Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 29, 2004
Publication Date: February 1, 2005
Citation: Eizenga, G.C., Ho, Q.P. 2005. Introduction and identification of IR36 rice trisomic lines. Rice Technical Working Group Meeting Proceedings. Abstract p. 69-70. Technical Abstract: Trisomic rice (Oryza sativa L.) plants (2n=2x=24) are plants that have an additional chromosome (2n=2x=25). Presence of a third chromosome alters segregation ratios which makes trisomics lines helpful for a) locating a gene on a particular chromosome, b) verifying the independence of linkage groups, c) associating the genetic linkage groups with individual chromosomes or d) incorporating alien variation. Complete series of rice trisomic lines are available worldwide in three backgrounds: IR36 - an indica cultivar developed by IRRI, Nipponbare - a Japanese temperate rice cultivar, and Zhongxian 3037 - a Chinese indica cultivar. In addition to primary trisomic lines with an additional complete chromosome, each of these trisomic series has various secondary trisomic (double chromosome arm) lines, telotrisomic (single chromosome arm) lines and/or alien (non-O. sativa chromosome) addition lines. In an effort to incorporate the IR 36 trisomic series into the US germplasm collection, all twelve IR36 primary trisomic lines, secondary trisomic (1S.1S, 2S.2S, 5S.5S, 6S.6S, 6L.6L, 7S.7S, 8S.8S, 8L.8L, 11S.11S, 11L.11L, 12S.12S) and telotrisomic (2L, 3L, 5L, 7S, 9S, 12S) IR36 lines were obtained from IRRI. These lines were grown in the rice quarantine greenhouse at Fayetteville, Arkansas using three different grow-outs from 1999-2001. When the quarantine plants were near maturity, the supposed trisomic plants were identified based on morphology and heading date. For most trisomic lines, one to three plants were identified from the grow-out. The selected lines were grown in the field at Stuttgart, Arkansas during the summers of 2000-2003. Seed were planted as space plants, one seed per hill. The control, IR36 was planted for comparison at every sixth row or fourth row, 2000-01 and 2003, respectively. In 2003 the row spacing was increased to account for the excessive tillers and lodging problems inherent in IR36 grown in an Arkansas management system. Plants were observed throughout the growing season. Panicles for meiotic analysis were collected as the flag leaf emerged at the R1-R2 growth stage. Later, panicles with mature seed were collected from supposed trisomics based on morphological observation at maturity. Of the twelve primary trisomic lines selected based on morphology from the quarantine grow-out, eleven had the correct morphology when grown in Stuttgart. To date, the nine primary trisomic lines confirmed by cytological observation are T1, T2, T3, T4, T7, T8, T9, T11 and T12. Of the eleven secondary trisomic lines selected based on morphology in the quarantine grow out, nine had the correct morphology when grown in Stuttgart. To date, the four secondary trisomics confirmed by cytological observation are 7S.7S, 8S.8S, 8L.8L and 11L.11L. Lastly, of the nine telotrisomic lines grown in quarantine, six had the correct morphology when grown in Stuttgart with 3L, 7S and 9S being confirmed by meiotic analysis to date. The plants for 4L are trisomic but the morphology does not match the IRRI description. Meiotic analyses of the panicles collected this summer should be completed during the current year. In questionable cases like the 4L telotrisomic line, the trisomic chromosome will be verified with chromosome arm specific BAC clones using in situ hybridization procedures. When this project is complete, all twelve primary trisomic lines and 2) a secondary trisomic and/or telosomic line for at least one chromosome arm representing each of the twelve rice chromosomes should be available for distribution.