Variation in leaf anatomical characteristics in chromosomal segment substitution lines of KDML105 carrying drought tolerant QTL segments

Abstract

We examined quantitative traits in leaf anatomical characteristics in 20 chromosomal segment substitution lines (CSSLs) of rice cultivar Khao Dawk Mali 105 (KDML105) carrying drought-tolerant quantitative trait loci (DT-QTL) segments from drought-tolerant donors. Two DT-QTL donor lines DH103 and DH212, drought-sensitive recurrent parent KDML105, and two drought-tolerant standard checks CT9993 and IR62266 (parental lines of DH103 and DH212) were also included for comparison. A total of 20 quantitative leaf anatomical characters were evaluated from fully expanded leaves of greenhouse-grown 30-day-old plants. The results showed that the studied rice lines displayed variations in their leaf dimensions, with the four drought-tolerant lines and almost all 20 CSSLs exhibiting wider leaves, higher number of small and total vascular bundles, higher stomatal density, and shorter stomatal length than those of KDML105. Eleven out of 20 characters were selected for principal component analysis and the studied lines were categorized into 7 groups, with the drought-tolerant standard check CT9993 clearly isolated from the others due to its outstanding characters. CSSL-9, which shared major similarities of quantitative traits to CT9993, fell outside its CSSL group. The characters related to drought tolerance ability were shared between the improved CSSL lines and the drought-tolerant lines, but differed from KDML105 and included the wider leaves, the higher number of small and total vascular bundles, and denser but smaller stomata.