Genome Wide Association of Heat Tolerance Loci of Wheat in Hotspots : Current School News

Genome Wide Association of Heat Tolerance Loci of Wheat in Hotspots of Sudan and Syria

Filed in Crop Science Project Topics, Current Projects by on September 14, 2020

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Genome Wide Association of Heat Tolerance Loci of Wheat in Hotspots of Sudan and Syria.

ABSTRACT

One hundred and eighty-nine (189) wheat genotypes were evaluated in multi-environments (Tel-hadya (Syria), Dongola (Sudan) and  Wadmedani (Sudan)) for heat tolerance  from 2011  to 2012. Genomic mapping of the quantitative trait loci underlying heat tolerance in the crop was also performed.

The field experiment was laid out in an alpha lattice design. The data obtained were subjected to restricted maximum likelihood (REML) for generation  of  best linear unbiased estimates (BLUEs).

The heat tolerance study in the two  seasons (early and  late) in Tel-hadya, Syria showed that days to heading, days to maturity and grain filling duration, plant height and grain yield were significantly (p <0.05)  reduced  in  late  season when compared with their performance in the early season.

The grain loss due to  heat  stress  in the late season compared to the early season was in the range of 58 to  88%.The effect  of heat stress on days to heading, days to maturity and grain filling duration, plant height  and grain yield of the crop varied across the sites (Late season in Tel-hadya, Dongola and Wadmedani).

The decreased effect of heat stress was most pronounced in late season in Tel- hadya than in the two sites in Sudan. The Additive  Main  effects  and  Multiplicative Interaction (AMMI) estimates showed 20 top yielding genotypes in all the sites with a grain yield range of 2.593 t/ha in Gen135 to 2.893t/ha in Gen117.

In terms of their AMMI stability values ranking, Gen 60, Gen 68, Gen101, Gen155 and Gen118 were  ranked  first,  second, third, fourth and fifth, respectively. The broad sense heritability estimates for  grain  yield ranged from 0.297 (Dongola) to 0.449 (Late season in Tel-hadya).

Other  traits  like  grain filling duration, plant height and one thousand kernel weight showed moderate to low broad sense heritability across the sites.

The path coefficient analyses across the three sites showed that days to heading,  canopy temperature and  grain filling duration had reduced direct effect  on the grain yield, while biomass and harvest index showed positive direct effect on the grain yield.

Days to maturity showed negative direct influence on the grain  yield in the  late season  in Tel-hadya, but positive direct effect was observed in the two environments in Sudan.

The broad sense heritability of days to heading ranged from 0.804 (Wadmedani) to 0.908 (Late season in Tel-hadya), while days to maturity ranged from 0.68 (Dongola) to  0.793  (Late season in Tel-hadya).

The structure analysis revealed that the wheat germplasm studied had seven sub-populations. The linkage disequilibrium (LD) analysis obtained  showed  that  the  LD decay was approximately at 25cM.

The genome wide association mapping of the quantitative trait loci associated with heat tolerance showed that  few  markers  were consistently detected in the three environments, while many were environment- specific.

TABLE OF CONTENTS

CERTIFICATION………… i
DEDICATION…… ii
ACKNOWLEDGEMENT… iii
TABLE OF CONTENTS…… iv
LIST OF TABLES……… v
LIST OF FIGURES…… vii
APPENDICES…… viii
ABSTRACT… ix
INTRODUCTION………… 1
LITERATURE REVIEW……… 4
Botany and Adaptation of Wheat….. 4
Genome of Wheat ….. 5
Importance of Wheat ……. 5
Effects of Heat stress on Wheat Crop……. 6
Bases for Screening Wheat for Heat Tolerance…. 7
Molecular Markers………… 11
Genetic Mapping Approaches.. 15
MATERIALS AND METHODS… 19
RESULTS… 25
DISCUSSION…… 100
CONCLUSION…… 111
REFERENCES……… 113
APPENDICES… 128

INTRODUCTION

Bread wheat (Triticum aestivum L.) is unarguably one of the world’s most important and widely consumed cereal crop (Asif et al., 2005; Bushuk, 1998). The flour is used for making bread, biscuits, confectionary products, noodles,  wheat  gluten  among  others.

The world population is expected to reach about 9 billion by the end of the 21st century, and it has been predicted that the demand for cereals, especially wheat, will increase by approximately 50% by 2030 (Borlaug and Dowswell, 2003).

Wheat production attracts increasing attention globally owing to its importance as a staple food crop, such that the availability of wheat and wheat products are seen as a food security issue in many countries. This has led to growing of wheat in many parts of the world even where it was not formerly grown.

Paliwal et al. (2012) indicated that wheat is one of the most broadly adapted cereals. Although wheat is a thermo sensitive long day crop that requires  relatively low temperature for its optimal yield, it is being grown in the tropics and subtropics despite the relatively high temperature that is associated with the areas  (Rehman et al., 2009).

In spite of the growing attention on the crop globally, Ali (2011) reported that its production in many regions of the world is below average because of adverse environmental conditions.

High temperature which imposes heat  stress on wheat is a major limitation to its productivity in arid, semi- arid, tropical  and  subtropical  regions of the world (Ashraf and Harris, 2005).

REFERENCES

Akbari M.,Wenzl, P., Caig, V., Carling, J; Xia, L., and Yang, S. (2006). Diversity arrays technology (DArT) for high-throughput profiling of the hexaploid wheat genome. Theoretical and Applied Genetics 113,1409-1420.

Ali, M.A. (2011). Response to pedigree selection for earliness and grain yield in spring wheat under heat stress. Asian Journal of Crop Science 3,118-129.

Al-Khatib, K and Paulsen, G.M. (1984). Mode of high temperature injury to wheat  during  grain development. Plant Physiol., 61: 363-368.

Al-Khatib, K and Paulsen, G. M (1990). Photosynthesis and productivity during high temperature stress of wheat genotypes from major world regions. Crop Science 30:1127-1132.

Almeselmani, M., Deshmukh, P.S., Sairam, R. K (2006). Protective role of  antioxidant enzymes under high temperature stress. Plant science 171, 382-388

Al- Otayk, S. M (2010). Performance of Yield and Stability of Wheat Genotypes under High Stress Environments of the Central Region of Saudi Arabia.  JKAU: Met.,  Env.  &  Arid Land Agric. Sci., Vol. 21, No.1, pp: 81-92

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