MUTATION BREEDING OF A RICE DWARF LINE WITH SLIGHT YIELD LOSS UNDER DROUGHT STRESS

Asadollah Ahmadikhah

a_ahmadikhah@sbu.ac.ir
Department of Biotechnology, Faculty of New Technologies, Shahid Beheshti University, Tehran, Ian; (Iran, Islamic Republic of)

Amir Marufinia

Department of Plant Breeding and Biotechnology, Gorgan University of Agricultural Sciences and Natural Resources (Iran, Islamic Republic of)

Esmaeil Sharifzadeh

Department of Agronomy and Plant Breeding, University of Zanjan, Iran (Iran, Islamic Republic of)

Abstract

Lack of adequate water leading to drought stress is a common constraint in upland cultivation system of
rice. a rice mutant line (MT58) was developed in previous research after mutagenesis of cv. Neda by ethyl
methane sulfonate (EMS) and selected for dwarfism (18 cm shorter than Neda). The extent of its molecular
changes relative to parental cultivar was assessed by SSR and ISSR markers, and the response of the line
along with parental cultivar and another mutant line (MTA) to mild and severe water deficit, was evaluated in
a field experiment. a molecular assessment by using 41 SSR markers showed that stunt line MT58 had significant
molecular difference with two other lines as confirmed by cluster analysis. ISSR assay also proved the
considerable mutational effect of EMS on two mutant lines compared to original wild line. Field experiments
revealed that limited irrigation caused mild to severe decrease in all the studied traits including chlorophyll
contents. In both mild and sever water stress (S1 and S2) dwarf mutant MT58 had not significant differences
in plant yield from parental cultivar Neda. In mild water stress cultivar Neda and mutant line MT58, respectively,
showed highest (14%) and lowest (3%) yield loss, while in sever water stress mutant lines MTA and
MT58, respectively, showed highest (33%) and lowest (19%) yield loss. In severe stress, cultivar Neda had
highest plant height, tiller number and plant yield, and mutant MT58 had highest panicle length, total kernels
per panicle, fertile kernels and chlorophyll contents. Reduction in chlorophyll content at drought stress condition
was correlated with yield loss (0.64 and 0.697 for chl.a and chl.b, respectively). The results of this research
obviously confirm that mutant line MT58 despite of its stunt figure did not show yield difference from
its parental cultivar in drought stress.

Keywords:

drought,, morpho-physiological,, mutant,, rice,, yield loss