Heat Tolerance Traits Research Articles

Role of integrated crop-livestock system on amelioration of heat stress on crossbred Brazilian sheep in semiarid region of northeastern Brazil

• Physiological parameters were lower in the animals under ICL system. • ICL did not promote heat stress in the morning. • The presence of trees in the ICL system promoted thermal comfort to the animals. • Greater sheep ability to dissipate the heat under ICL. • Sustainable sheep production. The aim of this study was to evaluate the effect of livestock rearing system, sheepfold vs . integrated crop-livestock system, on heat tolerance and physiological traits of crossbred sheep (Santa Ines x Dorper) in the semiarid region of Brazilian Northeastern. Forty crossbred hair ewes (Santa Ines x Dorper), 15–48 months old, were assigned to two treatments: 20 in treatment I (SF – Sheepfold) and 20 in treatment II (ICL - integrated crop-livestock system with tall coconut palm trees). Physiological and environmental evaluations were conducted on 21 consecutive days. Respiratory rate (RR), rectal temperature (RT) and heart rate (HR) were recorded at 06:00 am and 05:00 pm, while air temperature and relative humidity were recorded from 06:00 am to 05:00 pm. Temperature and Humidity Index (THI) in the SF and ILC indicated severe stress for sheep regardless of the period of the day, and although THI in integrated crop-livestock system was 1% lower than in the sheepfold, there was no statistical differences between the treatments. Ewes from integrated crop-livestock system had lower RR and HR than sheepfold ewes at 06:00 am and 05:00 pm. The afternoon period led the animals to more dangerous situation of thermal stress condition in both treatments, however we suggest that the presence of trees in the ICL system promoted an amelioration of heat stress on grazing ewes.

Molecular characterization and identification of SNPs in ATP1A1 isoform of sodium-phosphate adenosine triphosphatase across diverse breeds of riverine buffaloes (Bubalus bubalis) and Indian native cattle (Bos indicus): A plausible candidate gene for heat tolerance

In the present study, efforts were made to sequence characterize the selected exonic region (18–21) of ATP1A1 gene to identify variations/SNPs in different breeds of Indian riverine buffaloes and native cattle. The sequence characterization of selected intronic/exonic region (17–21) of ATP1A1 gene was carried out in a total of 120 samples which included 6 animals each of 8 buffalo breeds and 72 animals of 12 cattle breeds. Genomic DNA was extracted from the whole blood by enzymatic digestion using proteinase K using phenol:chloroform method.. Three sets of primers were designed using Primer3 software to amplify genomic region from intron 17 to intron 21 of ATP1A1 gene in both cattle and buffaloes. The amplified products were purified by enzymatic method and purified PCR products were sequenced using forward primers in an ABI 3100 Automated DNA Sequencer. The chromatogram of each sequence obtained was checked manually. Base calling was performed with Phred and contig assembly was done via Phrap/Cross_match/Swat tool available in the suite Codon code Aligner v. 3.5.1. The results revealed a total of 26 variations in exons 18–21 of ATP1A1 gene in riverine buffalo. Out of 26 variations, 6 (T27006876C, C27006599T, T27006345C, T27006330C, G27006309T and T27006240C) were distributed across 4 exonic regions and the remaining 20 were located in intronic region whereas in native cattle, only 2 SNPs were identified in exonic regions (18–21). SNP T27007767C was found to be a novel one in 18 intronic region of ATP1A1 gene in Indian cattle breeds. All 7 variations found in exonic region of both buffalo and cattle breeds were synonymous with the predicted changes in amino acids. The variations identified in ATP1A1 gene in the present study could be evaluated in future for their roles in heat tolerance trait in riverine buffaloes and native cattle.

Can Swiss wheat varieties escape future heat stress?

Climate change-induced heat waves represent a severe threat to future global crop production. The extent of heat stress for agricultural crops depends on the co-occurrence of heat periods and heat sensitive phenological stages. Using the Wang and Engel phenology model and the most recent climate change projections for four sites across the Swiss Central Plateau, we estimated future heat stress exposure in Swiss wheat production and tested the potential of winter wheat genotypes with differing phenological characteristics to escape future heat periods. Across all genotypes, heat stress days (Tmax ≥ 30 °C) during the temperature sensitive stages of flowering and early grain filling increased from an average of 1.5 heat days in 1982−2006 to 2.1 by 2075−2099 with RCP2.6 (with climate change mitigation) and to 3.6 by 2075−2099 with RCP8.5 (without climate change mitigation), respectively. Across all genotypes and locations, a considerable escape from future heat periods was modelled due to a mainly temperature-driven advancement in the phenological development. Under both RCP scenarios, we predicted lower exposure to heat stress for early varieties than for late varieties. However, under the RCP8.5 scenario, for each location, heat stress exposure for early varieties was still projected to be higher by 2075−2099 than for late varieties under current conditions. Further, heat stress exposure was considerably increased at locations with cooler spring conditions, slowing down the early season phenological development and resulting in late heading dates. Our findings imply needs for a regionally adequate cultivar selection as well as for phenological adaptions and heat tolerance traits in Swiss wheat breeding to adapt to future climate change and regional climatic differences. Different strategies of breeding adaptations and their trade-offs are discussed.

Efficient Regulation of CO2 Assimilation Enables Greater Resilience to High Temperature and Drought in Maize.

Increasing temperatures and extended drought episodes are among the major constraints affecting food production. Maize has a relatively high temperature optimum for photosynthesis compared to C3 crops, however, the response of this important C4 crop to the combination of heat and drought stress is poorly understood. Here, we hypothesized that resilience to high temperature combined with water deficit (WD) would require efficient regulation of the photosynthetic traits of maize, including the C4–CO2 concentrating mechanism (CCM). Two genotypes of maize with contrasting levels of drought and heat tolerance, B73 and P0023, were acclimatized at high temperature (38°C versus 25°C) under well-watered (WW) or WD conditions. The photosynthetic performance was evaluated by gas exchange and chlorophyll a fluorescence, and in vitro activities of key enzymes for carboxylation (phosphoenolpyruvate carboxylase), decarboxylation (NADP-malic enzyme), and carbon fixation (Rubisco). Both genotypes successfully acclimatized to the high temperature, although with different mechanisms: while B73 maintained the photosynthetic rates by increasing stomatal conductance (gs), P0023 maintained gs and showed limited transpiration. When WD was experienced in combination with high temperatures, limited transpiration allowed water-savings and acted as a drought stress avoidance mechanism. The photosynthetic efficiency in P0023 was sustained by higher phosphorylated PEPC and electron transport rate (ETR) near vascular tissues, supplying chemical energy for an effective CCM. These results suggest that the key traits for drought and heat tolerance in maize are limited transpiration rate, allied with a synchronized regulation of the carbon assimilation metabolism. These findings can be exploited in future breeding efforts aimed at improving maize resilience to climate change.

Factors determining the occurrence of floret sterility in rice in a hot and low-wind paddy field in Jianghan Basin, China

• High temperature (<36.5 °C) and low wind induced floret sterility in the paddy field. • High temperatures increased the sterility through processes after pollen germination. • Wind lessened the sterility through stable pollination and probably via cooling. • Positive effects of low and erect panicle, and short anther were newly demonstrated. • Positive effects of long basal anther dehiscence and early flowering were confirmed. Global warming may increase the occurrence of heat-induced floret sterility (HIFS) in rice. The effects of meteorological factors and plant traits on the occurrence of floret sterility have only been examined independently and under controlled or simplified conditions. The aim of this study was to comprehensively clarify the role and impact of these factors in HIFS in rice under practical field conditions. We observed pollination and seed set of 12 rice cultivars with wide variation in traits potentially related to HIFS for 3 years in a paddy field in the Yangtze Valley in China where HIFS sometimes occurs. Floret sterility increased as temperature increased under moderately high temperatures (32–36.5 °C) and low-wind conditions (<3.5 m s −1 at flowering time). Path analysis with multiple regression revealed that high temperatures increased the occurrence of floret sterility through processes after pollen germination on the stigma and that wind lessened the occurrence of floret sterility; the magnitude of the wind effect was equivalent to that of high temperature. Multiple regression analysis estimated that low and erect panicles, and short anthers have positive effects on tolerance to HIFS and known heat tolerance traits, e.g., long anther dehiscence at the base of the anther and early morning flowering. The results clarified the factors that control HIFS in the paddy field and identify the processes and traits that scientists and breeders should focus on to mitigate HIFS under global warming.

Physiological and genetic characterization of heat stress effects in a common bean RIL population.

Heat stress is a major abiotic stress factor reducing crop productivity and climate change models predict increasing temperatures in many production regions. Common bean (Phaseolus vulgaris L.) is an important crop for food security in the tropics and heat stress is expected to cause increasing yield losses. To study physiological responses and to characterize the genetics of heat stress tolerance, we evaluated the recombinant inbred line (RIL) population IJR (Indeterminate Jamaica Red) x AFR298 of the Andean gene pool. Heat stress (HS) conditions in the field affected many traits across the reproductive phase. High nighttime temperatures appeared to have larger effects than maximum daytime temperatures. Yield was reduced compared to non-stress conditions by 37% and 26% in 2016 and 2017 seasons, respectively. The image analysis tool HYRBEAN was developed to evaluate pollen viability (PolVia). A significant reduction of PolVia was observed in HS and higher viability was correlated with yield only under stress conditions. In susceptible lines the reproductive phase was extended and defects in the initiation of seed, seed fill and seed formation were identified reducing grain quality. Higher yields under HS were correlated with early flowering, high pollen viability and effective seed filling. Quantitative trait loci (QTL) analysis revealed a QTL for both pod harvest index and PolVia on chromosome Pv05, for which the more heat tolerant parent IJR contributed the positive allele. Also, on chromosome Pv08 a QTL from IJR improved PolVia and the yield component pods per plant. HS affected several traits during the whole reproductive development, from floral induction to grain quality traits, indicating a general heat perception affecting many reproductive processes. Identification of tolerant germplasm, indicator traits for heat tolerance and molecular tools will help to breed heat tolerant varieties to face future climate change effects.

Does geographic variation in thermal tolerance in Daphnia represent trade-offs or conditional neutrality?

Geographic variation in thermal tolerance in Daphnia seems to represent genetic load at the loci specifically responsible for heat tolerance resulting from conditional neutrality. We see no evidence of trade-offs between fitness-related traits at 25°C vs. 10 °C or between two algal diets across Daphnia magna clones from a variety of locations representing the opposite ends of the distribution of long-term heat tolerance. Likewise, we found no evidence of within-environment trade-offs between heat tolerance and fitness-related traits in any of the environments. Neither short-term and long-term heat tolerance shows any consistent relationship with lipid fluorescence polarization and lipid peroxidation across clones or environments. Pervasive positive correlations between fitness-related traits indicate differences in genetic load rather than trade-off based local adaptation or thermal specialization. For heat tolerance such differences may be caused by either relaxation of stabilizing selection due to lower exposure to high temperature extremes, i.e., conditional neutrality, or by small effective population size followed by the recent range expansion.

Genomic and Phenotypic Diversity of Cultivated and Wild Tomatoes with Varying Levels of Heat Tolerance.

Assessment of genetic variability in heat-tolerant tomato germplasm is a pre-requisite to improve yield and fruit quality under heat stress. We assessed the population structure and diversity in a panel of three Solanum pimpinellifolium (wild tomatoes) and 42 S. lycopersicum (cultivated tomatoes) lines and accessions with varying heat tolerance levels. The DArTseq marker was used for the sequencing and 5270 informative single nucleotide polymorphism (SNP) markers were retained for the genomic analysis. The germplasm was evaluated under two heat stress environments for five yield and flower related traits. The phenotypic evaluation revealed moderate broad-sense heritabilities for fruit weight per plant and high broad-sense heritabilities for fruit weight, number of inflorescences per plant, and number of flowers per inflorescence. The hierarchical clustering based on identity by state dissimilarity matrix and UPGMA grouped the germplasm into three clusters. The cluster analysis based on heat-tolerance traits separated the germplasm collection into five clusters. The correlation between the phenotypic and genomic-based distance matrices was low (r = 0.2, p < 0.05). The joint phenotypic and genomic-based clustering grouped the germplasm collection into five clusters well defined for their response to heat stress ranging from highly sensitive to highly tolerant groups. The heat-sensitive and heat-tolerant clusters of S. lycopersicum lines were differentiated by a specific pattern of minor allele frequency distribution on chromosome 11. The joint phenotypic and genomic analysis revealed important diversity within the germplasm collection. This study provides the basis for efficient selection of parental lines to breed heat-tolerant varieties.

Genetic polymorphism in HSPB6 gene and their association with heat tolerance traits in Indian Karan Fries (Bos taurus x Bos indicus) cattle

Heat shock proteins (HSPs) act as a chaperone activity ensuring the folding, unfolding, and refolding of denatured proteins, which help in a protective role during thermal stress in dairy cattle. This study aimed to detect genetic variations of the HSPB6 gene and to determine their association with heat tolerance traits in Karan Fries cattle. Five single nucleotide polymorphisms (SNPs) (SNP 1–5) were reported in the Karan Fries cattle, which included three transitions viz. SNP1-g.161G > A, SNP2-g.436G > A, and SNP4-g.2152A > G and two transversions viz. SNP3-g.1743C > G, SNP5-g.2417A > T. The association analysis revealed that the three SNPs loci i.e., SNP1-g.161G > A, SNP2-g.436G > A, and SNP3-g.1743C > G were significantly (p < 0.01) associated with the respiration rate (RR) and rectal temperature (RT) (°C) traits. Furthermore, in the case of heat tolerance coefficient (HTC) trait was found significantly associated (p < 0.01) with SNPs loci i.e., SNP1-g.161G > A, SNP2-g.436G > A, and SNP3-g.1743C > G. The Hap 4 (GACAT) was found to more adaptable than cattle of other haplotypes as reflected by lower values of RR, RT and HTC. This study provides the first association analyses between the SNPs and haplotypes of HSPB6 gene and heat tolerance traits in Karan Fries cattle, which could be used as effective SNP markers in genetic selection for heat tolerance in cattle breeding program.

Desiccation and temperature resistance of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae): pedestals for invasion success?

AbstractThe larger grain borer, Prostephanus truncatus (Horn) is an invasive insect pest species of global economic concern. It however remains unknown how P. truncatus succeeds under increasing temperatures and desiccation effects associated with projected climate change. Here, we investigated the effects of desiccation and high‐temperature stress on physiological fitness of P. truncatus larvae and adults. Specifically, we measured critical thermal maxima, heat knockdown time and water loss rates following heat and desiccation acclimation. Results showed beneficial heat acclimation effects on heat tolerance (critical thermal maxima and heat knockdown time). Similarly, desiccation acclimation significantly improved both heat tolerance traits, indicating cross‐tolerance effects, not for heat knockdown time in larvae. In all cases, adults exhibited more improved heat tolerance than larvae. Conversely, heat acclimation increased water loss rates, and more so in larvae than adults. Improved heat tolerance plus abiotic stress cross‐tolerance of P. truncatus may explain its enhanced physiological and ecological fitness in dry tropical and changing climate environments. These results are important in explaining the role of physiology in insect invasions and may inform pest management and forecasting.

Response of Tomato Genotypes under Different High Temperatures in Field and Greenhouse Conditions.

Heat stress is one of the production constraints for tomato (Solanum lycopersicum L.) due to unfavorable, above optimum temperatures. This research was undertaken to evaluate growth and fruit yield of tomato genotypes under three contrasting growing conditions (i.e., optimal temperature in field-, high temperature in field- and high temperature in greenhouse conditions) to determine their relative heat tolerance. Eleven tomato genotypes, including two local check varieties, were evaluated, and data on growth and yield were measured and analyzed. The interactions between the genotypes and growing conditions for all yield traits were significant. In general, the performance of tomato under optimal temperature field conditions was better than under high temperature field- and greenhouse conditions. Genotypes CLN1621L, CLN2026D, CLN3212C, and KK1 had consistently greater fruit yield per plant in all growing conditions. Although the local genotype, Neang Tamm, had lower yield under optimal conditions, it performed moderately well under high temperature field- and high temperature greenhouse conditions, and yield decrease under high temperature condition was minimal. Genotype CLN1621L had stable fruit setting compared to other genotypes under high temperature conditions. Since fruit setting and yield are important traits for heat tolerance, genotypes CLN1621L and Neang Tamm are potential candidates for breeding programs focused on improved yield and heat stress tolerance.

Identification of new sources of heat tolerance in cultivated and wild tomatoes

Heat stress adversely affects tomato production worldwide. Breeding thermotolerant varieties is critical to adapt to increased heat stress but tomato has a narrow genetic base for heat tolerance. Identification of new sources of heat-tolerant germplasm is important to understand physiological and molecular mechanisms of adaptation to heat stress and to broaden the genetic base of heat tolerance in tomato. Here, we screened a germplasm collection comprised of 42 tomato entries using 19 quantitative (physiological, reproductive, and morphological) and five qualitative traits. The plants were grown under long term mild heat stress with temperatures and relative humidities ranging from 23.3 to 37 °C, and 47 to 100%, respectively. The analysis of variance revealed significant differences among the entries for all the quantitative traits. Biologically significant associations were recorded for many traits. Proportion of viable pollen was not associated with fruit set percentage. The clustering analysis groups the germplasm into five clusters with a clear distinction between Solanum lycopersicum and Solanum pimpinellifolium entries. We also observed differences between the entries based on their origins. Known thermo-tolerant entries were found in Clusters 3 (eg.: LA2662, LA3317, LA3120) and 4 (e.g.: CL5915-93D4-1-0, CLN1621L, LA2661). Lines BJ01, BJ02 from Republic of Benin, and WAC1 and ATS020 from Ghana in Cluster 3 are potential new sources of thermo-tolerance in tomato. Generation of hybrids from parents belonging to the clusters 1 to 4 identified in this study would improve heterosis for heat tolerance traits in tomato. Useful traits like high pollen viability and high inflorescence numbers per plant could be introgressed from S. pimpinellifolium entries into the cultivated tomato. Our study provides important information to improve heat tolerance in tomato.

Morphological characterization and evaluation of heat tolerance traits in Nigerian goat breeds

There are three main breeds of goat in Nigeria: The West African Dwarf (WAD), the Red Sokoto and the Sahel. Goats are renowned for their hardiness and can survive in most environments. The goats sampling was carried out from farms and markets across different states in Nigeria, according to the geographical distribution of the breeds published by Blench (1999). This experiment was carried out to analyse morphological variability among Nigerian goats. A total of 318 goats spread across the three Nigerian breeds were used in the following populations (57 Sahel, 187 Red Sokoto and 137 West African Dwarf). Data were collected on body weight, linear body measurements and heat tolerance traits and were subjected to analysis of variance using the fixed effects of breed, sex and location. Results showed that breed, sex and location significantly (P&lt;0.05) affected all the linear body measurements and heat tolerance traits. The Sahel breed had the highest values in most of the measured traits compared to the West African Dwarf and the Red Sokoto breeds of goat. It was observed that goats from the northern part of Nigeria were heavier than their southern counterparts, and this can be likened to their genetic makeup and the extent of its interaction with the environment. The results of the study confirmed the population structure of Nigerian goat breeds and showed that they possess enough diversity to enhance genetic improvement for higher survival and productivity.

Comparative Response of Seedlings of Heat Tolerant and Sensitive Maize Genotypesregarding Early Growth Traits against Heat Stress

Comparative Response of Seedlings of Heat Tolerant and Sensitive Maize Genotypesregarding Early Growth Traits against Heat Stress

Expression of seed storage proteins responsible for maintaining kernel traits and wheat flour quality in common wheat under heat stress conditions.

Heat stress during grain filling has been documented to decrease wheat grain yield and quality in arid regions worldwide. We studied the effect of heat stress on wheat flour quality in heat tolerant cultivars to define the effects of heat stress on flour quality and to identify germplasm combining traits for heat tolerance and good flour quality. We studied the kernel phenotypic traits, the expression of seed storage proteins (SSPs), and the resulting flour quality under heat and normal conditions. Under heat stress, all cultivars yielded narrow-shaped seeds, and increased protein contents as compared to the control plants grown under normal conditions. The specific sedimentation values used to estimate the gluten quality varied between cultivars. We identified cultivars that could maintain good flour quality under heat stress conditions: ‘Imam’, which possessed the Glu-D1d allele responsible for the suitable bread-making; ‘Bohaine’, which displayed high expression level of SSPs; and ‘Condor’, which possessed slight variations in the ratio of each SSP under heat stress conditions. Combining the desirable traits from these cultivars could yield a wheat cultivar with heat tolerance and good flour quality.

A novel SNP of MYO1A gene associated with heat-tolerance in Chinese cattle

With the advent of global climate change, heat-tolerance is becoming more and more important to the sustainability of animal husbandry production systems. Previous studies have shown that MYO1A gene associated with pigmentation may be closely related to heat-tolerance in cattle. In this study, a novel missense mutation (NC_037332.1 g.56390345 A > G) was first detected in MYO1A in 891 individuals of 35 cattle breeds, which transformed the amino acid isoleucine into valine. The purpose of this study was to determine the allele frequencies distribution of this locus in Chinese indigenous cattle and to analyze the relationship between this locus and heat-tolerance. Further analysis showed that frequency of wild allele A decreased gradually from northern cattle to southern cattle, whereas frequency of mutant type allele G showed the opposite pattern, which was consistent with the distribution of various climatic conditions of China. Additionally, association analysis was carried out between genotypes and four climatic conditions (annual mean temperature (T), relative humidity (H), temperature-humidity index (THI) and average annual sunshine hours (100-cloudiness) (SR)). Analysis results showed that genotypes were significantly correlated with climatic conditions. Therefore, our results suggest that the novel SNP (rs209559414) is related to heat-tolerance trait of Chinese indigenous cattle.

QTL mapping for heat tolerance related traits using backcross inbred lines in wheat (Triticum aestivum L.)

Heat stress is one of the most limiting factors for the production of wheat. Global warming and consequent changes in climate adversely affect wheat plant growth and yield. To elucidate genetic basis and map heat tolerance traits, a set of 134 backcross inbred lines (BILs) derived from the cross between WH730/*2 HD2733 was used. The population was evaluated under late sown (LS) and very late sown (VLS) conditions, by exposing to heat stress during rabi season. Positive association of normalized difference vegetation index (NDVI), thousand grain weight (TGW), grain weight per spike (GWS), biomass and grain yield (GY) under both production conditions was observed. However, canopy temperature (CT) and days to heading (DH) showed negative correlation with GY under heat stress. A total of 9 Quantitative trait loci (QTL) were discovered on 7 chromosomes, which includes 4 QTLs in LS and 5 QTLs under VLS condition. Combining the results of these QTLs revealed a major stable QTL for DH (qDH_iari_5A) on chromosome 5A with 23% and 26% explaining phenotypic variance under both sowing conditions. QTL for NDVI was detected on chromosome 1B while QTL for SL and GY on chromosome 2A. The identified QTLs in the genomic regions could be targeted for genetic improvement and marker assisted selection for heat tolerance in wheat.

Physiological and Biochemical Responses of Two Cotton (Gossypium hirsutum L.) Cultivars Differing in Thermotolerance to High Night Temperatures during Anthesis

Heat stress constitutes a major threat to crop production, and according to climatic projections, night temperatures are expected to increase faster and to a greater extent compared to day temperatures. While extensive research has been dedicated to the effects of higher than optimum day temperatures on cotton physiology, metabolism, and yield, and while heat-tolerant cotton cultivars have been introduced, the responses of such heat-tolerant cultivars to high night temperatures have not been evaluated. The objective of this study was to assess the efficiency of heat-tolerant cultivars to high night temperatures stress by monitoring the physiological and biochemical responses of two cotton cultivars, differing in thermotolerance, subjected to higher than optimum night temperatures, during anthesis. To that end, growth chamber experiments were conducted using two cotton cultivars differing in thermotolerance, namely ST5288B2RF (thermosensitive) and VH260 (thermotolerant). Treatments consisted of normal day/night temperatures (32/24 °C) and high night temperatures (32/30 °C) for 2 weeks at flowering (approximately 8 eight weeks after planting). The results indicated that VH260 was more thermotolerant than ST5288 even under conditions of high night temperature stress, as it managed to maintain its net photosynthetic rates, cell membrane integrity, as well as pistil carbohydrate contents and ultimately achieved higher total reproductive weight. It was concluded that heat tolerance of thermotolerant cultivars selected under conditions of high day temperatures is also conserved under high night temperatures, while net photosynthetic rates and cell membrane integrity can be utilized as selection traits for heat tolerance under either high day or night temperatures.

Selection of Korean heat tolerant rice lines in West Java irrigated lowland agro-ecosystem

One condition in global climate change era is increasing of world temperature which is approaching critical point of rice plant adaptation. Thus, heat tolerant rice variety is needed. Indonesian Centre for Rice Research (ICRR) and RDA (Rural Development Administration) of Korea through ASEAN-Korean Economic Cooperatives collaborates to breed heat tolerant rice variety. In this regard, 150 BC1F5 recombinant inbred lines (RIL) along with 5 checks was tested following Augmented Design of five blocks. Transplanting was conducted at 21 days after sowing on 25 cm x 25 cm planting space in 2 m x 5 m square plots. The results showed that SR34132(41)-1-1-1 (13.00 t/ha) and SR34132(11)-1-1 -1 (11.65 t/ha) had higher yield than the best check Inpari 42 Agritan GSR (8.23 t/ha). The first line had big grain size (27.72 g) and medium productive tiller (15 tillers), while the second had more productive tiller (23 tillers) even though had low filled grain/panilce, seed set, and grain size (21.60 g). There were 69 lines having comparable yield with Inpari 42 Agritan GSR. Combining high yield with heat tolerance traits is feasible for Indonesian agro ecosystem condition. Further testing to confirm the tolerance of the lines to heat stress is needed.

Four Novel SNPs of MYO1A Gene Associated with Heat-Tolerance in Chinese Cattle.

Simple SummaryChinese indigenous cattle were clustered into two groups of southern and northern breeds. The populations distributed in the hot south are mainly dominated by Bos indicus, and the populations distributed in the cold north are mainly dominated by Bos taurus. Myosin-1a (MYO1A) gene is a candidate gene related to pigmentation, which may be closely related to the heat tolerance traits of cattle. Therefore, our study aimed to explore the relationship between MYO1A gene and heat tolerance in Chinese indigenous cattle. Based on the previous GWAS research related to bovine heat tolerance trait, this study aimed to explore the effect of myosin-1a (MYO1A) gene on bovine heat tolerance trait, and find the molecular markers related to the heat tolerance of Chinese cattle. In our study, four novel candidate SNPs highly conserved in B. indicus breeds but barely existed in B. taurus were identified in MYO1A gene according to Bovine Genome Variation Database and Selective Signatures (BGVD). PCR and DNA sequencing were used to genotype 1072 individuals including 34 Chinese indigenous cattle breeds as well as Angus and Indian zebu. Two synonymous mutations (rs208210464 and rs110123931), one missense mutation (rs209999142; Phe172Ser), and one intron mutation (rs135771836) were detected. The frequencies of mutant alleles of the four SNPs gradually increased from northern groups to southern groups of Chinese cattle, which was consistent with the distribution of various climatic conditions of China. Additionally, four SNPs were significantly associated with four climatic conditions including annual mean temperature (T), relative humidity (H), temperature-humidity index (THI), and average annual sunshine hours (100-cloudiness) (SR). Among these, rs209999142 and Hap 1/1 had better performance than others. Our results suggested that rs209999142 was associated with heat-tolerance trait and rs208210464, rs110123931, and rs135771836 showed high phenotypic effect on heat-tolerance trait because of the strong linkage with rs209999142. These SNPs could be used as candidates for marker-assisted selection (MAS) in cattle breeding.