Genetic and physiological responses of selected Indonesian rice (Oryza sativa Linn.) genotypes to aluminum toxicity and phosphorus deficiency experienced in acid soil condition

Date

12-2014

Abstract

Acid soils are widely distributed in tropical and subtropical regions, and crop production in these areas is severely reduced due to several abiotic factors including aluminum (Al) toxicity and phosphorus (P) deficiency. Several physiological and genetic studies were conducted to assess the responses of a set of Indonesian rice genotype to Al toxicity and P deficiency, the two major constraints for crop production in acid upland soils of Indonesia. This is to help develop rice cultivars with dual tolerance of these two stresses.

The study consists of three main components. Physiological studies ranked Dupa as one of the most Al-tolerant genotype among the Indonesian local and international varieties evaluated. Dupa produced less MDA under Al toxicity, indicating less membrane damage in root tissues. It also showed less Al uptake and accumulated higher Ca+2, P, Mg+2 and Zn. Together these factors resulted in better root and shoot growth.

The second study was conducted to assess the genetic factors controlling aluminum tolerance in the Indonesian rice variety, ‘Dupa’. Three QTLs associated with Al tolerance, Altr1-a, Altr1-b, and Altr3 were detected with LOD values of 3.5, 2.7, and 2.99, respectively. These three OTLs explained 48.5% of the total phenotypic variance in the population. Twenty-seven genes associated with aluminum tolerance were found to co-localize within these QTL regions. Moreover, Dupa, a tropical japonica genotype, had less non-synonymous mutated SNPs than the Indica genotypes, Some of these genes were expressed differently under Al stress and warrant further investigations for functional analyses and use in breeding.

The third study evaluated tolerance to Phosphorus deficiency in a set of Indonesian lines introgressed With Pup1, a major QTL associate with P uptake from P-deficient soils. A series of evaluation studies were conducted, but did not clearly identify the best Pup1 line for introgression of Al toxicity QTLs for dual tolerance. Pup1 insertion was fixed in BC2F3 in Indonesian NILs. However, the beneficial effect was not clearly detected in the field during vegetative and reproductive stages in BC2F6 generation. Background genotyping showed that larger segments exceeded the size of Pupl locus were inserted. Besides, several additional insertions were also detected on other chromosomes, aside from Pupl. Several factors might have contributed to the poor performance of the Indonesian NILS, including their poor adaptation to lowland conditions of the trials conducted at IRRI and the possible side effects of the additional segments dragged from the donor parents.

Document Type

Dissertation

Degree

Doctor of Philosophy in Genetics

College

Graduate School (GS)

Adviser/Committee Chair

Ma. Genaleen Q. Diaz

Co-adviser

Abdelbagi M. Ismail

Committee Member

Maribel L. Dionisio-Sese, Merlyn S. Mendioro, Sigrid Heuer

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 996 2014 G2 N87

This document is currently not available here.

Share

COinS