SCREENING OF SELECTED WHEAT (Triticum aestivum L) LINES FOR ALUMINIUM TOXICITY TOLERANCE USING PHENOTYPIC AND SSR MARKERS

Abstract

This study was conducted to determine the Aluminium tolerance of fifteen genotypes of wheat. Aluminium (Al) toxicity is one of the major limiting factors for wheat production. Al toxicity inhibits root cell division and elongation, thus reducing water and nutrient uptake, consequently resulting in poor plant growth and yield. The study involved field evaluation with wheat genotypes and two laboratory experiments. In field evaluation, wheat was grown in three locations (Chepkoilel, Moiben and Kaptagat) arranged in Randomized Complete Block Design (RCBD) and replicated three times. Tiller numbers, spikelets number, main tiller height, main head length, seed yield and 1000 kernel weight measured. The second experiment was physiological test which was carried out using Magnavaca (nutrient) solution in the laboratory to determine length of root growth. Where sufficient number of wheat seeds was set to germinate on trays between germination papers moistened with 20 ml of 18 mΩ H20 and placed in a growth chamber set at 26 oC in darkness for four days. Seedling seminal roots were then inserted through the mesh bottoms and allowed to grow in nutrient solutions for four days then Relative Net Root Growth (RNRG) determined. Third experiment involved Deoxyribonucleic acid (DNA) extraction which was done using Dellaporta protocol, followed by DNA amplification using Simple Sequence Repeat (SSR) primers. The Polymerase Chain Reaction (PCR) products were then electrophoresed on 3% agarose gel containing 7 μL ethidium bromide (EtBr), at 100 V for 1 hour, and then observed under a UV transilluminator and analysis was done using simple matching (UPGMA) software, photographed using gel documentation unit. Bands were then scored, where (1) indicate presence, (0) indicate absence. The data was then analyzed using SAS and means separated using LSD. Field screening showed that high yielding lines were ELD/AS/14/L6 and ELD/AS/14/L13 while low performing varieties were, Robin and Njoro(BW)11.When subjected to two Aluminium (Magnavaca test) level of 148 µM and 222 µM, five lines; ELD/AS/14/L1, ELD/AS/14/L4, ELD/AS/14/L6, ELD/AS/14/L8, ELD/AS/14/L3, and two varieties; Robin and Njoro (BW)11 were found to have aluminium tolerance. Significant variation in yield and yield related components were either due to environmental influence and interaction between environment and genotypes. These genotypes were clustered into nine groups by their decent when molecular analysis was done, these are: (1) ELD/AS/14/L1 and ELD/AS/14/L8, (11) ELD/AS/14/L4 (111) ROBIN, NJOROBW11 (IV) ELD/AS/14/L2, ELD/AS/14/L5 (V) ELD/AS/14/L9 (VI) ELD/AS/14/L3, ELD/AS/14/L7 (V11) ELD/AS/14/L10, ELD/AS/14/L11 (VIII) ELD/AS/14/L6, ELD/AS/14/L13 and (1X) ELD/AS/14/L12. The highest yields across the three sites were recorded in lines ELD/AS/14/L6, ELD/AS/14/L13, ELD/AS/14/L2, ELD/AS/14/L9 and ELD/AS/14/L10. Lines ELD/AS/14/L1, ELD/AS/14/L4, ELD/AS/14/L6, ELD/AS/14/L8, ELD/AS/14/L13, Robin and Njoro BW11 were tolerant to aluminium phytotoxicity and they should be considered in breeding for tolerance to Al-toxicity. The dendrogram showed that lines ELD/AS/14/L6 and ELD/AS/14/L13 had closer genetic relationship.