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The North African catfish (Clarias gariepinus) is a significant species in aquaculture, which is crucial for ensuring food and nutrition security. Their high adaptability to diverse environments has led to an increase in the number of farms that are available for their production. However, long-term closed breeding adversely affects their reproductive performance, leading to a decrease in production efficiency. This is possibly caused by inbreeding depression. To investigate the root cause of this issue, the genetic diversity of captive North African catfish populations was assessed in this study. Microsatellite genotyping and mitochondrial DNA D-loop sequencing were applied to 136 catfish specimens, collected from three populations captured for breeding in Thailand. Interestingly, extremely low inbreeding coefficients were obtained within each population, and distinct genetic diversity was observed among the three populations, indicating that their genetic origins are markedly different. This suggests that outbreeding depression by genetic admixture among currently captured populations of different origins may account for the low productivity of the North African catfish in Thailand. Genetic improvement of the North African catfish populations is required by introducing new populations whose origins are clearly known. This strategy should be systematically integrated into breeding programs to establish an ideal founder stock for selective breeding. [ABSTRACT FROM AUTHOR]

Mulberries are vital for the silk industry as the sole natural food for silkworms, but their quality and quantity can be greatly impacted by environmental factors, notably water shortages or droughts. In this study, the proline content and expression levels of the Pyrroline-5-carboxylate reductase (P5CR) gene in four recommended Thai mulberry varieties (Sakhonnakorn, Sakhonnakorn 85, Burirum 60, and Srisaket 84) and one standard drought tolerant variety (SRCM9809-34) were measured under drought stress. Additionally, physiological data and antioxidative enzymatic activities were also examined. The findings revealed that SRCM9809-34, a drought-tolerant variety, had the lowest proline content, followed by Sakhonnakorn 85, Burirum 60, while the highest proline content was observed in Srisaket 84. Although there was no correlation between the expression level of the P5CR gene and proline content, the overall trend in all varieties was the same: proline content increased after drought conditions. Regarding physiological responses, the wilting score showed similar results to proline content, with SRCM9809-34 having the lowest proline content and wilting score. Moreover, SRCM9809-34 exhibited the highest RWC, Pn and WUE values, as well as the lowest level of MDA and H2O2. Our results validated and indicated that SRCM9809-34 is a drought-tolerant variety. From this finding, among the four Thai mulberry varieties, Sakhonnakorn 85 exhibited the highest potential for drought tolerance, and this potential can be enhanced through crossbreeding with SRCM9809-34. [ABSTRACT FROM AUTHOR]

Rice blast is one of the most destructive diseases of rice and is caused by the fungus Magnaporthe oryzae. The disease causes enormous yield losses in rice production worldwide. The rice blast fungus delivers effector proteins into rice cells. The effector proteins play an essential role in fungal virulence by manipulating and controlling host cellular pathways and inhibiting host immune responses to enhance pathogenicity. An effector gene, AvrPi9, which corresponds to the resistance gene Pi9, was cloned and characterized. However, a regulatory molecular mechanism for AvrPi9 gene expression has not been determined. In this study, the genetic variation of the AvrPi9 and its promoter function were characterized. The results showed that 98% (116/118) of the samples carried the AvrPi9 gene without any sequence variation, whilst two isolates, 10576 from Kalasin and NYK56003 from Nakhon Nayok, lacked the AvrPi9 gene. A homeobox domain‐containing protein (MoHOX6) was identified as a candidate transcription factor. The AvrPi9 gene expression was delayed in the MoHOX6 knockout mutant. Moreover, the AvrPi9 promoter was able to drive the expression of a luciferase gene in rice protoplasts. This study provides the first insight into the function and regulation of the AvrPi9 promoter of rice blast fungus. [ABSTRACT FROM AUTHOR]

Rice blast disease, caused by the filamentous fungus Pyricularia oryzae, is one of the most destructive diseases in rice worldwide. Breeding of resistant rice cultivars remains a cost‐effective and environment‐friendly means for controlling blast disease, but the resistance tends to break down over time because of the pathogen's rapid adaptation. In this study, AVRPiz‐t gene sequences of 46 rice blast isolates were evaluated using a Southern blot analysis. The AVRPiz‐t gene was present in 24 of 46 (52.2%) rice blast isolates. The pathogenicity assay showed that all blast isolates were avirulent against Japanese rice cv. Toride 1, which carries several rice blast resistance genes including Piz‐t, Pii, Pi37, and Pi‐ta. Screening for the Piz‐t gene in Thai rice germplasm revealed that less than 20% of rice varieties harbour the Piz‐t gene. Therefore, the Toride 1 rice variety could serve as an effective donor of rice blast resistance to be used in rice breeding programmes in Thailand. This study provides evidence for co‐evolution between the rice blast resistance gene Piz‐t and the rice blast fungal avirulence gene AVRPiz‐t. Understanding this relationship will facilitate the sustainable development of breeding for rice blast resistance in the future. [ABSTRACT FROM AUTHOR]

Genetic variation of the rice blast (Pyricularia oryzae) population in Thailand was investigated based on the nucleotide sequence of three avirulence genes, AVR‐Pi9, AVR‐Pik, and AVR‐Pita1. Sixty rice blast isolates were collected from rice‐growing areas around Thailand. Gene‐specific primers were used to amplify these AVR genes and AVR‐Pi9, AVR‐Pik, and AVR‐Pita1 were detected in 60, 57, and 23 isolates, respectively. Based on the AVR‐Pi9 sequences, we identified one rice blast isolate containing an amino acid change from glutamic acid to aspartic acid. Moreover, two rice blast isolates had identical sequences to the rice blast strain originating in Japan, indicating a potential movement of this isolate from Japan to Thailand. Three AVR‐Pik alleles were found, including AVR‐PikA (3.51%), AVR‐PikD (71.93%), and isolates with two copies of AVR‐PikD and AVR‐PikF (24.56%). AVR‐PikA and AVR‐PikF are virulent to Thai rice variety Jao Hom Nin. Six haplotypes of AVR‐Pita1 were identified with one deletion and 12 amino acid substitutions. This study revealed that different AVR genes in Thai rice blast populations have different levels of genetic variation: AVR‐Pi9 and AVR‐Pik genes have a relatively low genetic diversity, while the AVR‐Pita1 gene has high genetic diversity. We found AVR‐Pi9 was not under selection pressure, while AVR‐Pita1 was under purifying selection pressure. In addition, geographic location has influenced the distribution of genetic variation of AVR‐Pita1. The information obtained from this study is valuable for the future development of breeding strategies for rice blast resistance in Thailand. [ABSTRACT FROM AUTHOR]