RESUMEN
This study aims to discriminate the geographical origin of Thai Hom Mali rice in order to protect consumers from mislabeling. Stable isotopic and elemental compositions (δ13C, δ15N, δ18O, As, Br, K, Mn, Rb, and Zn) of Thai Hom Mali rice cultivated inside and outside the Thung Kula Rong-Hai Plain were combined with chemometric analysis, linear discriminant analysis (LDA) and partial least squares-discriminant analysis (PLS-DA). The 9 variables combined with LDA can distinguish Thai Hom Mali rice cultivated inside and outside the Thung Kula Rong-Hai Plain with 98.2 % correct classification and 94.6 % cross-validation. The efficiency in using stable isotopic and elemental compositions combined with soft PLS-DA was achieved 100 % in discrimination of Thai Hom Mali rice cultivated inside and outside the Thung Kula Rong-Hai Plain. The variables δ15N, Br, K, and Rb were key parameters to discriminate the geographical origin of Thai Hom Mali rice.
RESUMEN
Tropical lotus (Nelumbo) is an important and unique ecological type of lotus germplasm. Understanding the genetic relationship and diversity of the tropical lotus is necessary for its sustainable conservation and utilization. Using 42 EST-SSR (expressed sequence tag-simple sequence repeats) and 30 SRAP (sequence-related amplified polymorphism) markers, we assessed the genetic diversity and inferred the ancestry of representative tropical lotus from Thailand and Vietnam. In total, 164 and 41 polymorphic bands were detected in 69 accessions by 36 EST-SSR and seven SRAP makers, respectively. Higher genetic diversity was revealed in Thai lotus than in Vietnamese lotus. A Neighbor-Joining tree of five main clusters was constructed using combined EST-SSR and SRAP markers. Cluster I included 17 accessions of Thai lotus; cluster II contained three Thai accessions and 11 accessions from southern Vietnam; and cluster III was constituted by 13 accessions of seed lotus. Consistent with the results from the Neighbor-Joining tree, the genetic structure analysis showed that the genetic background of most Thai and Vietnamese lotus was pure, as artificial breeding has been rare in both countries. Furthermore, these analyses indicate that Thai and Vietnamese lotus germplasms belong to two different gene pools or populations. Most lotus accessions are genetically related to geographical distribution patterns in Thailand or Vietnam. Our findings showed that the origin or genetic relationships of some unidentified lotus sources can be evaluated by comparing morphological characteristics and the data of molecular markers. In addition, these findings provide reliable information for the targeted conservation of tropical lotus and parent selection in breeding novel cultivars of lotus.
RESUMEN
To investigate UVB DNA damage response in higher plants, we used a genetic screen to isolate Arabidopsis thaliana mutants that are hypersensitive to UVB irradiation, and isolated a UVB-sensitive mutant, termed suv2 (for sensitive to UV 2) that also displayed hypersensitivity to gamma-radiation and hydroxyurea. This phenotype is reminiscent of the Arabidopsis DNA damage-response mutant atr. The suv2 mutation was mapped to the bottom of chromosome 5, and contains an insertion in an unknown gene annotated as MRA19.1. RT-PCR analysis with specific primers to MRA19.1 detected a transcript consisting of 12 exons. The transcript is predicted to encode a 646 amino acid protein that contains a coiled-coil domain and two instances of predicted PIKK target sequences within the N-terminal region. Fusion proteins consisting of the predicted MRA19.1 and DNA-binding or activation domain of yeast transcription factor GAL4 interacted with each other in a yeast two-hybrid system, suggesting that the proteins form a homodimer. Expression of CYCB1;1:GUS gene, which encodes a labile cyclin:GUS fusion protein to monitor mitotic activity by GUS activity, was weaker in the suv2 plant after gamma-irradiation than in the wild-type plants and was similar to that in the atr plants, suggesting that the suv2 mutant is defective in cell-cycle arrest in response to DNA damage. Overall, these results suggest that the gene disrupted in the suv2 mutant encodes an Arabidopsis homologue of the ATR-interacting protein ATRIP.