Tonapha Pusadee

Complexity and adaptability of a traditional agricultural system: case study of a gall midge resistant rice landrace from northern Thailand

Adaptability of traditional agricultural systems is suggested by their success over time, but documentation of how this happens is rare. This paper shows how genetic diversity in a rice landrace enables rice farming system of northern Thailand to adapt to a constraint of an insect pest, microenvironments of mountainous landscape and people’s different tastes in rice. Resistance to laboratory-reared gall midge varied among accessions the rice landrace Muey Nawng and gall midge populations. Higher rice yield in farmers’ fields reflected adaptation to local environment as well as resistance to gall midge. Microsatellite variation of the accessions correlated negatively with their gall midge resistance, but there was also variation in heading time and endosperm starch. Presence of non-waxy endosperm in glutinous rice provides opportunity to select for rice that is cooked into non-glutinous rice preferred by minority groups who live at higher elevations, where the gall midge is emerging as a new threat, possibly because of climate change. These data show how genetic diversity of a rice landrace coupled with seed management by farmers enabled a rice farming system to adapt to the varied microenvironment of a mountainous landscape under the constraint of an insect pest and people’s different tastes in rice.

Variation of floral traits in Thai rice germplasm (Oryza sativa)

Floral traits play an important role in mating systems in flowering plant species. In rice, variation in floral traits has been established in a wide range of germplasm, but the variability of floral traits in Thai rice remains uncharacterized. Sixty-seven rice varieties that are cultivated throughout the country and two accessions of common wild rice were evaluated for nine floral traits to assess the extent of variation, and the differentiation of floral traits among groups of rice (improved rice varieties, selected traditional varieties, local traditional varieties and wild rice). The range of variation of all traits examined in Thai rice varied within the extent of variation that has been reported in other rice germplasm. Most of the floral traits observed in Thai rice have mean values similar to other reports, except in stamen traits, percentage of stigma exertion and the length of spikelet, which exhibited higher mean values than other germplasm investigations. Since these floral traits have a large contribution on outcrossing potential, Thai rice might have a greater chance of natural outcrossing compared to other cultivated rice germplasm. There is no clear differentiation in floral traits among groups of cultivated rice, but there are obvious differences in most of the floral traits between cultivated rice varieties and common wild rice, illustrated in the transformation of rice floral structures during domestication. The results have implications for outcrossing and spontaneous gene flow as well as a potential use in the parental lines for hybrid rice seed production.

Genetic relationships between anther and stigma traits revealed by QTL analysis in two rice advanced-generation backcross populations

Anther and stigma size are critical floral traits that influence outcrossing in rice (Oryza sativa), a crop that is predominantly self-fertilizing. The efficiency of hybrid rice seed production depends on efficient outcrossing ability of parental lines, which is promoted by increased anther and stigma size. Phenotypic correlations between anther and stigma traits have been observed in many studies; however, evidence for this relationship is unclear and the genetic basis remains to be elucidated. To examine this relationship and to identify quantitative trait loci (QTLs) for increased anther and stigma size, we developed two advanced backcross QTL mapping populations derived from a cross between a Thai elite indica crop variety (SPR1) and an accession of common wild rice (O. rufipogon Griff.), which is predominantly outcrossing. One mapping population was selected for increased anther size while the other was selected for increased stigma size. We mapped QTLs for anther size and stigma size in both populations. Bulked segregant analysis was used to identify molecular markers associated with the selected traits. A total of 16 significant QTLs associated with anther and stigma traits were identified across the two populations, and these were located in five genomic regions on four chromosomes. Whereas three of these regions have been previously reported, two of them are newly identified and should be further explored for improving outcrossing ability in rice. The co-localization of QTL for anther and stigma traits strongly suggests some degree of shared developmental basis for these traits.

Phenotypic and Genetic Diversity of Local Perilla (Perilla frutescens (L.) Britt.) from Northern Thailand

Phenotypic and Genetic Diversity of LocalPerilla(Perilla frutescens(L.) Britt.) from Northern Thailand.Perilla frutescens (L.) Britt., an important oil and culinary crop in Asia, is a valuable genetic resource. Despite its nutritional value and historic and cultural importance, research on Perilla has been scarce, particularly as far as its genetic diversity is concerned. The aims of the present study were to assess variability within and between 29 seed samples of P. frutescens collected from farmers in northern Thailand, and evaluation conducted of their genetic, morphological, and agronomic characteristics, and the seed composition, including polyunsaturated fatty acids omega-3, omega-6, and omega-9, and the vitamin E γ-tocopherols. Perilla frutescens (L.) Britt. of northern Thailand is genetically variable, and structured according to origin of collection which was the consequence of local adaptation. The discovery of high levels of polyunsaturated fatty acids, namely α-linolenic acid and γ-tocopherols, in some Perilla samples indicates the potential for utilizing Perilla for its high omega-3 content including as a vitamin E supplement for humans, a prospect that should be taken into account when planning conservation strategies or when Perilla variability is used in breeding programs.Phenotypic and Genetic Diversity of LocalPerilla(Perilla frutescens(L.) Britt.) from Northern Thailand. งาขี้ม้อน (Perilla frutescens (L.) Britt.) เป็นแหล่งพันธุกรรมที่มีคุณค่า เป็นพืชน้ำมัน และสมุนไพรที่สำคัญในอาเซีย นอกจากคุณค่าทางโภชนาการที่สูง และความสำคัญทางประวัติศาสตร์และวัฒนธรรมแล้ว ข้อมูลเกี่ยวกับงาขี้ม้อนถือว่ายังมีน้อยโดยเฉพาะอย่างยิ่งในแง่ความหลากหลายทางพันธุกรรม งานวิจัยนี้จึงมีวัตถุประสงค์เพื่อประเมินความหลากหลายทางพันธุกรรมในประชากรงาขี้ม้อนจำนวน 29 ตัวอย่างที่เก็บมาจากแปลงเพาะปลูกของเกษตรกรในเขตภาคเหนือของประเทศไทย โดยประเมินลักษณะทางสัณฐาน พืชไร่ กรดไขมันอิ่มตัว ได้แก่ โอเมก้า-3 โอเมก้า-6 และ โอเมก้า-9 และวิตามินอี-แกมม่าโทโคฟีรอล และเพื่อประเมินระดับความหลากหลายทางพันธุกรรม ความสัมพันธ์ภายใน และระหว่างประชากร พบว่างาขี้ม้อนในเขตภาคเหนือของประเทศไทยมีความแปรปรวนทางพันธุกรรม และมีโครงสร้างประชากรแยกตามพื้นที่ที่เก็บตัวอย่างซึ่งเป็นผลมาจากกระบวนการปรับตัวต่อสภาพพื้นที่ งาขี้ม้อนบางประชากรมีปริมาณโอเมก้า-3 และแกมมาโทโคฟีรอลสูงแสดงให้เห็นถึงศักยภาพในการนำงาขี้ม้อนมาใช้ประโยชน์ในแง่เป็นอาหารเสริมให้กับมนุษย์ จากผลการวิจัยที่ได้ถือว่าเป็นมุมมองที่สำคัญหากต้องการวางแผนวิธีการในงานอนุรักษ์พันธุ์งาขี้ม้อน และนำความหลากหลายนี้ไปใช้ประโยชน์ในโครงการปรับปรุงพันธุ์

Chemical composition and comparison of genetic variation of commonly available Thai garlic used as food supplement

In order to classify true garlic cultivars, comparisons of oil composition and genetic of three garlic cultivars ( Allium sativum L.) commonly used for essential oil production in the northern Thai market [viz., Thai (TH), Chinese (CH) and Pingpong (PP) cultivars] were carried out. Garlic essential oils were obtained by hydrodistillation and microwave hydrodistillation which were then analysed for chemical components by gas chromatography-mass spectrometry. The RAPD data suggests similarity (>95%) of the three cultivars in chemical compositions, and the major compounds are trisulphide, di-2-propenyl, the disulphide, di-2-propenyl, and the trisulphide, methyl 2-propenyl. Sulphur-containing compounds (Rf = 0.18-0.2) were detected by thin-layer chromatography (TLC) with ninhydrin staining reagent. The essential oil of CH from hydrodistillation and microwave hydrodistillation showed the highest alliin content. The RAPD analysis of the three garlic cultivars presents 45 fragments. A dendrogram shows genetic similarity between the garlic cultivars. The TH and the CH showed similarity value as 0.93, while the PP was classified as a different cluster. Though there was considerable similarity between the chemical and the genetic profiles of the TH and the CH, the CH demonstrated high potential as an ingredient in food supplement products due to its high alliin content.