate, head rice rate, percentage of chalky grains, chalky area size, chalkiness degree, gelatinization temperature, gel consistency and amylose content). Among the 13 CMS and 6 restorer lines of japonica rice subspecies, CMS 863A, 6427A and Xu 2A, and restorers C418, Ninghui8hao and Yunhui4hao showed elite GCA effect values for the 9 traits. GCA-SNPLDB association analysis revealed 39 significant SNPLDB loci associated with the GCA of the 9 quality-related traits, and the numbers of SNPLDB loci located on chromosome 1, 2, 3, 4, 5, 8, 9, 11 and 12 were 1, 4, 3, 9, 6, 5, 5, 4 and 2, respectively. Number of superior GCA alleles for the 9 traits among the 33 parents ranged from 1 to 26. CONCLUSIONS: Thirty-nine significant SNPLDBs loci were identified associated with the GCA of 9 quality-related traits, and the superior SNPLDB alleles could be used to improve the GCA of parents for the traits in the future by molecular marker assisted selection. The genetic basis of trait GCA in parents is different from that of trait itself.

Favorable Alleles of GRAIN-FILLING RATE1 Increase the Grain-Filling Rate and Yield of Rice.

Hybrid rice (Oryza sativa) has been cultivated commercially for 42 years in China. However, poor grain filling still limits the development of hybrid japonica rice. We report here the map-based cloning and characterization of the GRAIN-FILLING RATE1 (GFR1) gene present at a major-effect quantitative trait locus. We elucidated and confirmed the function of GFR1 via genetic complementation experiments and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene editing in combination with genetic and molecular biological analyses. In addition, we conducted haplotype association analysis to mine the elite alleles of GFR1 among 117 rice accessions. We observed that GFR1 was constitutively expressed and encoded a membrane-localized protein. The allele of the rice accession Ludao (GFR1 Ludao) improved the grain-filling rate of rice by increasing Rubisco initial activity in the Calvin cycle. Moreover, the increased expression of the cell wall invertase gene OsCIN1 in the near isogenic line NIL-GFR1 Ludao promoted the unloading of Suc during the rice grain-filling stage. A yeast two-hybrid assay indicated that the Rubisco small subunit interacts with GFR1, possibly in the regulation of the rice grain-filling rate. Evaluation of the grain-filling rate and grain yield of F1 plants harboring GFR1 Ludao and the alleles of 20 hybrids widely cultivated commercially confirmed that favorable alleles of GFR1 can be used to further improve the grain-filling rate of hybrid japonica rice.

Mining of favorable alleles for seed reserve utilization efficiency in Oryza sativa by means of association mapping.

BACKGROUND: Wet direct-seeded rice is a possible alternative to conventional puddled transplanted rice; the former uses less water and reduces labor requirements. Improving seed reserve utilization efficiency (SRUE) is a key factor in facilitating the application of this technology. However, the QTLs controlling this trait are poorly investigated. In this study, a genome-wide association study (GWAS) was conducted using a natural population composed of 542 accessions of rice (Oryza sativa L.) which were genotyped using 266 SSR markers. Large phenotypic variations in SRUE were found in the studied population. RESULTS: The average SRUE over 542 accessions across two years (2016 and 2017) was 0.52 mg.mg- 1, ranging from 0.22 mg.mg-1 to 0.93 mg.mg- 1, with a coefficient of variation of 22.66%. Overall, 2879 marker alleles were detected in the population by 266 pairs of SSR markers, indicating a large genetic variation existing in the population. Using general linear model method, 13 SSR marker loci associated with SRUE were detected and two (RM7309 and RM434) of the 13 loci, were also detected using mixed linear model analyses, with percentage of phenotypic variation explained (PVE) greater than 5% across two years. The 13 association loci (P < 0.01) were located on all chromosomes except chromosome 11, with PVE ranging from 5.05% (RM5158 on chromosome 5) to 12% (RM297 on chromosome 1). Association loci RM7309 on chromosome 6 and RM434 on chromosome 9 revealed by both models were detected in both years. Twenty-three favorable alleles were identified with phenotypic effect values (PEV) ranging from 0.10 mg.mg- 1 (RM7309-135 bp on chromosome 9) to 0.45 mg.mg- 1 (RM297-180 bp on chromosome 2). RM297-180 bp showed the largest phenotypic effect value (0.44 mg.mg- 1 in 2016 and 0.45 mg.mg- 1 in 2017) with 6.72% of the accessions carrying this allele and the typical carrier accession was Manyedao, followed by RM297-175 bp (0.43 mg.mg- 1 in 2016 and 0.44 mg.mg- 1 in 2017). CONCLUSION: Nine novel association loci for SRUE were identified, compared with previous studies. The optimal parental combinations for pyramiding more favorable alleles for SRUE were selected and could be used for breeding rice accessions suitable for wet direct seeding in the future.

Favorable alleles mining for gelatinization temperature, gel consistency and amylose content in Oryza sativa by association mapping.

BACKGROUND: Improving the gelatinization temperature (GT), gel consistency (GC) and amylose content (AC) for parental grain eating and cooking qualities (ECQs) are key factors for enhancing average grain ECQs for hybrid japonica rice. RESULTS: In this study, a genome-wide association mapping (GWAS) for ECQs was performed on a selected sample of 462 rice accessions in 5 environments using 262 simple sequence repeat markers. We identified 10 loci and 27 favorable alleles for GT, GC and AC, and some of these loci were overlapped with starch synthesis-related genes. Four SSR loci for the GT trait were distributed on chromosomes 3, 5, 8, and 9, of which two SSR loci were novel. Two SSR loci associated with the GC trait were distributed on chromosomes 3 and 6, although only one SSR locus was novel. Four SSR loci associated with the AC trait were distributed on chromosomes 3, 6, 10, and 11, of which three SSR loci were novel. The novel loci RM6712 and RM6327 were simultaneously identified in more than 2 environments and were potentially reliable QTLs for ECQs, with 15 parental combinations being predicted. These QTLs and parental combinations should be used in molecular breeding to improve japonica rice average ECQs. CONCLUSIONS: Among the 10 SSR loci associated with GT, GC and AC for grain ECQs detected in 27 favorable alleles, the favorable allele RM3600-90bp on chromosome 9 could significantly reduce GT, RM5753-115bp on chromosome 6 could significantly increase GC, and RM6327-230bp on chromosome 11 could significantly reduce AC in hybrid japonica rice mixed rice samples.

Mining of favorable alleles for lodging resistance traits in rice (oryza sativa) through association mapping.

MAIN CONCLUSION: Fourteen new quantitative trait loci (QTLs) and ten favorable alleles were identified for lodging resistance traits in a natural population of rice. Parental combinations were designed to improve lodging resistance. Lodging is one of the most critical constraints to rice yield, and therefore, mining favorable alleles for lodging resistance traits is imperative for the advancement of cultivated rice and selection for market demand. This investigation was performed on a selected sample of 521 rice cultivars using 262 SSR markers in 2016 and 2017. Lodging resistance traits were evaluated by plant height (PH), stem length (SL), stem diameter (SD), anti-thrust per stem (AT/S), and stem index (SI), with AT/S, used as the lodging resistance index. A genome-wide association map was generated by combining phenotypic and genotypic data. Eight subpopulations were found by structure software, and the linkage disequilibrium (LD) ranged from 30 to 80 cM. Identification of 68 marker-trait associations (MTAs) linking in 64 SSR markers for five traits was done. QTL were detected, including 15 for PH, 14 for SL, 14 for SD, 7 for AT/S, and 18 for SI. A number of favorable alleles were also discovered, including 22, 24, 19, 12, and 28 alleles for PH, SL, SD, AT/S, and SI, respectively. These favorable alleles might be used to design parental combinations, and the predictable results found by relieving the favorable alleles per QTL. The accessions containing favorable alleles for lodging resistant traits mined in this study could be useful for breeding superior rice cultivars.

Both maternally and paternally imprinted genes regulate seed development in rice.

Genetic imprinting refers to the unequal expression of paternal and maternal alleles of a gene in sexually reproducing organisms, including mammals and flowering plants. Although many imprinted genes have been identified in plants, the functions of these imprinted genes have remained largely uninvestigated. We report genome-wide analysis of gene expression, DNA methylation and small RNAs in the rice endosperm and functional tests of five imprinted genes during seed development using Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated gene9 (CRISPR/Cas9) gene editing technology. In the rice endosperm, we identified 162 maternally expressed genes (MEGs) and 95 paternally expressed genes (PEGs), which were associated with miniature inverted-repeat transposable elements, imprinted differentially methylated loci and some 21-22 small interfering RNAs (siRNAs) and long noncoding RNAs (lncRNAs). Remarkably, one-third of MEGs and nearly one-half of PEGs were associated with grain yield quantitative trait loci. Most MEGs and some PEGs were expressed specifically in the endosperm. Disruption of two MEGs increased the amount of small starch granules and reduced grain and embryo size, whereas mutation of three PEGs reduced starch content and seed fertility. Our data indicate that both MEGs and PEGs in rice regulate nutrient metabolism and endosperm development, which optimize seed development and offspring fitness to facilitate parental-offspring coadaptation. These imprinted genes and mechanisms could be used to improve the grain yield of rice and other cereal crops.

Identification of putative markers linked to grain plumpness in rice (Oryza sativa L.) via association mapping.

BACKGROUND: Poor grain plumpness (GP) is one of the main constraints to reaching the yield potential of hybrid rice. RESULTS: In this study, the GP of 177 rice varieties was investigated in three locations across 2 years. By combining the genotype data of 261 simple sequence repeat (SSR) markers, association mapping was conducted to identify the marker-GP association loci. Among 31 marker-GP association loci detected in two or more environments and determined using general linear model (GLM) analyses, seven association loci were also detected using mixed linear model (MLM) analyses. The seven common loci detected by the two analytical methods were located on chromosomes 2, 3 (2), 7, 8 and 12 (2) and explained 7.24~22.28% of the variance. Of these 7 association loci, five markers linked to GP were newly detected: RM5340 on Chr2, RM5480 and RM148 on Chr3, RM1235 on Chr8, and RM5479 on Chr12. CONCLUSIONS: Five marker-GP association loci were newly detected using both the GLM and MLM analytical methods. Elite allele RM505-170 bp had the highest average phenotypic effect on increasing the GP, and the typical carrier variety was 'Maozitou'. Based on the distribution of the elite alleles among the carrier varieties, the top 10 parental combinations for improving the GP in rice via cross-breeding were predicted.

[Study on the Prediction of Germination Rate of Rice Seeds with Continuous Polarization Spectroscopy].

With respect to the problem of long period and low precision in using traditional methods to predict rice seeds germination rate, a novel method based on continuous polarization spectroscopy was proposed to achieve rapid and nondestructive prediction .The paper set different aging rice seeds as prediction targets and ten minutes as prediction time, using polarizer to modulate optical fiber collimating light source to linearly polarized light which issuing into rice seeds extract vertically before rotating the analyser every 5 degrees . The transmission spectrum was predicted through the optical fiber spectrometer. After normalization pretreatment to the polarization spectrum, the article gave the characteristics of polarization angel and wavelength by 0 degree, 5 degrees, 25 degrees, 620, 788 and 576 nm according to the contribution of polarization angel and wavelength when predicting different germination rate rice seeds and inputted obtained continuous polarization spectrum by wavelength, polarization angel, transmissivity to construct rice seeds germination rate prediction model using three modeling methods to build rice seeds germination rate prediction model in comparison, including Partial Least Squares Regression (PLSR), Back Propagation Neural Network (BPNN) and Radial Basis Function Neural Network (RBFNN).1 520 sets of experimental data were measured in total at different polarization angels through using rice seeds with different aging days (0, 2, 4, 6) respectively, setting 912 sets of data as calibration set and 608 sets of data as predicion set. The modeling results show that RBF model's prediction accuracy is the highest. Its correlation coefficient is 0.976; the mean square is 0.785; and the average relative error is 0.85%. The research results show that the continuous polarization spectroscopy technique through multidimension spectral information can achieve rapid and accurate prediction of rice seeds germination rate.

Study on the Detection of Rice Seed Germination Rate Based on Infrared Thermal Imaging Technology Combined with Generalized Regression Neural Network.

On the basis of the differences in physiology and physics of rice seed with different aging time, the paper proposes a fast and nondestructive method which is based on infrared thermal imaging technology and generalized regression neural network to detect the germination rate of rice seed. This method solves the problems of long experimental period, complex operations and other disadvantages of the traditional method which is used to detect germination rate. When the temperature is 45 ℃ and humidity is 90%, the rice seeds are aged for 0, 1, 2, 3, 4, 5, 6 and 7 d respectively to get rice seeds of different germination rate. The data of 144 groups was extracted from the germ of rice seed. This data was divided into two groups randomly: the calibration set was 96 groups and the prediction set was 48 groups. Through analyzing and comparing the differences of infrared thermal image of rice seeds of different aging days, the relationship in physics and physiology between germination rate of rice seed and infrared thermal images was revealed. The infrared prediction model for germination rate of rice seed was established by combining partial least squares algorithm, Back Propagationneural network and General regression neural network. The result shows that the optimal germination rate model is built with GRNN. In this model, the correlation coefficient (RC) and standard deviation (SEC) of calibration sets are 0.932 0 and 2.056 0. At the same time, the correlation coefficient (RP) and standard deviation (SEP) of prediction sets are 0.900 3 and 4.101 2. The relevance reaches a higher level and the standard deviation is small. Therefore, the experiment shows that combining infrared thermal imaging technology with GRNN to study germination rate of rice seed is feasible. The model has a higher accuracy in terms of rapid determination of the germination rate of rice seed.

Genetic diversity and association mapping of seed vigor in rice (Oryza sativa L.).

Seed vigor is closely related to direct seeding in rice (Oryza sativa L.). Previous quantitative trait locus (QTL) studies for seed vigor were mainly derived from bi-parental segregating populations and no report from natural populations. In this study, association mapping for seed vigor was performed on a selected sample of 540 rice cultivars (419 from China and 121 from Vietnam). Population structure was estimated on the basis of 262 simple sequence repeat (SSR) markers. Seed vigor was evaluated by root length (RL), shoot length (SL) and shoot dry weight in 2011 and 2012. Abundant phenotypic and genetic diversities were found in the studied population. The population was divided into seven subpopulations, and the levels of linkage disequilibrium (LD) ranged from 10 to 80 cM. We identified 27 marker-trait associations involving 18 SSR markers for three traits. According to phenotypic effects for alleles of the detected QTLs, elite alleles were mined. These elite alleles could be used to design parental combinations and the expected results would be obtained by pyramiding or substituting the elite alleles per QTL (apart from possible epistatic effects). Our results demonstrate that association mapping can complement and enhance previous QTL information for marker-assisted selection and breeding by design.

Association mapping of yield-related traits and SSR markers in wild soybean (Glycine soja Sieb. and Zucc.).

Wild soybean, the progenitor of cultivated soybean, is an important gene pool for ongoing soybean breeding efforts. To identify yield-enhancing quantitative trait locus (QTL) or gene from wild soybean, 113 wild soybeans accessions were phenotyped for five yield-related traits and genotyped with 85 simple sequence repeat (SSR) markers to conduct association mapping. A total of 892 alleles were detected for the 85 SSR markers, with an average 10.49 alleles; the corresponding PIC values ranged from 0.07 to 0.92, with an average 0.73. The genetic diversity of each SSR marker ranged from 0.07 to 0.93, with an average 0.75. A total of 18 SSR markers were identified for the five traits. Two SSR markers, sct_010 and satt316, which are associated with the yield per plant were stably expressed over two years at two experimental locations. Our results suggested that association mapping can be an effective approach for identifying QTL from wild soybean.

Genome-Wide Association Analysis Unravels New Quantitative Trait Loci (QTLs) for Eight Lodging Resistance Constituent Traits in Rice (Oryza sativa L.).

Lodging poses a significant challenge to rice yield, prompting the need to identify elite alleles for lodging resistance traits to improve cultivated rice varieties. In this study, a natural population of 518 rice accessions was examined to identify elite alleles associated with plant height (PH), stem diameter (SD), stem anti-thrust (AT/S), and various internode lengths (first (FirINL), second (SecINL), third (ThirINL), fourth (ForINL), and fifth (FifINL) internode lengths). A total of 262 SSR markers linked to these traits were uncovered through association mapping in two environmental conditions. Phenotypic evaluations revealed striking differences among cultivars, and genetic diversity assessments showed polymorphisms across the accessions. Favorable alleles were identified for PH, SD, AT/S, and one to five internode lengths, with specific alleles displaying considerable effects. Noteworthy alleles include RM6811-160 bp on chromosome 6 (which reduces PH) and RM161-145 bp on chromosome 5 (which increases SD). The study identified a total of 42 novel QTLs. Specifically, seven QTLs were identified for PH, four for SD, five for AT/S, five for FirINL, six for SecINL, five for ThirINL, six for ForINL, and four for FifINL. QTLs qAT/S-2, qPH2.1, qForINL2.1, and qFifINL exhibited the most significant phenotypic variance (PVE) of 3.99% for the stem lodging trait. AT/S, PH, ForINL, and FifINL had additive effects of 5.31 kPa, 5.42 cm, 4.27 cm, and 4.27 cm, respectively, offering insights into eight distinct cross-combinations for enhancing each trait. This research suggests the potential for crossbreeding superior parents based on stacked alleles, promising improved rice cultivars with enhanced lodging resistance to meet market demands.

Determination of the genetic architecture of seed size and shape via linkage and association analysis in soybean (Glycine max L. Merr.).

Seed-size traits, which are controlled by multiple genes in soybean, play an important role in determining seed yield, quality and appearance. However, the molecular mechanisms controlling the size of soybean seeds remain unclear, and little research has been done to investigate these mechanisms. In this study, we performed a genetic analysis to determine the genetic architecture of soybean seed size and shape via linkage and association analyses. We used 184 recombinant inbred lines (RILs) and 219 cultivated soybean accessions to evaluate seed length, seed width and seed height as seed-size traits, and their ratios of these values as seed-shape traits. Our results showed that all six traits had high heritability ranging from 92.46 to 98.47 %. Linkage analysis in the RILs identified 12 quantitative traits loci (QTLs), with five of these QTLs being associated with seed size, five with seed shape and two with the two first principal components of our principal component analysis (PCA). Association analysis in the 219 accessions detected 41 single nucleotide polymorphism (SNP)-trait associations, with 20 of these SNPs being associated with seed-size traits, seven with seed-shape traits and 14 with the two first principal components of our PCA. This analysis reveals that seed-size and seed-shape may be controlled by different genetic factors. Our results provide a greater understanding of phenotypic structure and genetic architecture of soybean seed, and the QTLs detected in this study form a basis for future fine mapping, quantitative trait gene cloning and molecular breeding in soybean.

High-Performance Shortwave Infrared Detector Based on Multilayer Carbon Nanotube Films.

Carbon nanotube (CNT) is an ideal candidate material for shortwave infrared (SWIR) detectors due to its large band gap tunability, strong infrared light absorption, and high mobility. Furthermore, the photodetectors based on CNT can be prepared on any substrate using a low-temperature process, which is conducive to three-dimensional (3D) integration. However, owing to the absorption limitation (<2%) of a single-layer network CNT film with low density, the photodetectors of CNT film show low photocurrent responsivity and detectivity. In this paper, we optimize the thickness of the high-purity semiconducting network CNT films to increase the photocurrent responsivity of the photodetectors. When the thickness of network CNT film is about 5 nm, the responsivity of the zero-bias voltage can reach 32 mA/W at 1800 nm wavelength. Then, using stacked CNT films and contact electrode design, the photodetectors exhibit a maximum responsivity of 120 mA/W at 1800 nm wavelength. The photodetectors with stacked CNT films and local n-type channel doping demonstrated a wide response spectral range of 1200-2100 nm, a peak detectivity of 3.94 × 109 Jones at room temperature, and a linear dynamic range over 118 dB. Moreover, the peak detectivity is over 2.27 × 1011 Jones when the temperature is 180 K. Our work demonstrates the potential of the CNT film for future SWIR imaging at a low cost.

A new allele PEL9 GG identified by genome-wide association study increases panicle elongation length in rice (Oryza sativa L.).

Considering the male sterile line has the phenomenon of panicle enclosure, panicle elongation length (PEL) plays an important role in hybrid rice seed production. However, the molecular mechanism underlying this process is poorly understood. In this study, we investigated the PEL phenotypic values of 353 rice accessions across six environments, which shows abundant phenotypic variation. Combining the 1.3 million single-nucleotide polymorphisms, we performed a genome-wide association study on PEL. Three quantitative trait loci (QTL) qPEL4, qPEL6, and qPEL9 were identified as significantly associated with PEL, of which qPEL4 and qPEL6 were previously reported QTLs and qPEL9 was novel. One causal gene locus, PEL9, was identified and validated. The PEL of accessions carrying allele PEL9 GG was significantly longer than that of those carrying allele PEL9 TT. We also demonstrated that the outcrossing rate of female parents carrying allele PEL9 GG increased by 14.81% compared with that of the isogenic line carrying allele PEL9 TT in an F1 hybrid seed production field. The allele frequency of PEL9GG increased gradually with an increase in latitude in the Northern Hemisphere. Our results should facilitate the improvement of the PEL of the female parent of hybrid rice.

Screening germplasm and detecting QTLs for mesocotyl elongation trait in rice (Oryza sativa L.) by association mapping.

BACKGROUND: Rice is one of the most important food crops in the world and mainly cultivated in paddy field by transplanting seedlings. However, increasing water scarcity due to climate change, labor cost for transplanting, and competition from urbanization is making this traditional method of rice production unsustainable in the long term. In the present study, we mined favorable alleles for mesocotyl elongation length (MEL) by combining the phenotypic data of 543 rice accessions with genotypic data of 262 SSR markers through association mapping method. RESULTS: Among the 543 rice accessions studied, we found 130 accessions could elongate mesocotyl length under dark germination condition. A marker-trait association analysis based on a mixed linear model revealed eleven SSR markers were associated with MEL trait with p-value less than 0.01. Among the 11 association loci, seven were novel. In total, 30 favorable marker alleles for MEL were mined, and RM265-140 bp showed the highest phenotypic effect value of 1.8 cm with Yuedao46 as the carrier accession. The long MEL group of rice accessions had higher seedling emergence rate than the short MEL group in the field. The correlation coefficient (r GCC-FSC = 0.485**) between growth chamber condition (GCC) and field soil condition (FSC) showed positive relationship and highly significant (P < 0.01) indicating that the result obtained in GCC could basically represent that obtained under FSC. CONCLUSION: Not every genotype of the rice possesses the ability to elongate its mesocotyl length under dark or deep sowing condition. Mesocotyl elongation length is a quantitative trait controlled by many gene loci, and can be improved by pyramiding favorable alleles dispersed at different loci in different germplasm into a single genotype.

LAX1, functioning with MADS-box genes, determines normal palea development in rice.

Normal floral organ development in rice is necessary for grain formation. Many MADS-box family genes that belong to ABCDE model have been widely implicated in rice flower development. The LAX1 allele encodes a plant-specific basic helix-loop-helix (bHLH) transcription factor, which is the main regulator of axillary meristem formation in rice. However, the molecular mechanisms of LAX1 allele together with MADS-box family genes underlying palea development have not been reported. We found a short palea mutant plant in a population of indica rice variety 9311 treated with cobalt 60. We report the map-based cloning and characterization of lax1-7, identified as a new mutant allele of the LAX1 locus, and the role of its wild-type allele LAX1 in rice palea development. Through complementary experiments, combined with genetic and molecular biological analyses, the function of the LAX1 allele was determined. We showed that LAX1 allele is expressed specifically in young spikelets and encodes a nucleus-localized protein. In vitro and in vivo experiments revealed that the LAX1 protein physically interacts with OsMADS1, OsMADS6 and OsMADS7. The LAX1 allele is pleiotropic for the maintenance of rice palea identity via cooperation with MADS-box genes and other traits, including axillary meristem initiation, days to heading, plant height, panicle length and spikelet fertility.