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. 2015 Dec 29;10(12):e0145970.
doi: 10.1371/journal.pone.0145970. eCollection 2015.

Copy Number Variation of Cytokinin Oxidase Gene Tackx4 Associated with Grain Weight and Chlorophyll Content of Flag Leaf in Common Wheat

Cheng Chang  1 , Jie Lu  1 , Hai-Ping Zhang  1 , Chuan-Xi Ma  1 , Genlou Sun  1   2
Affiliations

Copy Number Variation of Cytokinin Oxidase Gene Tackx4 Associated with Grain Weight and Chlorophyll Content of Flag Leaf in Common Wheat

Cheng Chang et al. PLoS One. .

Abstract

As the main pigment in photosynthesis, chlorophyll significantly affects grain filling and grain weight of crop. Cytokinin (CTK) can effectively increase chlorophyll content and chloroplast stability, but it is irreversibly inactivated by cytokinin oxidase (CKX). In this study, therefore, twenty-four pairs of primers were designed to identify variations of wheat CKX (Tackx) genes associated with flag leaf chlorophyll content after anthesis, as well as grain weight in 169 recombinant inbred lines (RIL) derived from Triticum aestivum Jing 411 × Hongmangchun 21. Results indicated variation of Tackx4, identified by primer pair T19-20, was proven to significantly associate with chlorophyll content and grain weight in the RIL population. Here, two Tackx4 patterns were identified: one with two co-segregated fragments (Tackx4-1/Tackx4-2) containing 618 bp and 620 bp in size (as in Jing 411), and another with no PCR product. The two genotypes were designated as genotype-A and genotype-B, respectively. Grain weight and leaf chlorophyll content at 5~15 days after anthesis (DAA) were significantly higher in genotype-A lines than those in genotype-B lines. Mapping analysis indicated Tackx4 was closely linked to Xwmc169 on chromosome 3AL, as well as co-segregated with a major quantitative trait locus (QTL) for both grain weight and chlorophyll content of flag leaf at 5~15 DAA. This QTL explained 8.9~22.3% phenotypic variations of the two traits across four cropping seasons. Among 102 wheat varieties, a third genotype of Tackx4 was found and designated as genotype-C, also having two co-segregated fragments, Tackx4-2 and Tackx4-3 (615bp). The sequences of three fragments, Tackx4-1, Tackx4-2, and Tackx4-3, showed high identity (>98%). Therefore, these fragments could be considered as different copies at Tackx4 locus on chromosome 3AL. The effect of copy number variation (CNV) of Tackx4 was further validated. In general, genotype-A contains both significantly higher grain weight and flag leaf chlorophyll content at 5~15 DAA than those in genotype-B and genotype-C, among 102 varieties under various environments.

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Conflict of interest statement

Competing Interests: This manuscript or substantial parts of it, submitted to the journal has not be under consideration by any other journal. No material submitted as part of a manuscript infringes existing copyrights, or the rights of a third party. All authors have approved the manuscript. The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Allelic variation of Tackx4 in the RILs population derived from Jing 411 × Hongmangchun 21.
Lanes 1–17: 1, Jing 411; 2, Hongmangchun 21; 3, JH2; 4, JH17; 5, JH3; 6, JH11; 7, JH7; 8, JH15; 9, JH12; 10, JH13; 11, JH14; 12, JH20; 13, JH21; 14, JH19; 15, JH25; 16, JH26; 17, JH27. The genotype of Jing 411 (genotype-A) and Hongmangchun 21 (genotype-B) was marked “A” and “B” genotype, respectively. JH2, JH13, JH11, JH12, etc., represented individual names of the RILs.
Fig 2
Fig 2. Amplified patterns of Tackx4 from Chinese Spring nullisomic—tetrasomics using T19-20 primer pair.
Lanes 1–14: 1, Jing411; 2, Yumai 8679; 3, Yongchuanbaikemai (Chinese landrace); 4, Chinese spring; 5, Yongchuanbaimaizi (Chinese landrace); 6, Wanxianbaizi (Chinese landrace); 7, Heshangmai; 8, N3BT3A; 9, N3DT3A; 10, N3BT3D; 11, N3AT3D; 12, N3AT3B; 13,Yangmai 158; 14, Y6 (Aegilops tauschii, DD). The genotype-A (Tackx4-1 and Tackx4-2) and genotype-C (Tackx4-2 and Tackx4-3) are marked with A and C, respectively.
Fig 3
Fig 3. Linkage map of Tackx4 on chromosome 3A of wheat.
The four shaded boxes represented the four traits (C5, C10, C15 and TGW, respectively).
Fig 4
Fig 4. Amplification patterns of Tackx4 gene for 12 of the 102 wheat varieties using T19-20 primer pair.
Lanes 1–12: 1, Jing411; 2, Yumai 8679; 3, Jimai 20; 4, Zhongmai 9; 5, Zheng 9023; 6, Hongmangchun 21; 7, Wanxianbaimaizi; 8, Wangshuibai; 9, Shan 225; 10, Shan 160; 11, Yumai 8679; 12, Xiaobingmai 33.
Fig 5
Fig 5. Sequence alignment of Tackx4-1, Tackx4-2, Tackx4-3, and Tackx4b (BM138354).
Primer pair sequences and intron regions were marked. The primer pair was marked with arrows and the intron sequence was boxed.
Fig 6
Fig 6. Homology analysis of Tackx4 from wheat (Tackx4-1, Tackx4-2 and Tackx4-3), Hvckx4a from barley, and Osckx4 from rice.
The percentages indicated the sequence identity among them.
See this image and copyright information in PMC

References

    1. Evans LT (1993) Crop evolution, adaption and yield New York: Cambridge.
    1. Austin RB, Edrich JA, Ford MA, Blackwell RD (1977) The fate of the dry matter, carbohydrates and C lost from the leaves and stems of wheat during grain filling. Ann Bot 41: 1309–1321.
    1. Bidinger F, Musgrave RB, Fisher RA (1977) Contribution of stored pre-anthesis assimilate to grain yield in wheat and barley. Nature 270: 431–433.
    1. Araus JI, Bort J, CecCadelli S and Grando S (1997) Relationship between leaf structure and carbon isotope discrimination in field grown barley. Plant Physiol Biochem 35: 533–541.
    1. Thomas JA, Jeffrey AC, Atsuko K and David MK (2005) Regulating the proton budget of higher plant photosynthesis. Proc Natl Acad Sci 102: 9709–9713. - PMC - PubMed

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