Genetics Analysis and Heritability of Fruit Characters in Muskmelon (Cucumis Melo L.) Using Extreme Parental Differences

Taeng-Thai is the Thai name for oriental pickling melon or muskmelon (Cucumis melo L.) which is a Cucumis species. Based on consumption as Thai traditional dessert, fruit characters at ripening stage are very important to improve the muskmelon cultivar. Understanding the genetic control of fruit traits is the key to a successful for crop improvement. Research aimed to determine the genetic effects, number of genes and heritability of fruit characters in muskmelon. The results have shown that both additive and dominant effects governed for fruit weight, fruit length, fruit width and fruit thickness with the number of gene as 40.26, 1.55, 10.70 and 11.10 genes, respectively. Simple phenotypic correlation coefficients shown, had a significant positive correlation among the four fruit traits. Due to the quantitative inheritance of fruit characters, quantitative traits loci (QTL) mapping of those traits were necessary to identify all controlling genes of fruit traits in further muskmelon improvement

Genetic diversity analysis of rice cultivars ( Oryza sativa L.) differing in salinity tolerance based on RAPD and SSR markers

Thirty rice cultivars were evaluated for salinity tolerance during the seedling stage and were divided into five tolerance groups including tolerant (T), moderately tolerant (MT), moderately susceptible (MS), susceptible (S) and highly susceptible (HS) which comprised 5, 10, 9, 4 and 2 cultivars respectively. Genetic diversity of all rice cultivars was evaluated using random amplified polymorphic DNA (RAPD) and simple sequence repeats (SSR) markers. The cultivars were evaluated for polymorphisms after amplification with 20 random decamer primers and 20 SSR primer pairs. A total of 161 RAPD markers and 190 SSR alleles were produced which revealed 68.94% and 89.47% polymorphism respectively. Mean genetic similarity coefficient was 0.82 for RAPD and 0.70 for SSR. Cluster analysis based on RAPD markers was effective in grouping cultivars based on their salt tolerance ability. Group IA1, IB and IV contained three T, three S and two HS rice cultivars respectively. The MT and MS cultivars which showed similar physiological responses to salinity were resolved into two groups: Group IA2 and Group II comprising ten and eight MT/MS cultivars respectively. Cluster analysis based on SSR markers separated rice cultivars into groups based on genetic relatedness which did not correspond to salinity tolerance level. The results from this study provided some useful implications for salt tolerance breeding programs. The evaluation of genetic similarity and cluster analysis together with salt tolerance ability provides some useful guides for assisting plant breeders in selecting suitable genetically diverse parents for the crossing program

Stability of Four New Sources of Bacterial Leaf Blight Resistance in Thailand Obtained From Indigenous Rice Varieties

Bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious diseases in rice production. Breeding varieties specifically for their resistance to BLB disease is therefore an efficient and cost-effective strategy. However, the resistance gene for BLB can be race and non-race specific, meaning it is often overcome by the pathogen. The identification of new sources of resistance genes for Xoo is crucial in rice breeding programmes. In this study, six rice varieties were assessed using six Xoo isolates in multiple screening conditions. The GGE biplot analysis considers both genotype (G) and genotype environment (GE) interaction effects and demonstrates GE interaction. The first two principal components (PCs) accounted for 95.46% of the total GE variation in the data. Based on lesion length and stability performance, Phaladum was the most ideal genotype against all Xoo isolates in the four screening conditions. The results relayed that Phaladum indigenous rice varieties could be considered as new sources of bacterial leaf blight resistance in Thailand. In the future, the BLB resistance gene in this variety will be identified in regard to mode of inheritance and used as parental line in rice breeding programmes for resistance to BLB

Variability in Prolificacy, Total Carotenoids, Lutein, and Zeaxanthin of Yellow Small-Ear Waxy Corn Germplasm

Waxy corn is a popular, alternative staple food in most Asian countries including Thailand. The availability of small-ear waxy corn genotypes with prolific ears and a high level of carotenoids is expected to benefit growers and consumers. Integrated evaluation among source germplasm is essential before performing further breeding efforts for enhancing prolific ears and high-carotenoid content. Thus, the present study explored the variability of ear prolificacy, total carotenoids, lutein, zeaxanthin, and beta-carotene among yellow small-ear waxy corn accessions. About 44 corn accessions and 4 check varieties were evaluated for agronomic traits and yield components under multienvironment trials in a randomized complete block design (RCBD). The immature seed sample of these genotypes was analyzed to quantify the content of total carotenoids and some carotenoid fractions. All traits showed that low GXE interaction and significant genotypic diversity existed among all tested accessions with the predominant contribution of genotype to total phenotypic variation and beta-carotene. Accessions were clustered into four major groups based on the similarity of multiple carotenoids profiles. Three selected accessions (UT121001, KKU-WX112087, and KKU-WX212001) had higher values of total carotenoids, lutein, zeaxanthin, and beta-carotene than those of all check varieties. High and positive correlations among second-emerged ears, marketable second-emerged ears, and total ear number indicate that a higher chance of secondary ears becomes marketable ears with an increase of total ears per plant per hectare. Lutein and zeaxanthin had positive, strong correlations with total carotenoids. The implications and breeding strategies are discussed prior to promoting yellow small-ear waxy corn as a biofortified crop

Application of LW7 marker for identification of progenies with male sterility gene in sweet sorghum population

The objectives of this study were to verify the use of LW7 marker in identifying maintainer lines (B-lines) and restorer lines (R-lines) in grain sorghum and sweet sorghum, and to identify B-lines in the F2, BC1F2 and BC2F2 generations. Twenty five accessions of sorghum were evaluated, and LW7 marker correctly identified accessions which presented male sterility gene (rf4) in Suphan Buri1 and 03B cultivars; moreover, these genotypes did not show 779 bp band. The cross between Suphan Buri1 and a male-sterile line (A-line) 03A resulted in a sterilized male, confirming the usefulness of the marker in breeding programs. B-lines in the F2, BC1F2 and BC2F2 generations were identified by LW7 marker. The segregation ratio of 3:1 for male fertility and male sterility in the progenies of the three generations supported the one-gene model of Mendelian segregation. The use of marker assisted selection was successful for line development of sweet sorghum with male sterilit

Genetics Analysis and Heritability of Fruit Characters in Muskmelon (Cucumis melo L.) Using Extreme Parental Differences

Taeng-Thai is the Thai name for oriental pickling melon or muskmelon (Cucumis melo L.) which is a Cucumis species. Based on consumption as Thai traditional dessert, fruit characters at ripening stage are very important to improve the muskmelon cultivar. Understanding the genetic control of fruit traits is the key to a successful for crop improvement. Research aimed to determine the genetic effects, number of genes and heritability of fruit characters in muskmelon. The results have shown that both additive and dominant effects governed for fruit weight, fruit length, fruit width and fruit thickness with the number of gene as 40.26, 1.55, 10.70 and 11.10 genes, respectively. Simple phenotypic correlation coefficients shown, had a significant positive correlation among the four fruit traits. Due to the quantitative inheritance of fruit characters, quantitative traits loci (QTL) mapping of those traits were necessary to identify all controlling genes of fruit traits in further muskmelon improvement

The Basic Vegetative Phase and Photoperiod Sensitivity Index as the Major Criteria for Indigenous Upland Rice Production in Thailand under Unpredictable Conditions

Indigenous upland rice (Oryza sativa L.) is an important staple food for people. The productivity of upland rice is generally lower than lowland rice since crop yield depends on the amount of rainfall. Climate change is a major problem in rice production due to the unpredictable rainfall. The flowering time, maturity days, growth duration, and photoperiod sensitivity in rice are important for determining productivity. Therefore, in this study, indigenous upland rice germplasm was classified according to their flowering-related traits in the basic vegetative phase (BVP), photoperiod sensitivity index (PSI), grain yield (GY), and yield components. The results reveal that the BVP ranges from 12 to 76 days (mainly less than 30 days) while the PSI ranges from −0.14 to 0.89. Classification of the three groups was based on the PSI: 24 insensitivities (G1; PSI = −0.14–0.30), 214 weakly sensitive (G2; PSI = 0.31–0.70), and 63 strongly sensitive (G3; PSI = 0.71–0.89). Grain yield showed different correlations with day to flowering (DTF), PSI, and BVP in each group. The results suggest that the selection criteria were not only based on GY and DTF but also PSI and BVP. The new ideotypes for upland rice selection under unpredictable conditions such as rainfall and light duration are weakly sensitive (PSI range 0.30–0.60), low BVP (20–30 days), and less than 105 days of DTF, such as ULR189, ULR039, ULR036, ULR403, ULR364, ULR342, and ULR245 genotypes

The Basic Vegetative Phase and Photoperiod Sensitivity Index as the Major Criteria for Indigenous Upland Rice Production in Thailand under Unpredictable Conditions

Indigenous upland rice (Oryza sativa L.) is an important staple food for people. The productivity of upland rice is generally lower than lowland rice since crop yield depends on the amount of rainfall. Climate change is a major problem in rice production due to the unpredictable rainfall. The flowering time, maturity days, growth duration, and photoperiod sensitivity in rice are important for determining productivity. Therefore, in this study, indigenous upland rice germplasm was classified according to their flowering-related traits in the basic vegetative phase (BVP), photoperiod sensitivity index (PSI), grain yield (GY), and yield components. The results reveal that the BVP ranges from 12 to 76 days (mainly less than 30 days) while the PSI ranges from −0.14 to 0.89. Classification of the three groups was based on the PSI: 24 insensitivities (G1; PSI = −0.14–0.30), 214 weakly sensitive (G2; PSI = 0.31–0.70), and 63 strongly sensitive (G3; PSI = 0.71–0.89). Grain yield showed different correlations with day to flowering (DTF), PSI, and BVP in each group. The results suggest that the selection criteria were not only based on GY and DTF but also PSI and BVP. The new ideotypes for upland rice selection under unpredictable conditions such as rainfall and light duration are weakly sensitive (PSI range 0.30–0.60), low BVP (20–30 days), and less than 105 days of DTF, such as ULR189, ULR039, ULR036, ULR403, ULR364, ULR342, and ULR245 genotypes

Effects of Salt Stress after Late Booting Stage on Yield and Antioxidant Capacity in Pigmented Rice Grains and Alleviation of the Salt-Induced Yield Reduction by Exogenous Spermidine

Pigmented rice is receiving much attention due to the large amounts of bioactive compounds and various health benefits.However, little information is available on its agronomic and physiological aspects. This research aimed to explore the effects of salinity on yield and grain quality of pigmented rice and the modulation of salinity responses by exogenous application of spermidine (Spd). Four cultivars of rice were grown in pots until the early booting stage. Thereafter, the plants were sprayed with 1 mM Spd for 7 successive days before being irrigated with 25 mM NaCl instead of tap water until maturity. Grain yield, yield components and harvest index in all rice cultivars were negatively affected by this salinity stress. Pretreatment with Spd dramatically improved yield and yield components of salt-treated plants, particularly the salt-sensitive cultivar. The major yield components which were improved and contributed most to the dramatic increase in seed yield were the number of filled grains per panicle and panicle fertility. Moreover, Spd pretreatment resulted in an increase in K+/Na+ ratio in rice grains. Salt stress increased nutritional quality of mature grains, i.e., total phenolic content, anthocyanins, proanthocyanins and antioxidant activities (evaluated by FRAP, DPPH and ABTS assays) in all rice cultivars. Furthermore, all aspects of health-promoting nutritional characters were further enhanced by Spd pretreatment. Thus foliar spraying of Spd to rice plants prior to salt application improved grain yield as well as nutritional quality of colored rice grains in relation to total phenolics, flavonoid pigments and antioxidant capacities