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Genetic Assessment of Maize (Zea mays L.) Populations Selected for Drought Tolerance.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Genetic Assessment of Maize (Zea mays L.) Populations Selected for Drought Tolerance./
Author:	Musimwa, Tatenda Rambi.
Description:	1 online resource (143 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 83-12, Section: B.
Contained By:	Dissertations Abstracts International83-12B.
Subject:	Agronomy. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28768193click for full text (PQDT)
ISBN:	9798819395196

Genetic Assessment of Maize (Zea mays L.) Populations Selected for Drought Tolerance.
Musimwa, Tatenda Rambi.

Genetic Assessment of Maize (Zea mays L.) Populations Selected for Drought Tolerance. - 1 online resource (143 pages)

Source: Dissertations Abstracts International, Volume: 83-12, Section: B.

Thesis (Ph.D.)--Iowa State University, 2022.

Includes bibliographical references

Drought is a major limiting factor for maize production in both semi-tropical and temperate regions of the world. The frequency and duration of droughts have increased because of climate change. Several methods have been employed in developing maize populations that are tolerant to drought. Recurrent selection involves the implementation of breeding methods in a cyclical and repetitive manner with the intent of improving quantitative traits. Population improvement through recurrent selection is achieved by gradually increasing the frequency of favorable alleles from one cycle to the next. The International Maize and Wheat Improvement Center (CIMMYT) developed the Drought Tolerant Population (DTP) and La Posta Sequia (LPS) semi-tropical maize populations as germplasm sources for drought tolerance breeding. This study utilized inbred lines developed from cycles 0, 3, 5 and 7 of the LPS and 0, 3, 5, 7 and 9 of the DTP population to; (i) to assess the genetic gain for grain yield in LPS and DTP populations through hybrid performance, (ii) evaluate changes in population structure, allele frequency, and population divergence/convergence within and across populations, and (iii) identify regions that have undergone selective sweeps in the two populations. Inbred lines were mated to the tester CML550 and topcrosses were evaluated across 4 sites in Mexico between 2018 and 2021. All 351 inbreds were genotyped using DArTseq markers for genomic analyses. Genetic gain for grain yield under both water-deficit and well-watered conditions was confirmed. The DTP and LPS populations had genetic gain values of 0.07 and 0.16 t ha-1 cycle-1 respectively under drought stress. Genetic gain was 0.10 and 0.17 t ha-1 cycle-1 in the DTP and LPS, respectively in the well-watered treatment. Diversity analyses showed distinctness of the two populations, and individuals from the same cycles within populations were grouped in the same clusters. Selection for drought stress tolerance resulted in population divergence of the DTP and LPS. Selective sweeps were found in several genome regions of the LPS and DTP populations. Several protein coding genes were identified in the selective sweep regions.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798819395196Subjects--Topical Terms:

2122783
Agronomy.
Subjects--Index Terms:

DroughtIndex Terms--Genre/Form:

542853
Electronic books.

Genetic Assessment of Maize (Zea mays L.) Populations Selected for Drought Tolerance.
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520 $a Drought is a major limiting factor for maize production in both semi-tropical and temperate regions of the world. The frequency and duration of droughts have increased because of climate change. Several methods have been employed in developing maize populations that are tolerant to drought. Recurrent selection involves the implementation of breeding methods in a cyclical and repetitive manner with the intent of improving quantitative traits. Population improvement through recurrent selection is achieved by gradually increasing the frequency of favorable alleles from one cycle to the next. The International Maize and Wheat Improvement Center (CIMMYT) developed the Drought Tolerant Population (DTP) and La Posta Sequia (LPS) semi-tropical maize populations as germplasm sources for drought tolerance breeding. This study utilized inbred lines developed from cycles 0, 3, 5 and 7 of the LPS and 0, 3, 5, 7 and 9 of the DTP population to; (i) to assess the genetic gain for grain yield in LPS and DTP populations through hybrid performance, (ii) evaluate changes in population structure, allele frequency, and population divergence/convergence within and across populations, and (iii) identify regions that have undergone selective sweeps in the two populations. Inbred lines were mated to the tester CML550 and topcrosses were evaluated across 4 sites in Mexico between 2018 and 2021. All 351 inbreds were genotyped using DArTseq markers for genomic analyses. Genetic gain for grain yield under both water-deficit and well-watered conditions was confirmed. The DTP and LPS populations had genetic gain values of 0.07 and 0.16 t ha-1 cycle-1 respectively under drought stress. Genetic gain was 0.10 and 0.17 t ha-1 cycle-1 in the DTP and LPS, respectively in the well-watered treatment. Diversity analyses showed distinctness of the two populations, and individuals from the same cycles within populations were grouped in the same clusters. Selection for drought stress tolerance resulted in population divergence of the DTP and LPS. Selective sweeps were found in several genome regions of the LPS and DTP populations. Several protein coding genes were identified in the selective sweep regions.
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