Abstract
Oryza sativa 'Dahanala' is a traditional red rice variety acknowledged for its thrips resistance. This study focused on the genetic diversity assessment of Dahanala accessions in Sri Lanka. Twenty-six Dahanala accessions conserved at the genebank of the Plant Genetic Resources Centre and six accessions from the Rice Research and Development Institute, Batalagoda, were analyzed using seven seed morphology characters followed by molecular characterization with 31 simple sequence repeat markers, showing a significant genetic variation of the accessions. Accessions 003924/003327 and 0010160/006165 were reported as two potential pairs of duplicates. The polymorphic information content values varied between 0 (RM255) and 0.697 (RM412). Genetic distance ranged within 0.0 and 0.94 revealing considerable genetic variance. Sixteen closely related accessions were selected as a representative set of Dahanala, including accessions 003924, 003327, 006376, 010160, 006165, 006378, 004968, 003304, 006739, 005386, 004507, 003149, 003131, 627, 626 and 629. To assess the variation of trichome phenotypes among Dahanala accessions, leaf trichome density as well as RM277 and RM279 markers, which carry a putative relationship with thrips resistance, were used as morphological and molecular markers, respectively. Results revealed a variation of trichome density from 6.7 to 30.83 trichomes/mm2. According to the molecular marker analysis, both markers revealed polymorphism in thrips-resistant Dahanala accessions and susceptible Oryza sativa ‘Suduru Samba’ accessions, but no clear linkage between the markers and trichome phenotypes within the selected Dahanala accessions could be found. Further studies are needed to dissect the relationship between trichome phenotype and thrips resistance in red rice.
Highlights
Lemma and palea colour are classified into 19 classes (7.5.5): 0) Straw 1) Gold and/or gold furrows on straw background 2) Brown spots on straw 3) Brown furrows on straw 4) Brown 5) Reddish to light purple 6) Purple spots on straw background 7) Purple furrows on straw background 8) Purple 9) Black 10) White 11) Brownish black 12) Yellowish gray 13) Yellowish brown 14) Brown furrows on gold background 15) Reddish brown spots on gold background 16) Black spots on straw background 17) Brownish black furrows on gold background 18) Brownish black furrows on straw background 19) Brown furrows on yellowish background
Grain length (7. 5. 15): Time: At maturity, grain length is measured as the distance from the base of the lowermost sterile lemma to the tip of the fertile lemma or palea, whichever is longer
Grain width (7. 5. 16): Time: At maturity, width of grain is measured in millimeters as the distance across the fertile lemma and the palea at the widest point
Summary
2. Lemma and palea colour are classified into 19 classes (7.5.5) (modified): 0) Straw 1) Gold and/or gold furrows on straw background 2) Brown spots on straw 3) Brown furrows on straw 4) Brown 5) Reddish to light purple 6) Purple spots on straw background 7) Purple furrows on straw background 8) Purple 9) Black 10) White 11) Brownish black 12) Yellowish gray 13) Yellowish brown 14) Brown furrows on gold background 15) Reddish brown spots on gold background 16) Black spots on straw background 17) Brownish black furrows on gold background 18) Brownish black furrows on straw background 19) Brown furrows on yellowish background
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