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Yu L.-X.,Plant and Germplasm Introduction and Testing Research | Setter T.L.,Cornell University
Environmental and Experimental Botany | Year: 2016

Maize kernel development is particularly sensitive to water stress at the early post-pollination phase. Endosperm plays an essential role in support of embryo development and represents the bulk of carbohydrate storage in the kernel. In the present study, we compared transcriptomes of developing maize endosperms between an ABA-insensitive mutant, viviparous1 (vp1), and wild type (wt) under water deficit. A total of 122 and 164 transcripts were significantly affected by water deficit in vp1 and wt, respectively. Transcript profiles indicated that the Vp1 transcription factor contributed to regulation in response to water stress at early stages of maize endosperm development. Genes involved in transcriptional regulation and signal transduction were particularly dependent on presence of a functional Vp1 allele, as 83% the stress-affected genes in these categories were up-regulated by water stress in the wt, but only 34% were up-regulated in the mutant. This suggests that the loss of ABA sensitivity altered signaling networks in response to water deficit such that the mutant was unable to up-regulate the expression of many genes that normally play regulatory roles. Thus, the Vp1 gene plays a role in regulating transcript expression in maize endosperm development in response to water deficit, and this regulation is likely modulated via ABA signaling pathway. © 2015 Published by Elsevier B.V.

Zhang T.,Plant and Germplasm Introduction and Testing Research | Yu L.-X.,Plant and Germplasm Introduction and Testing Research | Zheng P.,Washington State University | Li Y.,National Center for Genetic Resource Preservation | And 3 more authors.
PLoS ONE | Year: 2015

Drought resistance is an important breeding target for enhancing alfalfa productivity in arid and semi-Arid regions. Identification of genes involved in drought tolerance will facilitate breeding for improving drought resistance and water use efficiency in alfalfa. Our objective was to use a diversity panel of alfalfa accessions comprised of 198 cultivars and landraces to identify genes involved in drought tolerance. The panel was selected from the USDAARS National Plant Germplasm System alfalfa collection and genotyped using genotyping by sequencing. A greenhouse procedure was used for phenotyping two important traits associated with drought tolerance: drought resistance index (DRI) and relative leaf water content (RWC). Marker-trait association identified nineteen and fifteen loci associated with DRI and RWC, respectively. Alignments of target sequences flanking to the resistance loci against the reference genome of M. truncatula revealed multiple chromosomal locations. Markers associated with DRI are located on all chromosomes while markers associated with RWC are located on chromosomes 1, 2, 3, 4, 5, 6 and 7. Co-localizations of significant markers between DRI and RWC were found on chromosomes 3, 5 and 7. Most loci associated with DRI in this work overlap with the reported QTLs associated with biomass under drought in alfalfa. Additional significant markers were targeted to several contigs with unknown chromosomal locations. BLAST search using their flanking sequences revealed homology to several annotated genes with functions in stress tolerance. With further validation, these markers may be used for marker-Assisted breeding new alfalfa varieties with drought resistance and enhanced water use efficiency.Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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