Comparison of Methods of Pollen Selection for Heat Tolerance and Their Effect in Segregating Population of Maize ( Zea m
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FULL-LENGTH RESEARCH ARTICLE
Comparison of Methods of Pollen Selection for Heat Tolerance and Their Effect in Segregating Population of Maize (Zea mays) Ashutosh Singh1,2 • R. L. Ravikumar2 • Suresh H. Antre2
Received: 18 March 2019 / Accepted: 31 August 2020 Ó NAAS (National Academy of Agricultural Sciences) 2020
Abstract The reproductive stage in many crops including Maize (Zea mays L.) is most sensitive to heat stress. Due to limitations in sporophytic selection, an alternative pollen selection approach opens a way for breeders to develop heat stress resilient lines. In present study, the efficiency of different methods of pollen selection for heat stress tolerance was evaluated. The effect of selection in F1 generation in terms of the frequency of heat-tolerant plants in F2 generation was assessed. The heat susceptible line BTM4 was crossed to heat-tolerant BTM6, and the true F1 plants were identified using two SSR markers. Three different methods of pollen selection for heat tolerance, viz. incubating the freshly dehisced pollen grains of F1 plants at 36 °C for 3 h in growth chamber (GRC), dry bath (DB) before selfing and growing F1 plants in summer at ARS, Bheemarayanagudi (BGD). Thus, selected F2 from different treatments was produced. The control F2 was also produced without heat treatment of pollen grains. The control and selected F2 population were compared for heat tolerance by selfing the F2 plants with heat-stressed pollen grains. The selected F2 (GRC) showed superiority over other methods for seed yield traits and its component traits and also positive effect of pollen selection for heat tolerance. Keywords Generation Susceptible Treatment Tolerant Selection Pollen grains
Introduction Climate change impacts cereal production mainly through heat and water stress [22]. The productivity of wheat, maize and rice is predicted to decrease in both tropical and temperate regions [2]. The model shows that 1 °C increase in global mean temperature declines the grain yields by 7.4% in maize which is highest reduction among cereals [33]. Among the developmental stages, the reproductive stage is the most sensitive to heat stress which leads to delay in
& Ashutosh Singh [email protected] 1
Hi-tech Laboratory of Sugarcane Research Institute of Dr, Rajendra Prasad Central Agricultural University, Pusa Samastipur, Bihar 848125, India
2
Department of Plant Biotechnology UAS GKVK, Bangalore, Karnataka 560065, India
the flowering, increase in days to anthesis and silking interval (ASI) [16] and increase pollen sterility in maize [30]. Though a wide range of screenable traits are reported which allow successful selection for heat tolerance in different crops in distinct field conditions [10, 23], the methods are not very effective for screening as heat stress is a complex quantitative trait. The lack of comprehensive screening method for heat tolerance at sporophytic level is the major challenge in identification and development of heat stress-tolerant lines. The pollen has been frequently used
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