91勛圖

Abstract

Low-temperature stress is a serious constraint to rice production in high-latitude temperate and high-altitude tropical regions. Rice (Oryza sativa L.), which originates from tropical or subtropical regions, is sensitive to cold stress. Cold stress at the seedling stage is a major threat to rice crop establishment and subsequent productivity. Cold tolerance is controlled by complex genetic factors. We used an F7 recombinant inbred line (RIL) population of 123 individuals derived from a cross between the coldtolerant japonica cultivar Jinbu and the cold-susceptible indica cultivar BR29 for QTL mapping. All lines classed as cold tolerant were found to contain qSCT1 and qSCT11, and in lines with only these two QTLs the R2 value was 27.1%, while the presence of additional seedling cold tolerance QTLs increased the R2 value. These two critical QTLs (qSCT1 and qSCT11) on chromosomes 1 and 11 respectively were fine mapped. To improve the seedling cold tolerance of the indica cultivar BR29, Jinbu was backcrossed with BR29 using MAS. Two advanced backcross populations (BC2F4 and BC3F3) were developed and used to confirm these QTL effects against cold stress, individually and in combination (qSCT1, qSCT11 and qSCT1+qSCT11). With 18 days of cold treatment, the average cold damage scores of lines with either or both QTLs had moderate tolerance (5.63-6.83) based on the SES (standard evaluation system for seedling cold) and the lines without the SCT QTLs demonstrated a susceptible reaction to cold stress similar to BR29. With additional cold exposure, there was greater damage to the seedlings and lines with qSCT1 became susceptible after 21 days.

Biography

S M Kim completed his PhD from Kyungpook National University and Post-doctoral studies from National Academy of Agricultural Science in RDA. He has publications in some of the reputed journals.

Email: s.kim@irri.org