Efficient Selection Tool Research Articles

Prediction of high coronary artery calcium (CAC) scores from aortic arch calcification: An efficient tool for selection of non-optimal candidates for coronary CTA?

PurposeOverutilization of healthcare resources is causing a high socioeconomic burden. Patients with high coronary artery calcium (CAC) scores > 1000AU are not optimal candidates for coronary CTA and better suited for other diagnostic strategies. Therefore, our objective was to evaluate whether a 4-scale aortic arch calcification severity (AoArCa) score from CT and X-Ray predicts high-CAC scores. MethodsPatients referred to coronary/aortic CT-Angiography were enrolled. The severity of aortic arch calcification (AoArCa) was scored as grade: 0 = absent, 1 = minimal (<25 % of circumference), 2 = mild (25–50 %), 3 = moderate (50–75 %) and 4 = severe (75–100 %) on both thoracic CT and X-ray. ResultsIn 130 patients, the absence of AoArCa by CT was highly accurate to rule out CAC > 1000AU (sens. 100 %). No or minimal AoArCa had a high NPV of 95.6 % to rule out CAC > 1000 and grade 0,1 + 2 a NPV of 86.96 %.The AUC of AoArCa by CT for predicting high CAC > 1000 was c = 0.84 (p < 0.001; 95 %CI: 0.771––0.91). For moderate-to-severe AoArCa, accuracy was c = 0.792 (p < 0.001).The intermodality agreement between CT and X-Ray based AoArCa Scores was good (r = 0.824, p < 0.001); ICC = 0.902. For X-ray, AUC was c = 0.715 to predict CAC > 1000 (p < 0.001).In regression models, only moderate-or-severe AoArCa, but not the other CVRF predicted CAC > 1000 (p < 0.001), and there was an association of the number of CVRF. ConclusionsPatients with moderate-to-severe aortic arch calcification have a high probability of CAC > 1000AU, but not those with no, minimal and mild. The absence of AoArCa rules out CAC > 1000AU. AoArCa severity may serve as valuable tool for selecting the diagnostic strategy.

Canopy coverage phenotyping and field spatial variability adjustment as an efficient selection tool in soybean breeding

AbstractAccurate estimation of grain yield potential in soybean [Glycine max (L.) Merr.] progeny rows (PRs) by measuring yield itself is challenging due to the small number of seeds available. To obtain more precise estimates of soybean yield potential and control nongenetic sources of variability, soybean breeders in the United States use secondary traits, visual selection (VIS), adjustments for field spatial variation, pedigree (PED) information, and unmanned aerial systems–based plant phenotypes; however, there are limited comparisons among the different PR testing procedures. We conducted a selection experiment in 2018 PR populations developed for yield and diversity from four soybean breeding programs. Then, we compared the performance of the lines selected using 13 selection categories in 2019 preliminary yield trials (PYTs). The sources of information used across categories included spatially adjusted (SP) traits, PED information, the canopy of the plant measured by aerial and ground digital images, reproductive length (RL), and grain yield (YLD). SP trait covariates and canopy data were the information sources most highly associated with lower yield ranks and higher yield performance of PYT. The most effective secondary trait was average canopy coverage (ACC) measured by high‐throughput phenotyping (HTP) platforms. Our selection experiment shows that ACC used as a secondary trait in combination with SP trait covariates effectively selects high‐yielding lines from non‐replicated experiments. Based on the scenarios considered in this study, it may be possible to increase the gain from selection by phenotyping secondary traits using HTP and implementing spatial variation adjustments in PR trials, which could help enhance crop productivity.

Salinity stress tolerance and omics approaches: revisiting the progress and achievements in major cereal crops.

Salinity stress adversely affects plant growth and causes considerable losses in cereal crops. Salinity stress tolerance is a complex phenomenon, imparted by the interaction of compounds involved in various biochemical and physiological processes. Conventional breeding for salt stress tolerance has had limited success. However, the availability of molecular marker-based high-density linkage maps in the last two decades boosted genomics-based quantitative trait loci (QTL) mapping and QTL-seq approaches for fine mapping important major QTL for salinity stress tolerance in rice, wheat, and maize. For example, in rice, 'Saltol' QTL was successfully introgressed for tolerance to salt stress, particularly at the seedling stage. Transcriptomics, proteomics and metabolomics also offer opportunities to decipher and understand the molecular basis of stress tolerance. The use of proteomics and metabolomics-based metabolite markers can serve as an efficient selection tool as a substitute for phenotype-based selection. This review covers the molecular mechanisms for salinity stress tolerance, recent progress in mapping and introgressing major gene/QTL (genomics), transcriptomics, proteomics, and metabolomics in major cereals, viz., rice, wheat and maize.

Genome-Wide Association Analysis for Stem Cross Section Properties, Height and Heading Date in a Collection of Spanish Durum Wheat Landraces.

Durum wheat landraces have a high potential for breeding but they remain underexploited due to several factors, including the insufficient evaluation of these plant materials and the lack of efficient selection tools for transferring target traits into elite backgrounds. In this work, we characterized 150 accessions of the Spanish durum wheat collection for stem cross section, height and heading date. Continuous variation and high heritabilities were recorded for the stem area, pith area, pith diameter, culm wall thickness, height and heading date. The accessions were genotyped with DArTSeq markers, which were aligned to the durum wheat ‘Svevo’ genome. The markers corresponding to genes, with a minor allele frequency above 5% and less than 10% of missing data, were used for genome-wide association scan analysis. Twenty-nine marker-trait associations (MTAs) were identified and compared with the positions of previously known QTLs. MTAs for height and heading date co-localized with the QTLs for these traits. In addition, all the MTAs for stem traits in chromosome 2B were located in the corresponding synteny regions of the markers associated with lodging in bread wheat. Finally, several MTAs for stem traits co-located with the QTL for wheat stem sawfly (WSS) resistance. The results presented herein reveal the same genomic regions in chromosome 2B are involved in the genetic control of stem traits and lodging tolerance in both durum and bread wheat. In addition, these results suggest the importance of stem traits for WSS resistance and the potential of these landraces as donors for lodging tolerance and WSS resistance enhancement. In this context, the MTAs for stem-related traits identified in this work can serve as a reference for further development of markers for the introgression of target traits into elite material.

Ultrassonografia testicular em touros jovens e correlação com puberdade e produção espermática

O presente trabalho tem por objetivo avaliar a ecogenicidade do parênquima testicular de touros jovens correlacionando com puberdade precoce. O estudo foi desenvolvido com 39 tourinhos puros de origem (PO) da raça Nelore, com idade entre 12 a 18 meses. A coleta foi realizada mensalmente, onde foi registrado peso, medida da circunferência escrotal e ultrassonografia testicular. A coleta do sêmen foi realizada apenas em animais nas faixas etárias de 14, 16 e 18 meses. Os dados coletados foram organizados em planilha do programa Microsoft Office Excel 2010, para posterior analise utilizando-se o programa estatístico Minitab. Os animais foram separados em dois grupos, os que produziram sêmen e os que não produziram e então classificados em precoces, super-precoces e normais, as médias geradas pela anova foram comparadas pelo teste de Tukey. As variáveis foram correlacionadas pelo método de Pearson. A ecogenicidade do parênquima testicular não influenciou na produção espermática e na precocidade. Os animais precoces apresentaram peso e CE superior aos super-precoces e normais. Peso e idade apresentaram alta correlação, não houve correlação entre peso e média da escala de cinza e, circunferência escrotal e média da escala de cinza. Touros com 18 meses apresentaram percentual de defeitos total inferior a 30%. realização da ultrassonografia testicular não é adequada como indicador de precocidade sexual e produção espermática. A aferição do peso corporal e circunferência escrotal são ferramentas mais eficazes para predizer o potencial reprodutivo de touros Nelore (PO) jovens, sendo estas também, ferramentas de seleção economicamente mais eficientes.

Monitoring the transition from endodormancy to ecodormancy in almond through the analysis and expression of a specific class III peroxidase gene

For fruit tree species, bud endodormancy is a crucial step, as its progression over winter determines the quality of blooming and the flowering time. Understanding the relationship between endodormancy, ecodormancy, and flowering processes is thus a fundamental goal in molecular biology studies of these species mainly in the present climate change and warming context. Knowing the molecular basis of the control of endodormancy and flowering will allow us to develop efficient selection tools like molecular markers for monitoring the process. In this 2-year study, to understand the transcriptional changes leading to the endodormancy release of flower buds, we cloned a candidate transcript and analysed its expression by qPCR in the flower buds of three almond (Prunus dulcis (Miller) Webb) cultivars with different endodormancy period lengths and flowering times. The candidate transcript, named PdP40, has been described as a member of the flower-specific class III peroxidase family. Expression results highlight a significant increase in the transcript levels of this gene before endodormancy release in the three cultivars assayed, independent of the endodormancy period. Furthermore, total peroxidase activity was analysed in flower bud samples. Results suggest an important role for this peroxidase in this process and the possibility of using it as an expression marker for predicting endodormancy release in the field.

Nanostructured Semiconducting Metal Oxides for Ammonia Sensors. A Novel HSAB Sensing Paradigm

The paper demonstrates how the Hard-Soft Acid Base (HSAB) theory can be used as a valuable criterion in the selection process of semiconducting metal oxides (MOX) suitable as sensing layers for ammonia detection. Six different cases of ammonia detection performed by chemiresistive sensors employing MOX and related nanocomposites as sensing layers are identified and discussed. The role of HSAB as an efficient selection tool for appropriate sensing layer (any type of gas), is further reinforced by analyzing and discussing literature results on MOX-based trimethylamine sensing layers. By analyzing the operation of a fiber-optic ammonia sensor, we demonstrate that the HSAB principle can be also successfully applied to the selection of sensing layers for detectors employing other sensing principles, different than the chemiresistive one. Changing the sensing paradigm (i.e., the amino groups-based compounds are part of the sensing layer, rather than part of the analyte), the paper shows that these types of molecules (polymers, carbon nanotubes, ionic liquids) are appropriate constituents of a CO2 sensing layer, in full accordance to the HSAB criteria.

Gene expression analysis of related dormancy genes during bud dormancy progression in field conditions in almond

Flowering time is a trait of great interest in almond breeding. Knowing the molecular basis underlying this trait would allow the development of efficient selection tools for almond breeding. Almond flowering comes in response to a pattern of low temperatures (for bud dormancy breaking) and high temperatures (after bud dormancy breaking). These chill and heat requirements ensure that flowering will take place under suitable conditions for pollination in each growing zone. In order to identify the genome regions involved in flowering time and dormancy regulation, four genes including genes related to transcription regulation and phytohormone signaling were analyzed by qPCR. These assays were performed in flower buds of two almond cultivars including 'Desmayo Largueta' (extra-early flowering) and 'Penta' (extra-late flowering), during bud dormancy progression. Results suggested that the expression of PdDREB2c, PdAFP and PdGA2ox was notably reduced at the moment of bud dormancy breaking, highlighting the role of these genes in maintaining bud dormancy and thus determine the flowering time. However, expression of PdPIE1 largely increased close to the moment of bud dormancy breaking, which could indicate the involvement of an epigenetic regulator to control this process.

Molecular cloning and expression of PdP40, a flower specific class III peroxidase gene in almond

A fundamental issue of plant molecular biology is to understand the relationship between dormancy and flowering processes, but it is also of practical interest in agriculture and breeding. Knowing the molecular basis of the control of flowering allows us to develop efficient selection tools, as molecular markers. To investigate the genes involved in the dormancy breaking of flower buds, a candidate transcript was cloned and its expression was analysed by qPCR in flower buds of two almond (Prunus dulcis) cultivars including ‘Desmayo Largueta’ (extra-early flowering) and ‘Penta’ (extra-late flowering). The candidate transcript has been described as a PEROXIDASE 40 gene from a flower specific Class III peroxidase family. The full-length cDNA clone, designated PdP40, was isolated using 3’-RACE strategy with primers from peach (Prunus persica) sequences. Expression results highlight an important increase of transcript levels of this gene before breaking dormancy, in both extra-early and extra-late flowering cultivars assayed. This suggests the important role of this kind of peroxidases in this process, and the possibility to use them as expression markers for predicting dormancy release in the field.

Bacterial Genome Editing with CRISPR-Cas9: Taking Clostridium beijerinckii as an Example.

CRISPR-Cas9 has been explored as a transformative genome engineering tool for many eukaryotic organisms. However, its utilization in bacteria remains limited and ineffective. This chapter, taking Clostridium beijerinckii as an example, describes the use of Streptococcus pyogenes CRISPR-Cas9 system guided by the single chimeric guide RNA (gRNA) for diverse genome-editing purposes, including chromosomal gene deletion, integration, single nucleotide modification, as well as "clean" mutant selection. The general principle is to use CRISPR-Cas9 as an efficient selection tool for the edited mutant (whose CRISPR-Cas9 target site has been disrupted through a homologous recombination event and thus can survive selection) against? the wild type background cells. This protocol is broadly applicable to other microorganisms for genome-editing purposes.

Molecular characterisation in tomato (solanum lycopersicumL.) - A review

Tomato (Solanum lycopersicum L.) is most important fruit vegetable grown worldwide for its high nutritive value. Traditional genetic markers and breeding methods have several defects that reduce the ability to estimate genetic diversity in plants as it highly dependent on the environment for expression. Among the available genetic rnarkers viz., morphological, cytological, biochemical and molecular (DNA), Molecular markers are an effective tool for efficient selection of desired agronomic traits because they are based on the plant genotypes and also are independent of environmental variations. Researchers have been calculated genetic variation in tomato landrace and cultivar collections using several molecular techniques including AFLP, RAPD, ISSR, SSR and SNP. An overview is conducted considering some useful above mentioned molecular markers to initiate systematic breeding programme on tomato improvement.

Evolution of 2014/15 H3N2 Influenza Viruses Circulating in US: Consequences for Vaccine Effectiveness and Possible New Pandemic.

A key factor in the effectiveness of the seasonal influenza vaccine is its immunological compatibility with the circulating viruses during the season. Here we propose a new bioinformatics approach for analysis of influenza viruses which could be used as an efficient tool for selection of vaccine viruses, assessment of the effectiveness of seasonal influenza vaccines, and prediction of the epidemic/pandemic potential of novel influenza viruses.

양친의 대량 염기서열 해독을 통해 개발된 SNP 분자표지를 이용한 고추 유전자지도 작성

Molecular markers, as an efficient selection tool, have been and is being used for practical breeding program in chili pepper (Capsicum annuum L.). Recently, a lot of researches on inheritance and genetic analysis for quantitative traits including capsaicinoids, carotenoids, and sugar content in pepper are being performed worldwide. It has been also reported that QTL mapping is a necessary tool to develop molecular markers associated with the quantitative traits. In this study, we suggested a new method to construct a pepper genetic map using SNP (HRM) markers generated from NGS resequencing of female and male parents. Plant materials were C. annuum 'NB1' (female parent), C. chinense 'Jolokia' (male parent), and their F2 population consisting of 94 progenies. Sequences of 4.6 Gbp and 6.2 Gbp were obtained from NGS resequencing of 'NB1' and 'Jolokia', respectively. Totally, 4.29 million SNPs between 'NB1' and 'Jolokia' were detected and the 1.76 million SNPs were clearly identified. Among them, total 145 SNP (HRM) primer pairs covering pepper genetic map were selected, and the 116 SNP (HRM) markers of them were located on this map. Total distance of the map, which consisted of 12 linkage groups and matched with basic chromosome numbers of pepper, was 1,167.9 cM. According to the mapping result, we concluded that our mapping method was suitable to construct a pepper genetic map fast and accurately. In addition, the genetic map could be directly used for QTL analysis of traits different between both parents.

Short communication: Estimation of genetic parameters for residual feed intake and feeding behavior traits in dairy heifers

Data from a 2-yr feeding trial of Holstein-Friesian heifers (n=842) were used to examine the heritability of feeding behavior traits and their relationships with residual feed intake (RFI), a measure of feed efficiency. Five traits were assessed: number of meals, feeding duration, dry matter intake (DMI), eating rate, and average meal size. For estimating genetic parameters, all traits were simultaneously fitted in a multivariate model with a genomic relationship matrix calculated from heifers’ high-density genotype data. All 5 traits were moderately heritable (0.45–0.50), which was slightly higher than the estimate for RFI (0.40±0.09). Two traits had modest genetic correlations with RFI (DMI and feeding duration; 0.45±0.13 and 0.27±0.15, respectively), and 2 traits had modest phenotypic correlations with RFI (DMI and eating rate; 0.52±0.03 and 0.23±0.04, respectively). The results indicate that feeding behavior (1) may differ between efficient and inefficient animals and (2) may be useful for selecting animals with better feed efficiency. However, the limitation is that measurements on DMI are still essential. It is therefore possible that a more efficient selection tool for RFI may be the use of high-density DNA markers to make direct genomic predictions for RFI.

Crop breeding for salt tolerance in the era of molecular markers and marker‐assisted selection

AbstractCrop salt tolerance (ST) is a complex trait affected by numerous genetic and non‐genetic factors, and its improvement via conventional breeding has been slow. Recent advancements in biotechnology have led to the development of more efficient selection tools to substitute phenotype‐based selection systems. Molecular markers associated with genes or quantitative trait loci (QTLs) affecting important traits are identified, which could be used as indirect selection criteria to improve breeding efficiency via marker‐assisted selection (MAS). While the use of MAS for manipulating simple traits has been streamlined in many plant breeding programmes, MAS for improving complex traits seems to be at infancy stage. Numerous QTLs have been reported for ST in different crop species; however, few commercial cultivars or breeding lines with improved ST have been developed via MAS. We review genes and QTLs identified with positive effects on ST in different plant species and discuss the prospects for developing crop ST via MAS. With the current advances in marker technology and a better handling of genotype by environment interaction effects, the utility of MAS for breeding for ST will gain momentum.

Development of DNA markers associated with beer foam stability for barley breeding

Traits conferring brewing quality are important objectives in malting barley breeding. Beer foam stability is one of the more difficult traits to evaluate due to the requirement for a relatively large amount of grain to be malted and then the experimental costs for subsequent brewing trials. Consequently, foam stability tends to be evaluated with only advanced lines in the final stages of the breeding process. To simplify the evaluation and selection for this trait, efficient DNA makers were developed in this study. Previous studies have suggested that the level of both of the foam-associated proteins Z4 and Z7 were possible factors that influenced beer foam stability. To confirm the relationship between levels of these proteins in beer and foam stability, 24 beer samples prepared from malt made from 10 barley cultivars, were examined. Regression analyses suggested that beer proteins Z4 and Z7 could be positive and negative markers for beer foam stability, respectively. To develop DNA markers associated with contents of proteins Z4 and Z7 in barley grain, nucleotide sequence polymorphisms in barley cultivars in the upstream region of the translation initiation codon, where the promoter region might be located were compared. As a result, 5 and 23 nucleotide sequence polymorphisms were detected in protein Z4 and protein Z7, respectively. By using these polymorphisms, cleaved amplified polymorphic sequence (CAPS) markers were developed. The CAPS markers for proteins Z4 and Z7 were applied to classify the barley grain content of 23 barley cultivars into two protein Z4 (pZ4-H and pZ4-L) and three protein Z7 (the pZ7-H, pZ7-L and pZ7-L2) haplotypes, respectively. Barley cultivars with pZ4-H showed significantly higher levels of protein Z4 in grain, and those with pZ7-L and pZ7-L2 showed significantly lower levels of protein Z7 in grain. Beer foam stability in the cultivars with pZ4-H and pZ7-L was significantly higher than that with pZ4-L and pZ7-H, respectively. Our results indicate that these CAPS markers provide an efficient selection tool for beer foam stability in barley breeding programs.

A Novel Vector for Positive Selection of Inserts Harboring an Open Reading Frame by Translational Coupling

We have developed a novel vector pTCS, as a tool for efficient selection of open reading frame (ORF)-containing inserts. In pTCS clones containing an insert with an ORF a downstream marker gene (immE3, conferring resistance to colicin) is activated via translational coupling with the insert, and transformed cells can then be selected by exposure to colicin E3. Our method differs from previous methods in that the marker gene is activated without protein fusion, and that selection occurs irrespective of the reading frame of the insert.

Effectiveness of Environmental Cluster Analysis in Representing Regional Species Diversity

A major challenge of regional conservation planning is the identification of sets of sites that together represent the overall biodiversity of the relevant region. Environmental cluster analysis (ECA) has been proposed as a potential tool for efficient selection of conservation sites, but the consequences of methodological decisions involved in its application have not been tested so far. We evaluated the performance of ECA with respect to two such decisions: the choice of the clustering algorithm (single linkage, complete linkage, unweighted arithmetic average, unweighted centroid, Ward's minimum variance, and the ALOC algorithm) and the weight given to different groups of environmental variables (rainfall, temperature, and lithology). Specifically we tested how these decisions affect the spatial configuration of clusters of sites defined by the ECA, whether and how they affect the effectiveness of the ECA (i.e., its ability to represent regional species diversity), and whether the effectiveness of alternative methods of hierarchical clustering can be predicted a priori based on the cophenetic correlation. We used an extensive database of the flora of Israel to test these questions. Differences in both the clustering algorithm and the weighting regime had considerable effects on the spatial configuration of the ECA clusters. The single-linkage algorithm produced mostly single-cell clusters plus a single large-sized cluster and was therefore found inappropriate for environmental regionalization. The effectiveness of the ECA was also sensitive to changes in the clustering algorithm and the weighting regime. Yet, most combinations of clustering algorithms and weighting regimes performed significantly better in capturing regional biodiversity than random null models. The main deviation was classifications based on Ward's minimum variance algorithm, which performed less well relative to all other algorithms. The two algorithms that showed the highest effectiveness (unweighted average and unweighted centroid clustering) also exhibited the highest values of the cophenetic correlation, suggesting that this index may serve as a potential indicator for the effectiveness of alternative ECA algorithms.

Chlorophyll fluorescence as a selection tool for cold tolerance of photosynthesis in maize (Zea mays L.)

The possibility of using quenching analysis of chlorophyll a fluorescence as a selection tool for improving the cold tolerance of maize was investigated in six genotypes differing greatly in the ability to develop a competent photosynthetic apparatus at low temperature. Upon gradual cooling, measurements of the quantum yield of electron transport (Φ PSII ) indicated that leaves of tolerant genotypes, that developed at suboptimal temperature (15°C), maintained higher rates of electron transport than leaves of sensitive genotypes. This difference was largely due to the ability of the tolerant plants to keep higher efficiency of excitation energy capture by open photosystem II reaction centres (F' v /F' m ). The absence of genotypic differences in leaves that developed at optimal temperature indicates that the trait is not expressed constitutively, but relies on adaptation mechanisms. Furthermore, the genotypic difference was not expressed under increasing illumination at 15°C and 25°C suggesting that the trait is also low-temperature-specific and is not expressed solely in response to increasing excess light energy. Applying the method to flint and dent breeding population led to a substantial increase (up to 31%) in the photosynthetic capacity of hybrids between selected F 3 inbreeding families grown at suboptimal temperature, demonstrating that the method is an efficient selection tool for improving the cold tolerance of maize through breeding.

Rice crop duration and leaf appearance rate in a variable thermal environment. II. Comparison of genotypes

Rice crop duration in tropical-arid, irrigated environments, such as the Sahel, varies strongly among seasons and years. For rice double-cropping systems, cultivars are needed that have a stable duration under variable daylengths and temperatures. No efficient selection tools are currently available to screen for comparatively thermo- and photoperiod-insensitive cultivars, and little is known about the genetic diversity of rice in this respect. A previous study presented a model that disaggregates photothermal effects on rice phenology for the different crop development stages and the two main factors, daylength and temperature. The present study characterizes differences in the photothermal response of 18 rice lines for three major phases of their development, namely, germination, the appearance of early leaves, and the induction phase (IP) between the end of the basic vegetative phase (BVP) and panicle initiation (PI). A field experiment was conducted at Ndiaye in Senegal, using 11 staggered sowing dates at 15 day intervals. Three check cultivars were replicated four times per date, and the others were not replicated. Phenological observations included leaf tip appearance rates on a daily basis, and heading and flowering dates. Water and air temperatures were also monitored. The duration from seed soaking to the appearance of the first leaf depended linearly on water temperature, with a base temperature of about 8°C. No differences were observed among lines. The appearance rate of the first to the fourth leaf had an optimum temperature ( T opt) between 22°C and 25°C, with significant differences between lines. Lines with low T opt had high maximal leaf appearance rates during seedling stage. The quantitatively most important component of the seasonal variability of crop duration was IP, which depended on temperature and photoperiod. Photoperiodic and temperature effects were disaggregated using an empirically based model leaf appearance (LAP), which, by way of parametrization, helped quantify genotypic differences. The photothermal differences between lines were associated with adaptation to specific seasons. Lines such as IR13240-108-2-2-3, which is adapted to several seasons, were comparatively insensitive to photoperiod and temperature. That line also had a low T opt and a high Leaf Appearance. In conclusion, screening for temperature-insensitive leaf appearance rates may be promising for rice breeding for arid, irrigated environments. Selection for combined low thermal and photoperiod sensitivity, however, would be impractical on an experimental basis, and would therefore require genetic markers.